@article{nuruzzaman_colella_uzoewulu_meo_gross_ishizawa_sana_zhang_hoff_medlock_et al._2024, title={Hexafluoroisopropanol as a Bioconjugation Medium of Ultrafast, Tryptophan-Selective Catalysis}, volume={2}, ISSN={["1520-5126"]}, DOI={10.1021/jacs.3c13447}, abstractNote={The past decade has seen a remarkable growth in the number of bioconjugation techniques in chemistry, biology, material science, and biomedical fields. A core design element in bioconjugation technology is a chemical reaction that can form a covalent bond between the protein of interest and the labeling reagent. Achieving chemoselective protein bioconjugation in aqueous media is challenging, especially for generally less reactive amino acid residues, such as tryptophan. We present here the development of tryptophan-selective bioconjugation methods through ultrafast Lewis acid-catalyzed reactions in hexafluoroisopropanol (HFIP). Structure-reactivity relationship studies have revealed a combination of thiophene and ethanol moieties to give a suitable labeling reagent for this bioconjugation process, which enables modification of peptides and proteins in an extremely rapid reaction unencumbered by noticeable side reactions. The capability of the labeling method also facilitated radiofluorination application as well as antibody functionalization. Enhancement of an α-helix by HFIP leads to its compatibility with a certain protein, and this report also demonstrates a further stabilization strategy achieved by the addition of an ionic liquid to the HFIP medium. The nonaqueous bioconjugation approaches allow access to numerous chemical reactions that are unavailable in traditional aqueous processes and will further advance the chemistry of proteins.}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Nuruzzaman, Mohammad and Colella, Brandon M. and Uzoewulu, Chiamaka P. and Meo, Alissa E. and Gross, Elizabeth J. and Ishizawa, Seiya and Sana, Sravani and Zhang, He and Hoff, Meredith E. and Medlock, Bryce T. W. and et al.}, year={2024}, month={Feb} }
 @article{gouveia_ison_2022, title={Well-Defined ENENES Re and Mn Complexes and Their Application in Catalysis: The Role of Potassium tert-Butoxide}, volume={41}, ISSN={["1520-6041"]}, DOI={10.1021/acs.organomet.2c00261}, abstractNote={A new family of air-stable Re and Mn complexes bearing bidentate NNS (ENENES) ligands with the general formula E(CH2)2NH(CH)2SR (E = −NC4H8O or −NC5H10, R = Ph or thiophenyl) is introduced. All Re and Mn complexes were catalysts for the hydrogenation of aldehydes. The Mn catalysts were active at milder conditions. A rhenium–hydride complex, featuring cis Re–H and N–H moieties, was isolated to provide an insight into the mechanism for this reaction. DFT (B3PW91-D3) and experimental data suggest that there are two pathways for this system, with and without the presence of the base (t-BuOK). The pathway that included t-BuOK was lower in energy, providing a greater driving force for the overall reaction.}, number={19}, journal={ORGANOMETALLICS}, author={Gouveia, Liana Ribeiro and Ison, Elon A.}, year={2022}, month={Oct}, pages={2678–2687} }
 @article{marshburn_ashley_curtin_sultana_liu_vinueza_ison_jakubikova_2021, title={Are all charge-transfer parameters created equally? A study of functional dependence and excited-state charge-transfer quantification across two dye families}, volume={8}, ISSN={["1463-9084"]}, url={https://doi.org/10.1039/D1CP03383B}, DOI={10.1039/d1cp03383b}, abstractNote={Twenty dyes from the Max Weaver Dye Library were used to benchmark six commonly used DFT functionals to understand the interplay between the errors in the calculated excitation energies and the degree of charge transfer character of the excitations.}, journal={PHYSICAL CHEMISTRY CHEMICAL PHYSICS}, publisher={Royal Society of Chemistry (RSC)}, author={Marshburn, Richard Drew and Ashley, Daniel C. and Curtin, Gregory M. and Sultana, Nadia and Liu, Chang and Vinueza, Nelson R. and Ison, Elon A. and Jakubikova, Elena}, year={2021}, month={Aug} }
 @article{ison_tubb_2021, title={Energy Decomposition Analysis of Lewis Acid/Base Adducts and Frustrated Lewis Pairs: The Use of E-Orb/E-Steric Ratios as a Reaction Parameter}, volume={60}, ISSN={["1520-510X"]}, DOI={10.1021/acs.inorgchem.1c00911}, abstractNote={The nature of bonding in classical adducts and frustrated Lewis pairs (FLPs) of oxorhenium and nitridorhenium complexes with B(C6F5)3 was investigated computationally (B3PW91-D3). These studies have revealed that the primary noncovalent interaction (NCI) in the FLPs involves lone pair/π interactions between the terminal M≡X bond and the aromatic C6F5 ring in B(C6F5)3. Energy decomposition analyses on classical adducts and FLPs reveal that these species can be defined by the ratio (EOrb/ESteric) of covalent-to-noncovalent contributions to the total interaction energy, EInt. This type of analysis reveals that values for FLPs exist in a narrow range (1.2-2.5), with values for adducts significantly outside this range. The application of this method to other main-group combinations of Lewis acids and bases that have been shown to exhibit FLP reactivity yields similar results. These data suggest that similar NCIs are present in both transition-metal and main-group FLPs, especially where Lewis acids such as B(C6F5)3 are utilized.}, number={18}, journal={INORGANIC CHEMISTRY}, author={Ison, Elon A. and Tubb, Joshua L.}, year={2021}, month={Sep}, pages={13797–13805} }
 @article{davern_lowe_rosfi_ison_proulx_2021, title={Submonomer synthesis of peptoids containing trans-inducing N-imino- and N-alkylamino-glycines}, volume={5}, ISSN={["2041-6539"]}, DOI={10.1039/d1sc00717c}, abstractNote={The use of hydrazones as a new type of submonomer in peptoid synthesis is described, giving access to peptoid monomers that are structure-inducing.}, journal={CHEMICAL SCIENCE}, author={Davern, Carolynn M. and Lowe, Brandon D. and Rosfi, Adam and Ison, Elon A. and Proulx, Caroline}, year={2021}, month={May} }
 @article{guzmán santiago_brown_sommer_ison_2020, title={Identification of key functionalization species in the Cp*Ir(iii)-catalyzed-ortho halogenation of benzamides}, volume={49}, ISSN={1477-9226 1477-9234}, url={http://dx.doi.org/10.1039/D0DT00565G}, DOI={10.1039/D0DT00565G}, abstractNote={Cp*Ir(iii) complexes have been shown to be effective for the halogenation of N,N-diisopropylbenzamides with N-halosuccinimide as a suitable halogen source.}, number={45}, journal={Dalton Transactions}, publisher={Royal Society of Chemistry (RSC)}, author={Guzmán Santiago, Alexis J. and Brown, Caleb A. and Sommer, Roger D. and Ison, Elon A.}, year={2020}, pages={16166–16174} }
 @article{brown_abrahamse_ison_2020, title={Re-Silane complexes as frustrated lewis pairs for catalytic hydrosilylation}, volume={49}, ISSN={["1477-9234"]}, DOI={10.1039/d0dt02084b}, abstractNote={A pathway for the catalytic hydrosilylation of carbonyl substrates was calculated by DFT(B3PW91-D3) for both cationic and neutral Re(iii) species. This mechanism is similar to the pathway calculated for M(C6F5)3 (M = B, Al and Ga) catalysts.}, number={32}, journal={DALTON TRANSACTIONS}, author={Brown, Caleb A. and Abrahamse, Michael and Ison, Elon A.}, year={2020}, month={Aug}, pages={11403–11411} }
 @article{brown_lilly_lambic_sommer_ison_2020, title={Synthesis and Reactivity of Re(III) and Re(V) Fischer Carbenes}, volume={39}, ISSN={["1520-6041"]}, DOI={10.1021/acs.organomet.9b00600}, abstractNote={Direct insertion of CO and isocyanides, RNC, into Re–R bonds results in high-oxidation-state acyl and iminoacyl complexes that can be treated with an electrophile to generate rare examples of rheni...}, number={3}, journal={ORGANOMETALLICS}, author={Brown, Caleb A. and Lilly, Cassandra P. and Lambic, Nikola S. and Sommer, Roger D. and Ison, Elon A.}, year={2020}, month={Feb}, pages={388–396} }
 @article{lambić_sommer_ison_2020, title={Synthesis and reactivity of nitridorhenium complexes incorporating the mercaptoethylsulfide (SSS) ligand}, volume={49}, url={https://doi.org/10.1039/D0DT00631A}, DOI={10.1039/D0DT00631A}, abstractNote={The steric profile of the SSS ligand combined with enhanced nucleophilicity of the nitrido group is important for FLP reactivity.}, journal={Dalton Transactions}, publisher={Royal Society of Chemistry (RSC)}, author={Lambić, N.S. and Sommer, R.D. and Ison, E.A.}, year={2020}, pages={6127–6134} }
 @inbook{ison_2019, place={Weinheim, Germany}, title={Toward N—N Bond Cleavage: Synthesis and Reactivity of Group 7 Dinitrogen Complexes}, ISBN={9783527344253 9783527344291 9783527344277 9783527344260}, DOI={10.1002/9783527344260.ch5}, abstractNote={By far, the most commonly encountered group 7 dinitrogen (N2) complexes involve terminal N2 ligands. The majority of these molecules incorporate rhenium, with sporadic examples of complexes with manganese and to a lesser extent technetium. Complexes incorporating cyclopentadienyl (Cp) and its derivatives were also synthesized from strong reducing agents. Terminal nitrogen complexes have been shown to react with transition metals to form bridged dinitrogen complexes. This chapter outlines two examples where a coordinated N2 ligand has been reduced. For N2 cleavage, the density functional theory (DFT) calculations suggest that the transition state for this reaction contains a zigzag structure similar to the molybdenum complex reported by Cummins and coworkers. Given that both terminal and bridged N2 complexes are known, and at least in one case, a bridged dinitrogen complex is proposed to lead to N2 cleavage, the prospect for catalytic N2 activation with group 7 is still promising.}, booktitle={Transition Metal‐Dinitrogen Complexes: Preparation and Reactivity}, publisher={Wiley}, author={Ison, E.A.}, editor={Nishibayashi, Y.Editor}, year={2019}, pages={271–284} }
 @article{lambic_sommer_ison_2018, title={High-valent nitridorhenium(V) complexes containing PNP ligands: implications of ligand flexibility}, volume={47}, ISSN={["1477-9234"]}, url={https://doi.org/10.1039/C7DT03615A}, DOI={10.1039/c7dt03615a}, abstractNote={The synthesis of (PNP)Re(N)X (PNP = [2-P(CHMe2)2-4-MeC6H3]2N, X = Cl and Me) complexes is described.}, number={3}, journal={DALTON TRANSACTIONS}, publisher={Royal Society of Chemistry (RSC)}, author={Lambic, Nikola S. and Sommer, Roger D. and Ison, Elon A.}, year={2018}, month={Jan}, pages={758–768} }
 @article{perez_smeltz_sommer_boyle_ison_2017, title={Cationic rhenium ((III)) complexes: synthesis, characterization, and reactivity for hydrosilylation of aldehydes}, volume={46}, DOI={10.1039/c7dt00271h}, abstractNote={Cationic Re(iii) complexes are shown to be more active for the catalytic hydrosilylation of benzaldehydes than their neutral acetate precursors.}, number={14}, journal={Dalton Transactions (Cambridge, England : 2003)}, author={Perez, D. E. and Smeltz, J. L. and Sommer, Roger D. and Boyle, P. D. and Ison, Elon}, year={2017}, pages={4609–4616} }
 @article{lambic_brown_sommer_ison_2017, title={Dramatic Increase in the Rate of Olefin Insertion by Coordination of Lewis Acids to the Oxo Ligand in Oxorhenium(V) Hydrides}, volume={36}, ISSN={["1520-6041"]}, DOI={10.1021/acs.organomet.7b00291}, abstractNote={In this work we show that classic coordination of the oxo group in an oxorhenium hydride complex to M(C6F5)3 (M = Al, B) leads to dramatic increases in the rate of migratory olefin insertion. Combined experimental and computational studies have been utilized to understand the reasons for the rate enhancement upon coordination of the oxo group to the Lewis acid. The mechanism for migratory insertion involves coordination of the olefin to rhenium in the equatorial plane. This induces mixing of the rhenium–hydride σ bond with a rhenium–oxygen π* orbital. This results in an accumulation of electron density on the oxo ligand. The Lewis acid lowers the barrier for migratory insertion by diminishing the electron density on the oxo ligand in the transition state.}, number={10}, journal={ORGANOMETALLICS}, publisher={American Chemical Society (ACS)}, author={Lambic, Nikola S. and Brown, Caleb A. and Sommer, Roger D. and Ison, Elon A.}, year={2017}, month={May}, pages={2042–2051} }
 @article{ison_ison_perry_2017, title={Oxorhenium Complexes for Catalytic Hydrosilylation and Hydrolytic Hydrogen Production: A Multiweek Advanced Laboratory Experiment for Undergraduate Students}, volume={94}, ISSN={0021-9584 1938-1328}, url={http://dx.doi.org/10.1021/ACS.JCHEMED.6B00954}, DOI={10.1021/ACS.JCHEMED.6B00954}, abstractNote={An effective way of teaching undergraduates a full complement of research skills is through a multiweek advanced laboratory experiment. Here we outline a comprehensive set of experiments adapted from current primary literature focusing on organic and inorganic synthesis, catalysis, reactivity, and reaction kinetics. The catalyst, bis(2-(2′-hydroxyphenyl)-2-oxazoline)oxorhenium(V) tetrapentafluorophenylborate (1) is isolated through a multistep reaction starting with the formation of the ligand, 2-(2′-hydroxyphenyl)-2-oxazoline (2), followed by complexation of a Re–oxo precursor to form chlorobis(2-(2′-hydroxyphenyl)-2-oxazoline)oxorhenium(V) (3). Both Re(V)–oxo complexes are diamagnetic and allow for NMR analysis. Complex 1 is an air-stable and highly active catalyst for two reactions: (1) hydrosilylation of carbonyls and (2) hydrolysis of Et3SiH to form Et3SiOH and H2 gas. Students monitor the evolution of hydrogen gas in the second reaction and use the data to investigate the reaction kinetics in order ...}, number={6}, journal={Journal of Chemical Education}, publisher={American Chemical Society (ACS)}, author={Ison, A. and Ison, E. A. and Perry, C. M.}, year={2017}, month={Apr}, pages={790–794} }
 @article{lambic_sommer_ison_2017, title={Tuning Catalytic Activity in the Hydrogenation of Unactivated Olefins with Transition-Metal Oxos as the Lewis Base Component of Frustrated Lewis Pairs}, volume={7}, ISSN={["2155-5435"]}, DOI={10.1021/acscatal.6b03313}, abstractNote={The steric and electronic demands of the catalytic olefin hydrogenation of tert-butylethylene with oxorhenium/Lewis acid FLPs were evaluated. The sterics of the ligand were altered by installing bulkier isopropyl groups in the 2,6-positions of the diamidopyridine (DAP) ligand. Lewis acid/base adducts were not isolated for complexes with this ligand; however, species incorporating isopropyl groups were still active in catalytic hydrogenation. Modifications were also made to the Lewis acid, and catalytic reactions were performed with Piers’ borane, HB(C6F5)2, and the aluminum analogue Al(C6F5)3. The rate of catalytic hydrogenation was shown to strongly correlate with the size of the alkyl, aryl, or hydride ligand. This was confirmed by a linear Taft plot with the steric sensitivity factor δ = −0.57, which suggests that reaction rates are faster with sterically larger X substituents. These data were used to develop a catalyst ((MesDAP)Re(O)(Ph)/HB(C6F5)2) that achieved a TON of 840 for the hydrogenation of t...}, number={2}, journal={ACS CATALYSIS}, publisher={American Chemical Society (ACS)}, author={Lambic, Nikola S. and Sommer, Roger D. and Ison, Elon A.}, year={2017}, month={Feb}, pages={1170–1180} }
 @article{robbins_lilly_sommer_ison_2016, title={Effect of the Ancillary Ligand on the Mechanism for CO Migratory Insertion in High-Valent Oxorhenium Complexes}, volume={35}, ISSN={["1520-6041"]}, DOI={10.1021/acs.organomet.6b00570}, abstractNote={Several oxorhenium complexes bearing an SSS pincer ligand were isolated and characterized, and their reactivity with carbon monoxide was explored. The corresponding oxorhenium(V) acyl derivatives were also isolated and characterized. Carbonylation reactions required high pressures (400 psi) and temperatures (50 °C). The mechanism for carbonylation was explored with DFT (M06) calculations and revealed that the most likely mechanism for carbonylation involved stepwise formation of CO adducts followed by migration of the carbonyl ligand to the alkyl/aryl groups.}, number={20}, journal={ORGANOMETALLICS}, publisher={American Chemical Society (ACS)}, author={Robbins, Leanna K. and Lilly, Cassandra P. and Sommer, Roger D. and Ison, Elon A.}, year={2016}, month={Oct}, pages={3530–3537} }
 @article{lambic_lilly_sommer_ison_2016, title={Mechanism for the Reaction of CO with Oxorhenium Hydrides: Migratory Insertion of CO into Rhenium Hydride and Formyl Bonds leads to Migration from Rhenium to the Oxo Ligand}, volume={35}, ISSN={["1520-6041"]}, DOI={10.1021/acs.organomet.6b00591}, abstractNote={Computational studies (M06) have been performed in synergy with experimental studies to show that the thermodynamics for insertion of CO into an oxorhenium–hydride bond to form a formyl ligand is favorable despite conventional wisdom to the contrary. Further, it is shown that insertion of CO into formyl ligands to form α-dicarbonyl ligands is also a viable pathway and results in hydroxy carbonyl or formate complexes, depending on the nature of the ancillary ligand.}, number={17}, journal={ORGANOMETALLICS}, publisher={American Chemical Society (ACS)}, author={Lambic, Nikola S. and Lilly, Cassandra P. and Sommer, Roger D. and Ison, Elon A.}, year={2016}, month={Sep}, pages={3060–3068} }
 @article{kerr_ahmed_gunay_venditto_zhu_ison_emmert_2016, title={Non-directed, carbonate-mediated C-H activation and aerobic C-H oxygenation with Cp*Ir catalysts}, volume={45}, ISSN={["1477-9234"]}, DOI={10.1039/c6dt00234j}, abstractNote={Carbonate additives enhance the activity of [Cp*Ir(H2O)3](OTf)2 for non-directed C–H activations and the aerobic C–H oxygenation of alkyl arenes.}, number={24}, journal={DALTON TRANSACTIONS}, author={Kerr, M. E. and Ahmed, I. and Gunay, A. and Venditto, N. J. and Zhu, F. and Ison, E. A. and Emmert, M. H.}, year={2016}, pages={9942–9947} }
 @article{frasco_mukherjee_sommer_perry_lambic_abboud_jakubikoya_ison_2016, title={Nondirected C-H Activation of Arenes with Cp*Ir(III) Acetate Complexes: An Experimental and Computational Study}, volume={35}, ISSN={["1520-6041"]}, DOI={10.1021/acs.organomet.6b00308}, abstractNote={Combined experimental and computational studies have revealed factors that influence the nondirected C–H activation in Cp*Ir complexes that contain carboxylate ligands. A two-step acetate-assisted pathway was shown to be operational where the first step involves substrate binding and the second step involves cleavage of the C–H bond of the substrate. A nonlinear Hammett plot was obtained to examine substituted arenes where a strong electronic dependence (ρ = 1.67) was observed for electron-donating groups, whereas no electronic dependence was observed for electron-withdrawing groups. Electron-donating substituents in the para position were shown to have a bigger impact on the C–H bond cleavage step, whereas electron-withdrawing substituents influenced the substrate-binding step. Although cleavage of the C–H bond was predicted to be more facile with arenes that contain substituents in the para position by DFT calculations, the cyclometalations of anisole and benzonitrile were observed experimentally. This ...}, number={15}, journal={ORGANOMETALLICS}, publisher={American Chemical Society (ACS)}, author={Frasco, Daniel A. and Mukherjee, Sriparna and Sommer, Roger D. and Perry, Cody M. and Lambic, Nikola S. and Abboud, Khalil A. and Jakubikoya, Elena and Ison, Elon A.}, year={2016}, month={Aug}, pages={2435–2445} }
 @article{frasco_mukherjee_sommer_perry_lambic_abboud_jakubikova_ison_2016, title={Nondirected C–H Activation of Arenes with Cp* Ir (III) Acetate Complexes: An Experimental and Computational Study}, volume={35}, DOI={https://doi.org/10.1021/acs.organomet.6b00308}, abstractNote={Combined experimental and computational studies have revealed factors that influence the nondirected C–H activation in Cp*Ir complexes that contain carboxylate ligands. A two-step acetate-assisted pathway was shown to be operational where the first step involves substrate binding and the second step involves cleavage of the C–H bond of the substrate. A nonlinear Hammett plot was obtained to examine substituted arenes where a strong electronic dependence (ρ = 1.67) was observed for electron-donating groups, whereas no electronic dependence was observed for electron-withdrawing groups. Electron-donating substituents in the para position were shown to have a bigger impact on the C–H bond cleavage step, whereas electron-withdrawing substituents influenced the substrate-binding step. Although cleavage of the C–H bond was predicted to be more facile with arenes that contain substituents in the para position by DFT calculations, the cyclometalations of anisole and benzonitrile were observed experimentally. This suggests that these substituents, even though they are weakly directing, still result in cyclometalation because the barriers for activation at the ortho and para positions of arenes are comparable (24.3 and 26.5 kcal/mol, respectively). Incorporation of a weakly bound ligand was found to be necessary for facile reactivity. It is predicted by DFT calculations that the replacement of an oxygen atom with a nitrogen atom in the carboxylate ligand would lead to a dramatic reduction in the barrier for C–H activation, as the incorporation of formimidate and N-methylformimidate ligands leads to barriers of 23.4 and 21.7 kcal/mol, respectively. These values are significantly lower than the barrier calculated for the analogous acetate ligand (28.2 kcal/mol).}, journal={Organometallics}, publisher={American Chemical Society}, author={Frasco, D.A. and Mukherjee, S. and Sommer, R.D. and Perry, C.M. and Lambic, N.S. and Abboud, K. A. and Jakubikova, E and Ison, E. A.}, year={2016}, month={Jul}, pages={2435–2445} }
 @article{lambic_lilly_robbins_sommer_ison_2016, title={Reductive Carbonylation of Oxorhenium Hydrides Induced by Lewis Acids}, volume={35}, ISSN={["1520-6041"]}, DOI={10.1021/acs.organomet.6b00393}, abstractNote={Several oxorhenium hydride complexes with chelating diamidopyridine (DAP), diamidoamine (DAAm), and 2-mercaptoethyl sulfide (SSS) groups have been isolated and characterized. Adduct formation is observed when the DAP complex 1a is treated with the Lewis acid B(C6F5)3. However, treatment of 1a,b with B(C6F5)3 or BF3·OEt2 in the presence of CO results in reduction of the metal center by four electrons from Re(V) to Re(I).}, number={17}, journal={ORGANOMETALLICS}, publisher={American Chemical Society (ACS)}, author={Lambic, Nikola S. and Lilly, Cassandra P. and Robbins, Leanna K. and Sommer, Roger D. and Ison, Elon A.}, year={2016}, month={Sep}, pages={2822–2829} }
 @article{lambic_sommer_ison_2016, title={Transition-Metal Oxos as the Lewis Basic Component of Frustrated Lewis Pairs}, volume={138}, ISSN={["1520-5126"]}, DOI={10.1021/jacs.6b00705}, abstractNote={The reaction of oxorhenium complexes that incorporate diamidopyridine (DAP) ligands with B(C6F5)3 results in the formation of classical Lewis acid-base adducts. The adducts effectively catalyze the hydrogenation of a variety of unactivated olefins at 100 °C. Control reactions with these complexes or B(C6F5)3 alone did not yield any hydrogenated products under these conditions. Mechanistic studies suggest a frustrated Lewis pair is generated between the oxorhenium DAP complexes and B(C6F5)3, which is effective at olefin hydrogenation. Thus, we demonstrate for the first time that the incorporation of a transition-metal oxo in a frustrated Lewis pair can have a synergistic effect and results in enhanced catalytic activity.}, number={14}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, publisher={American Chemical Society (ACS)}, author={Lambic, Nikola S. and Sommer, Roger D. and Ison, Elon A.}, year={2016}, month={Apr}, pages={4832–4842} }
 @article{lehman_pahls_meredith_sommer_heinekey_cundari_ison_2015, title={Oxyfunctionalization with Cp*Ir-III(NHC)(Me)(CI) with O-2: Identification of a Rare Bimetallic Ir-IV mu-Oxo Intermediate}, volume={137}, ISSN={["0002-7863"]}, DOI={10.1021/ja512905t}, abstractNote={Methanol formation from [Cp*Ir(III)(NHC)Me(CD2Cl2)](+) occurs quantitatively at room temperature with air (O2) as the oxidant and ethanol as a proton source. A rare example of a diiridium bimetallic complex, [(Cp*Ir(NHC)Me)2(μ-O)][(BAr(F)4)2], 3, was isolated and shown to be an intermediate in this reaction. The electronic absorption spectrum of 3 features a broad observation at ∼660 nm, which is primarily responsible for its blue color. In addition, 3 is diamagnetic and can be characterized by NMR spectroscopy. Complex 3 was also characterized by X-ray crystallography and contains an Ir(IV)-O-Ir(IV) core in which two d(5) Ir(IV) centers are bridged by an oxo ligand. DFT and MCSCF calculations reveal several important features of the electronic structure of 3, most notably, that the μ-oxo bridge facilitates communication between the two Ir centers, and σ/π mixing yields a nonlinear arrangement of the μ-oxo core (Ir-O-Ir ∼ 150°) to facilitate oxygen atom transfer. The formation of 3 results from an Ir oxo/oxyl intermediate that may be described by two competing bonding models, which are close in energy and have formal Ir-O bond orders of 2 but differ markedly in their electronic structures. The radical traps TEMPO and 1,4-cyclohexadiene do not inhibit the formation of 3; however, methanol formation from 3 is inhibited by TEMPO. Isotope labeling studies confirmed the origin of the methyl group in the methanol product is the iridium-methyl bond in the [Cp*Ir(NHC)Me(CD2Cl2)][BAr(F)4] starting material. Isolation of the diiridium-containing product [(Cp*Ir(NHC)Cl)2][(BAr(F)4)2], 4, in high yields at the end of the reaction suggests that the Cp* and NHC ligands remain bound to the iridium and are not significantly degraded under reaction conditions.}, number={10}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Lehman, Matthew C. and Pahls, Dale R. and Meredith, Joseph M. and Sommer, Roger D. and Heinekey, D. Michael and Cundari, Thomas R. and Ison, Elon A.}, year={2015}, month={Mar}, pages={3574–3584} }
 @article{robbins_lilly_smeltz_boyle_ison_2015, title={Synthesis and Reactivity of Oxorhenium (V) Methyl, Benzyl, and Phenyl Complexes with CO: Implications for a Unique Mechanism for Migratory Insertion.}, volume={34}, DOI={https://doi.org/10.1021/acs.organomet.5b00177}, abstractNote={The complexes [(DAAm)Re(O)(R)] [DAAm = N,N-bis(2-arylaminoethyl)methylamine; aryl = C6F5], 1, R = Me; 3a–d (R = benzyl, a; 4-methylbenzyl, b; 4-fluorobenzyl, c; 4-methoxybenzyl, d); and 4, R = Ph, were synthesized. CO insertion into the Re–R bond in 1 and 3a–d resulted in the formation of the acetyl complex, 2, and the (aryl)acetyl complexes, 5a–d respectively. The formation of 5a–d proceeded at a faster rate (7 h) than the formation of 2 (72 h) under the same conditions. No reaction was observed however for the phenyl complex 4 with CO. Kinetics for CO insertion into the various Re–R bonds were examined, and the experimental rate law was determined to be Rate = kobs[Re][CO]. The activation parameters for CO insertion into 1 and 3a were determined to be ΔG⧧(298 K) = 24(1). The enthalpy of activation ΔH⧧ was determined to be 9(1) and 10(3) kcal/mol for 1 and 3a, respectively, and the entropy of activation, ΔS⧧, was −49(2) and −36(4) cal/mol·K. Computational studies (M06) are consistent with the hypothesis that the rate of CO insertion is dependent on the strength of the rhenium–carbon bond. Thus, experimental and computational data suggest that the most likely mechanism for the insertion of CO into the Re–R bond in oxorhenium complexes is a direct-insertion mechanism.}, number={13}, journal={Organometallics}, publisher={American Chemical Society}, author={Robbins, L.K. and Lilly, C.P. and Smeltz, J.L. and Boyle, P.D. and Ison, E.A.}, year={2015}, month={Jul}, pages={3152–3158} }
 @article{robbins_lilly_smeltz_boyle_ison_2015, title={Synthesis and Reactivity of Oxorhenium(V) Methyl, Benzyl, and Phenyl Complexes with CO: Implications for a Unique Mechanism for Migratory Insertion}, volume={34}, ISSN={["1520-6041"]}, DOI={10.1021/acs.organomet.5b00177}, abstractNote={The complexes [(DAAm)Re(O)(R)] [DAAm = N,N-bis(2-arylaminoethyl)methylamine; aryl = C6F5], 1, R = Me; 3a–d (R = benzyl, a; 4-methylbenzyl, b; 4-fluorobenzyl, c; 4-methoxybenzyl, d); and 4, R = Ph, were synthesized. CO insertion into the Re–R bond in 1 and 3a–d resulted in the formation of the acetyl complex, 2, and the (aryl)acetyl complexes, 5a–d respectively. The formation of 5a–d proceeded at a faster rate (7 h) than the formation of 2 (72 h) under the same conditions. No reaction was observed however for the phenyl complex 4 with CO. Kinetics for CO insertion into the various Re–R bonds were examined, and the experimental rate law was determined to be Rate = kobs[Re][CO]. The activation parameters for CO insertion into 1 and 3a were determined to be ΔG⧧(298 K) = 24(1). The enthalpy of activation ΔH⧧ was determined to be 9(1) and 10(3) kcal/mol for 1 and 3a, respectively, and the entropy of activation, ΔS⧧, was −49(2) and −36(4) cal/mol·K. Computational studies (M06) are consistent with the hypothesis ...}, number={13}, journal={ORGANOMETALLICS}, author={Robbins, Leanna K. and Lilly, Cassandra P. and Smeltz, Jessica L. and Boyle, Paul D. and Ison, Elon A.}, year={2015}, month={Jul}, pages={3152–3158} }
 @article{frasco_sommer_ison_2015, title={ortho-C–H Activation of Thiobenzoic Acid: Synthesis, Characterization, and Reactivity of Iridium Thiobenzoate Complexes}, volume={34}, ISSN={["1520-6041"]}, DOI={10.1021/om501115u}, abstractNote={Cp*Ir(Me2SO)(OAc)2, 1, has been shown to activate an ortho-C–H-bond of thiobenzoic acid in methanol at 100 °C to form the novel iridium complex (Cp*Ir(S(O)CC6H4))2, 5. Unlike the similar reaction with benzoic acid, this new iridium complex exists as a dimer with bridging sulfur ligands. To our knowledge, this is the first example of metal facilitated C–H activation of thiobenzoic acid. Complex 5 reacted with CO to form Cp*Ir(CO)(S(O)CC6H4), 6. Complex 5 was also shown to react with the electrophilic methyl reagents methyl iodide and methyl triflate. The reaction with methyl iodide resulted in the formation of Cp*Ir(I)(SMe(O)CC6H4), 7, while the reaction with methyl triflate resulted in the bimetallic complex [(Cp*Ir(SMe(O)CC6H4)(Cp*Ir(S(O)CC6H4)][OTf], 8. The order of reactivity with electrophilic methyl reagents was MeOTf > MeI >MeOAc, which reflects the nucleophilic character of the sulfoxyl group of the cyclometalated thiobenzoate ligand. Attempts at cyclization with complex 5 and olefins and alkynes w...}, number={1}, journal={Organometallics}, publisher={American Chemical Society (ACS)}, author={Frasco, D.A. and Sommer, R.D. and Ison, E.A.}, year={2015}, pages={275–279} }
 @article{lehman_boyle_sommer_ison_2014, title={Oxyfunctionalization with Cp*Ir-III(NHC)(Me)L Complexes}, volume={33}, ISSN={["1520-6041"]}, DOI={10.1021/om5007352}, abstractNote={A series of monomethyl Cp*IrIII complexes were synthesized and studied for the formation of methanol in water. Methanol yields of 75(4)% in the presence of O2 were obtained. From isotope labeling studies, it was determined that O2 is the source of the oxygen atom in the product. From kinetic studies, oxyfunctionalization appears to proceed by dissociation of an L-type ligand followed by O2 binding and insertion.}, number={19}, journal={ORGANOMETALLICS}, publisher={American Chemical Society (ACS)}, author={Lehman, Matthew C. and Boyle, Paul D. and Sommer, Roger D. and Ison, Elon A.}, year={2014}, month={Oct}, pages={5081–5084} }
 @article{frasco_lilly_boyle_ison_2013, title={Cp*Ir-III-Catalyzed Oxidative Coupling of Benzoic Acids with Alkynes}, volume={3}, ISSN={["2155-5435"]}, DOI={10.1021/cs400656q}, abstractNote={Cp*Ir(III) complexes have been shown to catalyze the oxidative coupling of benzoic acids with alkynes in methanol at 60 °C to form a variety of isocoumarins. The use of AgOAc as an oxidant was required to facilitate significant product formation. Alkyl alkynes were shown to be more reactive substrates than aryl alkynes, and a number of functional groups were tolerated on benzoic acid. Combined mechanistic and computational studies (BP86) revealed that (1) C–H activation occurs via an acetate-assisted mechanism; (2) C–H activation is not turnover limiting; and (3) the oxidant oxidizes the reduced form of the catalyst via an Ir(I)–Ir(II)–Ir(III) sequence.}, number={10}, journal={ACS CATALYSIS}, author={Frasco, Daniel A. and Lilly, Cassandra P. and Boyle, Paul D. and Ison, Elon A.}, year={2013}, month={Oct}, pages={2421–2429} }
 @article{lehman_gary_boyle_sanford_ison_2013, title={Effect of Solvent and Ancillary Ligands on the Catalytic H/D Exchange Reactivity of Cp*Ir-III(L) Complexes}, volume={3}, ISSN={["2155-5435"]}, DOI={10.1021/cs400420n}, abstractNote={The reactivity of a series of Cp*IrIII(L) complexes that contain a diverse set of ancillary ligands, L, (L = PMe3, N-heterocyclic carbene, NHC = 1,3-dimethylimidazol-2-ylidene, aqua, 4-t-butylpyridine, and 4-(2,4,6-tris-(4-t-butylphenyl)pyridinium)pyridine tetrafluoroborate) has been examined in catalytic H/D exchange reactions between C6H6 and a series of deuterated solvents (methanol-d4, acetic acid-d4, and trifluoroacetic acid-d1). These studies demonstrate that (1) the mechanism of catalytic H/D exchange is significantly influenced by the nature of the solvent; (2) electron-donating ligands (PMe3, NHC) promote the formation of Ir hydrides in methanol-d4, and these are critical intermediates in catalytic H/D exchange processes; and (3) weak/poorly donating ligands (4-t-butylpyridine, 4-(2,4,6-tris-(4-t-butylphenyl)pyridinium)pyridine tetrafluoroborate and aqua) can support efficient H/D exchange catalysis in acetic acid-d4.}, number={10}, journal={ACS CATALYSIS}, author={Lehman, Matthew C. and Gary, J. Brannon and Boyle, Paul D. and Sanford, Melanie S. and Ison, Elon A.}, year={2013}, month={Oct}, pages={2304–2310} }
 @article{liu_senocak_smeltz_yang_wegenhart_yi_kenttaemaa_ison_abu-omar_2013, title={Mechanism of MTO-Catalyzed Deoxydehydration of Diols to Alkenes Using Sacrificial Alcohols}, volume={32}, ISSN={["1520-6041"]}, DOI={10.1021/om400127z}, abstractNote={Catalytic deoxydehydration (DODH) of vicinal diols is carried out employing methyltrioxorhenium (MTO) as the catalyst and a sacrificial alcohol as the reducing agent. The reaction kinetics feature an induction period when MTO is added last and show zero-order in [diol] and half-order dependence on [catalyst]. The rate-determining step involves reaction with alcohol, as evidenced by a KIE of 1.4 and a large negative entropy of activation (ΔS‡ = −154 ± 33 J mol–1 K–1). The active form of the catalyst is methyldioxorhenium(V) (MDO), which is formed by reduction of MTO by alcohol or via a novel C–C bond cleavage of an MTO-diolate complex. The majority of the MDO-diolate complex is present in dinuclear form, giving rise to the [Re]1/2 dependence. The MDO-diolate complex undergoes further reduction by alcohol in the rate-determining step to give rise to a putative rhenium(III) diolate. The latter is the active species in DODH extruding stereoselectively trans-stilbene from (R,R)-(+)-hydrobenzoin to regenerate M...}, number={11}, journal={ORGANOMETALLICS}, author={Liu, Shuo and Senocak, Aysegul and Smeltz, Jessica L. and Yang, Linan and Wegenhart, Benjamin and Yi, Jing and Kenttaemaa, Hilkka I. and Ison, Elon A. and Abu-Omar, Mandi M.}, year={2013}, month={Jun}, pages={3210–3219} }
 @article{smeltz_lilly_boyle_ison_2013, title={The Electronic Nature of Terminal Oxo Ligands in Transition-Metal Complexes: Ambiphilic Reactivity of Oxorhenium Species}, volume={135}, ISSN={["1520-5126"]}, DOI={10.1021/ja401390v}, abstractNote={The synthesis of the Lewis acid-base adducts of B(C6F5)3 and BF3 with [DAAmRe(O)(X)] DAAm = N,N-bis(2-arylaminoethyl)methylamine; aryl = C6F5 (X = Me, 1, COCH3, 2, Cl, 3) as well as their diamidopyridine (DAP) (DAP=(2,6-bis((mesitylamino)methyl)pyridine) analogues, [DAPRe(O)(X)] (X = Me, 4, Cl, 5, I, 6, and COCH3,7), are described. In these complexes the terminal oxo ligands act as nucleophiles. In addition we also show that stoichiometric reactions between 3 and triarylphosphine (PAr3) result in the formation of triarylphosphine oxide (OPAr3). The electronic dependence of this reaction was studied by comparing the rates of oxygen atom transfer for various para-substituted triaryl phosphines in the presence of CO. From these experiments a reaction constant ρ = -0.29 was obtained from the Hammett plot. This suggests that the oxygen atom transfer reaction is consistent with nucleophilic attack of phosphorus on an electrophilic metal oxo. To the best of our knowledge, these are the first examples of mono-oxo d(2) metal complexes in which the oxo ligand exhibits ambiphilic reactivity.}, number={25}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Smeltz, Jessica L. and Lilly, Cassandra P. and Boyle, Paul D. and Ison, Elon A.}, year={2013}, month={Jun}, pages={9433–9441} }
 @article{smeltz_webster_ison_2012, title={Computational Investigation of the Mechanism for the Activation of CO by Oxorhenium Complexes}, volume={31}, ISSN={["0276-7333"]}, DOI={10.1021/om3003366}, abstractNote={In this paper a computational analysis (B3PW91) of the previously reported reaction of (O)Re(Me)(DAAm) (1; DAAm = N,N-bis(2-arylaminoethyl)methylamine, aryl = C6F5) with CO to produce (CO)Re(OAc)(DAAm) (2) is described. The data suggest that this transformation proceeds by two novel elementary steps that are of fundamental interest to the broader organometallic/inorganic community: (a) direct insertion of CO into the rhenium–methyl bond in 1 to yield the acyl intermediate (O)Re(Ac)(DAAm) (3) and (b) 1,2-migration, in the presence of CO, of the acyl fragment in 3 to the oxo ligand to yield 2. Evidence is provided for the first example of an insertion reaction where CO inserts directly into a M–R bond without prior formation of a CO adduct. In addition, it was shown that the addition of CO is necessary for the 1,2-migration of the acyl ligand. The data suggest that the addition of CO effectively weakens the Re–Cacyl bond in 3 and enables the facile migration of the acyl ligand.}, number={10}, journal={ORGANOMETALLICS}, author={Smeltz, Jessica L. and Webster, Charles Edwin and Ison, Elon A.}, year={2012}, month={May}, pages={4055–4062} }
 @article{smeltz_boyle_ison_2012, title={Role of Low-Valent Rhenium Species in Catalytic Hydrosilylation Reactions with Oxorhenium Catalysts}, volume={31}, ISSN={["0276-7333"]}, DOI={10.1021/om300654q}, abstractNote={The catalytic competency of a Re(III) complex has been demonstrated. In the presence of silane, oxorhenium(V) catalysts are deoxygenated to produce species that are significantly more active than t...}, number={17}, journal={ORGANOMETALLICS}, author={Smeltz, Jessica L. and Boyle, Paul D. and Ison, Elon A.}, year={2012}, month={Sep}, pages={5994–5997} }
 @article{lilly_boyle_ison_2012, title={Synthesis of Oxorhenium Acetyl and Benzoyl Complexes Incorporating Diamidopyridine Ligands: Implications for the Mechanism of CO Insertion}, volume={31}, ISSN={["0276-7333"]}, DOI={10.1021/om3002872}, abstractNote={A series of oxorhenium alkyl, phenyl, and vinyl complexes of the form [(DAP)Re(O)(R)] (R = aryl, vinyl, alkyl) was reported, and their reactivity with CO was examined. The methyl complex 5a reacts with CO at a significantly faster rate (2.5 h) than the phenyl complex 7a (24 h). Computational (B3PW91) studies reveal that although the acyl complex is the least stable (ΔG353 = −11.2 kcal/mol) with respect to CO insertion compared to the benzoyl complex (ΔG353 = −14.5 kcal/mol), the activation energy for CO insertion is lower for the methyl complex (ΔG⧧353 = 14.6 kcal/mol) than for the phenyl complex (ΔG⧧353 = 17.4 kcal/mol). This is consistent with the previously proposed mechanism, where CO inserts directly into the Re–R bond without prior formation of a CO adduct. The X-ray crystal structures of complexes 6, 7a, 8a, and 9a are reported.}, number={11}, journal={ORGANOMETALLICS}, author={Lilly, Cassandra P. and Boyle, Paul D. and Ison, Elon A.}, year={2012}, month={Jun}, pages={4295–4301} }
 @article{ison_ison_2012, title={Synthesis of Well-Defined Copper N-Heterocyclic Carbene Complexes and Their Use as Catalysts for a “Click Reaction”: A Multistep Experiment That Emphasizes the Role of Catalysis in Green Chemistry}, volume={89}, ISSN={0021-9584 1938-1328}, url={http://dx.doi.org/10.1021/ed300243s}, DOI={10.1021/ed300243s}, abstractNote={A multistep experiment for an advanced synthesis lab course that incorporates topics in organic–inorganic synthesis and catalysis and highlights green chemistry principles was developed. Students synthesized two N-heterocyclic carbene ligands, used them to prepare two well-defined copper(I) complexes and subsequently utilized the complexes as catalysts in the Huisgen 1-3 dipolar cycloaddition of benzyl azide and phenylacetylene. The catalytic reaction exhibits high atom economy, is performed without a solvent at room temperature, and is high yielding. Thus, students were able to practice and apply concepts of green chemistry through catalysis. In the process of preparing ligands and complexes, several techniques were utilized that were aimed at performing reactions more efficiently (microwave experiments) or performing reactions in benign solvents (H2O). Another major component of this experiment is emphasis on technical writing through student preparation of formal communications and full paper using the...}, number={12}, journal={Journal of Chemical Education}, publisher={American Chemical Society (ACS)}, author={Ison, Elon A. and Ison, Ana}, year={2012}, month={Oct}, pages={1575–1577} }
 @article{engelman_feng_ison_2011, title={C-H Bond Functionalization of Benzoic Acid: Catalytic Synthesis of 2-Hydroxy-6H-benzo[c]chromen-6-ones Using (Cp*IrCl2)(2)}, volume={30}, ISSN={["1520-6041"]}, DOI={10.1021/om200343b}, abstractNote={Catalytic H/D exchange reactions of benzene and benzoic acid with deuterated solvents have been studied using (Cp*IrCl2)2. A 1:1 mixture of D2O/CD3OD produced the highest turnover numbers for benzene. High levels of deuterium incorporation into benzoic acid were observed only when sodium acetate was added to the reaction mixture. Attempts at producing hydroxybenzoic acid by catalytic C–H functionalization of benzoic acid with benzoquinone were unsuccessful. Instead, 2-hydroxy-6H-benzo[c]chromen-6-one was isolated as the major product. An array of substituted benzoic acids was analyzed for this functionalization reaction. Preliminary mechanistic studies indicate that the benzochromenones are formed by C–H bond activation of benzoic acid followed by insertion of benzoquinone into the iridium–carbon bond.}, number={17}, journal={ORGANOMETALLICS}, author={Engelman, Kristi L. and Feng, Yuee and Ison, Elon A.}, year={2011}, month={Sep}, pages={4572–4577} }
 @article{smeltz_boyle_ison_2011, title={Mechanism for the Activation of Carbon Monoxide via Oxorhenium Complexes}, volume={133}, ISSN={["0002-7863"]}, DOI={10.1021/ja205477w}, abstractNote={Activation of CO by the rhenium(V) oxo complex [(DAAm)Re(O)(CH(3))] (1) [DAAm = N,N-bis(2-arylaminoethyl)methylamine; aryl = C(6)F(5), Mes] resulted in the isolation of the rhenium(III) acetate complex [(DAAm)Re(O(2)CCH(3))(CO)] (3). The mechanistic details of this reaction were explored experimentally. The novel oxorhenium(V) acyl intermediate [(DAAm)Re(O)(C(O)CH(3))] (2) was isolated, and its reactivity with CO was investigated. An unprecedented mechanism is proposed: CO is activated by the metal oxo complex 1 and inserted into the rhenium-methyl bond to yield acyl complex 2, after which subsequent migration of the acyl ligand to the metal oxo ligand yields acetate complex 3. X-ray crystal structures of 2 and 3 are reported.}, number={34}, journal={JOURNAL OF THE AMERICAN CHEMICAL SOCIETY}, author={Smeltz, Jessica L. and Boyle, Paul D. and Ison, Elon A.}, year={2011}, month={Aug}, pages={13288–13291} }
 @article{travia_xu_keith_ison_fanwick_hall_abu-omar_2011, title={Observation of Inductive Effects That Cause a Change in the Rate-Determining Step for the Conversion of Rhenium Azides to Imido Complexes}, volume={50}, ISSN={0020-1669 1520-510X}, url={http://dx.doi.org/10.1021/ic2017853}, DOI={10.1021/ic2017853}, abstractNote={The cationic oxorhenium(V) complex [Re(O)(hoz)(2)(CH(3)CN)][B(C(6)F(5))(4)] [1; Hhoz = 2-(2'-hydroxyphenyl)-2-oxazoline] reacts with aryl azides (N(3)Ar) to give cationic cis-rhenium(VII) oxoimido complexes of the general formula [Re(O)(NAr)(hoz)(2)][B(C(6)F(5))(4)] [2a-2f; Ar = 4-methoxyphenyl, 4-methylphenyl, phenyl, 3-methoxyphenyl, 4-chlorophenyl, and 4-(trifluoromethyl)phenyl]. The kinetics of formation of 2 in CH(3)CN are first-order in both azide (N(3)Ar) and oxorhenium(V) complex 1, with second-order rate constants ranging from 3.5 × 10(-2) to 1.7 × 10(-1) M(-1) s(-1). A strong inductive effect is observed for electron-withdrawing substituents, leading to a negative Hammett reaction constant ρ = -1.3. However, electron-donating substituents on phenyl azide deviate significantly from this trend. Enthalpic barriers (ΔH(‡)) determined by the Eyring-Polanyi equation are in the range 14-19 kcal mol(-1) for all aryl azides studied. However, electron-donating 4-methoxyphenyl azide exhibits a large negative entropy of activation, ΔS(‡) = -21 cal mol(-1) K(-1), which is in sharp contrast to the near zero ΔS(‡) observed for phenyl azide and 4-(trifluoromethyl)phenyl azide. The Hammett linear free-energy relationship and the activation parameters support a change in the mechanism between electron-withdrawing and electron-donating aryl azides. Density functional theory predicts that the aryl azides coordinate via N(α) and extrude N(2) directly. For the electron-withdrawing substituents, N(2) extrusion is rate-determining, while for the electron-donating substituents, the rate-determining step becomes the initial attack of the azide. The barriers for these two steps are inverted in their order with respect to the Hammett σ values; thus, the Hammett plot appears with a break in its slope.}, number={20}, journal={Inorganic Chemistry}, publisher={American Chemical Society (ACS)}, author={Travia, Nicholas E. and Xu, Zhenggang and Keith, Jason M. and Ison, Elon A. and Fanwick, Phillip E. and Hall, Michael B. and Abu-Omar, Mahdi M.}, year={2011}, month={Oct}, pages={10505–10514} }
 @article{lilly_boyle_ison_2011, title={Synthesis and characterization of oxorhenium(V) diamido pyridine complexes that catalyze oxygen atom transfer reactions}, volume={40}, ISSN={["1477-9226"]}, DOI={10.1039/c1dt11143d}, abstractNote={The detailed syntheses of complexes 1-4, Re(O)(X)(DAP) (X = Me, 1; Cl, 2; I, 3; OTf (triflate), 4) incorporating the diamido pyridine (DAP) ancillary ligand (2,6-bis((mesitylamino)methyl)pyridine) are described and shown to be effective catalysts for oxygen atom transfer (OAT) reactions of PyO to PPh(3). The catalytic activities are as follows: 4≈3 > 2 > 1. The observed electronic trend is consistent with the turnover limiting reduction of the proposed Re(VII) dioxo intermediate, Re(O)(2)(X)(DAP), during the catalytic cycle. The catalytic activity of complexes 1-3 was compared to previously published diamido amine (DAAm) oxorhenium complexes of the type Re(O)(X)(DAAm) (X = Me, 5; Cl, 6; I, 7 and DAAm = N,N-bis(2-arylaminoethyl)methylamine) which exhibit hydrolytic degradation during the catalytic reaction. Complexes 1-3 displayed higher turnover frequencies compared to 5-7. This higher catalytic activity was attributed to the more rigid DAP ligand backbone, which makes the complexes less susceptible to decomposition. However, another decomposition pathway was proposed for this catalytic system due to the observation of Re(O)(3)((MesNCH(2))(MesNCH)NC(5)H(3)) 8 in which one arm of the DAP ligand is oxidized.}, number={44}, journal={DALTON TRANSACTIONS}, author={Lilly, Cassandra P. and Boyle, Paul D. and Ison, Elon A.}, year={2011}, pages={11815–11821} }
 @article{feng_jiang_boyle_ison_2010, title={Effect of Ancillary Ligands and Solvents on H/D Exchange Reactions Catalyzed by Cp*Ir Complexes}, volume={29}, ISSN={["1520-6041"]}, DOI={10.1021/om100018x}, abstractNote={A series of complexes of the form Cp*Ir(NHC)(X)n and [Cp*Ir(NHC)(L)2][OTf]2, where NHC = 1,3,4,5-tetramethylimidazol-2-ylidene (n = 2, X = Cl− (1-Cl), NO3− (1-NO3), −OC(O)CF3 (=TFA, 1-TFA); n = 1, X = SO42− (1-SO4); L = H2O (1-H2O), CH3CN (1-CH3CN), OTf = trifluoromethanesulfonato), were prepared. X-ray crystal structures of 1-OH2, 1-SO4, and 1-NO3 and the dimeric complex [(Cp*Ir(NHC)Cl)2][OTf]2 (2) were obtained. In solution, the complex 1-TFA was found to exist in equilibrium with [Cp*Ir(NHC)(OH2)2][OCOCF3]2 (1-aqua-TFA), where the aqua ligands are strongly hydrogen bound to the −OCOCF3 counterion. A van’t Hoff plot from −10 to 30 °C yielded values for the reaction enthalpy and entropy of ΔH° = −7.6 ± 0.7 kcal/mol and ΔS° = −30.6 ± 2.4 eu, respectively. These data are consistent with the observation that at higher temperatures the complex 1-TFA is favored. An X-ray crystal structure of 1-aqua-TFA was obtained. Catalytic H/D exchange reactions between benzene and various deuterium sources (CD3OD, CF3COOD...}, number={13}, journal={ORGANOMETALLICS}, author={Feng, Yuee and Jiang, Bi and Boyle, Paul A. and Ison, Elon A.}, year={2010}, month={Jul}, pages={2857–2867} }
 @article{corbin_ison_abu-omar_2009, title={Catalysis by cationic oxorhenium(v): hydrolysis and alcoholysis of organic silanes}, volume={15}, ISSN={1477-9226 1477-9234}, url={http://dx.doi.org/10.1039/b822783g}, DOI={10.1039/b822783g}, abstractNote={The cationic [2-(2'-hydroxyphenyl)-2-oxazolinato(-2)]oxorhenium(v) complex promotes oxidative dehydrogenation of organosilanes with water and alcohols in a catalytic manner to give excellent yields of silanols and silyl ethers, respectively. The reactions proceed conveniently under ambient and open-flask conditions with low catalyst loading (<or=1 mol%). The scope of the reaction with water is quite broad and includes aliphatic, aromatic, tertiary, secondary and primary silanes. The rate of reaction depends on the catalyst and silane concentrations and kinetic isotope effect measurements demonstrate involvement of the Si-H bond in the activated complex. The most influential factor on the silane affecting reactivity is steric hindrance and a quantitative correlation with the Taft steric parameter (E) is presented. A combination of kinetic data and isotope labelling results are used to discuss plausible mechanisms for the oxidative dehydrogenation reaction pathway.}, number={15}, journal={Dalton Transactions}, publisher={Royal Society of Chemistry (RSC)}, author={Corbin, Rex A. and Ison, Elon A. and Abu-Omar, Mahdi M.}, year={2009}, pages={2850–2855} }
 @article{feng_aponte_houseworth_boyle_ison_2009, title={Synthesis of Oxorhenium(V) Complexes with Diamido Amine Ancillary Ligands and Their Role in Oxygen Atom Transfer Catalysis}, volume={48}, ISSN={["1520-510X"]}, DOI={10.1021/ic901434u}, abstractNote={The detailed syntheses of complexes of the form [Re(O)(X)(RNCH(2)CH(2))(2)N(Me)] (X = Me, Cl, I, R = mesityl, C(6)F(5)), 1-3, incorporating diamidoamine ancillary ligands are described. X-ray crystal structures for the complexes [Re(O)(Me)((C(6)F(5))NCH(2)CH(2))(2)N(Me)], 1a, [Re(O)(I)((C(6)F(5))N CH(2)CH(2))(2)N(Me)], 3a, and [Re(O)(I)((Mes)NCH(2))(2)N(Me)], 3b, are reported. The geometry about the metal center in 1a is best described as a severely distorted square pyramid with the oxo ligand in the apical position. In contrast, the geometry about the metal center in 3a is best described as a severely distorted trigonal bipyramid, with the iodo ligand occupying the apical position and the diamido nitrogens and the oxo ligand occupying the equatorial plane. The catalytic activities of these complexes for oxygen atom transfer, OAT, from pyridine-N-oxides, PyO, to PPh(3) were also examined. The reactions exhibited a clear dependence on the diamido ligand substituent and the X ligand (Me, I, Cl) attached to the metal, with the combined effect that electron-withdrawing substituents on the diamido ligand and poor sigma donors directly attached to the metal center increases the rate of catalytic activity. The kinetics of OAT from pyridine-N-oxides to Re were also investigated. The reactions displayed clean first order kinetics in Re and saturation kinetics for the dependence on PyO. Changing the PyO substrate had no effect on the saturation value, k(sat), suggesting that the OAT reaction in these five-coordinate complexes appears to be governed by isomerization of the starting complex. Attempts to isolate a postulated Re(VII) intermediate were not successful because of hydrolytic degradation. The product of hydrolytic degradation [((C(6)F(5))N(H)CH(2)CH(2)))(2)NH(Me)][X], (X = ReO(4)(-), or I(-)), 4 can be isolated, and its X-ray crystal structure is reported. Although the Re(VII) intermediate could not be isolated, its activity in OAT reactions was probed by competition experiments with PPh(3) and four para-substituted triarylphosphines (p-X-Ph)(3)P (X = OMe, Me, Cl, CF(3)). These experiments led to a Hammett that yielded a reaction constant of rho = -0.30 +/- 0.01. This data suggests a positive charge buildup on phosphorus for the OAT reaction and is consistent with the nucleophilic attack of phosphorus on an electrophilic metal oxo.}, number={23}, journal={INORGANIC CHEMISTRY}, author={Feng, Yuee and Aponte, Joel and Houseworth, Paul J. and Boyle, Paul D. and Ison, Elon A.}, year={2009}, month={Dec}, pages={11058–11066} }
 @article{jiang_feng_ison_2008, title={Mechanistic Investigations of the Iridium(III)-Catalyzed Aerobic Oxidation of Primary and Secondary Alcohols}, volume={130}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja8049595}, DOI={10.1021/ja8049595}, abstractNote={The commercially available catalysts [(Cp*IrCl2)2] is employed with O2 as the terminal oxidant in the presence of catalytic amounts of Et3N for the aerobic oxidation of primary and secondary alcohols. A new mechanism for the Ir-catalyzed aerobic oxidation is also presented that suggests that the transition metal maintains its +3 oxidation state throughout the entire catalytic cycle.}, number={44}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Jiang, Bi and Feng, Yuee and Ison, Elon A.}, year={2008}, month={Nov}, pages={14462–14464} }
 @article{ison_cessarich_travia_fanwick_abu-omar_2007, title={Synthesis of Cationic Rhenium(VII) Oxo Imido Complexes and Their Tunability Towards Oxygen Atom Transfer}, volume={129}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja065551p}, DOI={10.1021/ja065551p}, abstractNote={A facile method is described for the synthesis of cationic Re(VII) cis oxo imido complexes of the form [Re(O)(NAr)(salpd)+] (salpd = N,N'-propane-1,3-diylbis(salicylideneimine)), 4, [Re(O)(NAr)(saldach)+] (saldach = N,N'-cyclohexane-1,3-diylbis(salicylideneimine)), 5, and [Re(O)(NAr)(hoz)2+] (hoz = 2-(2'-hydroxyphenyl)-2-oxazoline) (Ar = 2,4,6,-(Me)C(6)H(2); 4-(OMe)C(6)H(4); 4-(Me)C(6)H(4); 4-(CF3)C6H4; 4-MeC(6)H(4)SO(2)), 6, from the reaction of oxorhenium(V) [(L)Re(O)(Solv)+] (1-3) and aryl azides under ambient conditions. Unlike previously reported cationic Re(VII) dioxo complexes, these cationic oxo imido complexes can be obtained on a preparative scale, and an X-ray crystal structure of [Re(O)(NMes)(saldach)+], 5a, has been obtained. Despite the multiple stereoisomers that could arise from tetradentate ligation of salen ligands to rhenium, one major isomer is observed and isolated in each instant. The electronic rationalization for stereoselectivity is discussed. Investigation of the mechanism suggests that the reactions of Re(V) with aryl azides proceed through an azido adduct similar to the group 5 complexes of Bergman and Cummins. Treatment of the cationic oxo imido complexes with a reductant (PAr(3), PhSMe, or PhSH) results in oxygen atom transfer (OAT) and the formation of cationic Re(V) imido complexes. [(salpd)Re(NMes)(PPh(3))(+)] (7) and [(hoz)2Re(NAr)(PPh(3))(+)] (Ar = m-OMe phenyl) (9) have been isolated on a preparative scale and fully characterized including an X-ray single-crystal structure of 7. The kinetics of OAT, monitored by stopped-flow spectroscopy, has revealed rate saturation for substrate dependences. The different plateau values for different oxygen acceptors (Y) provide direct support for a previously suggested mechanism in which the reductant forms a prior-equilibrium adduct with the rhenium oxo (ReVII = O<--Y). The second-order rate constants of OAT, which span more than 3 orders of magnitude for a given substrate, are significantly affected by the electronics of the imido ancillary ligand with electron-withdrawing imidos being most effective. However, the rate constant for the most active oxo imido rhenium(VII) is 2 orders of magnitude slower than that observed for the known cationic dioxo Re(VII) [(hoz)2Re(O)(2)(+)].}, number={5}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Ison, Elon A. and Cessarich, Jeanette E. and Travia, Nicholas E. and Fanwick, Phillip E. and Abu-Omar, Mahdi M.}, year={2007}, month={Feb}, pages={1167–1178} }
 @article{ison_abboud_boncella_2006, title={Synthesis and Reactivity of Molybdenum Imido Diamido Metallacyclopentenes and Metallacyclopentadienes and the Mechanism of Ethylene Exchange with Metallacyclopentane Complexes}, volume={25}, ISSN={0276-7333 1520-6041}, url={http://dx.doi.org/10.1021/om050280x}, DOI={10.1021/om050280x}, abstractNote={In this paper the reactivity of the previously reported metallacyclopentane complex [Mo(NPh)(o-(Me3SiN)2C6H4)(CH2)4] (1) is reported. Complex 1 reacts with acetylenes via ethylene exchange to form ...}, number={7}, journal={Organometallics}, publisher={American Chemical Society (ACS)}, author={Ison, Elon A. and Abboud, Khalil A. and Boncella, James M.}, year={2006}, month={Mar}, pages={1557–1564} }
 @article{ison_cessarich_du_fanwick_abu-omar_2006, title={Synthesis of Cationic Oxorhenium Salen Complexes via μ-Oxo Abstraction and Their Activity in Catalytic Reductions}, volume={45}, ISSN={0020-1669 1520-510X}, url={http://dx.doi.org/10.1021/ic0520768}, DOI={10.1021/ic0520768}, abstractNote={Cationic oxorhenium salen complexes are prepared by the abstraction of bridging oxo ligands with [Et3Si][B(C6F5)4] and [Ph3C][B(C6F5)4]. These complexes catalyze the reduction of 2-butanone with Et3SiH under ambient conditions.}, number={6}, journal={Inorganic Chemistry}, publisher={American Chemical Society (ACS)}, author={Ison, Elon A. and Cessarich, Jeanette E. and Du, Guodong and Fanwick, Phillip E. and Abu-Omar, Mahdi M.}, year={2006}, month={Mar}, pages={2385–2387} }
 @article{ison_corbin_abu-omar_2005, title={Hydrogen Production from Hydrolytic Oxidation of Organosilanes Using a Cationic Oxorhenium Catalyst}, volume={127}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja053860u}, DOI={10.1021/ja053860u}, abstractNote={We describe herein the novel application of a transition metal oxo complex, a cationic oxorhenium(V) oxazoline, in the production of molecular hydrogen (H2) from the catalytic hydrolytic oxidation of organosilanes. The main highlights of the reaction are quantitative hydrogen yields, low catalyst loading, ambient conditions, high selectivity for silanols, water as the only co-reagent, and no solvent requirement. The amount of hydrogen produced is proportional to the water stoichiometry. Thus, reaction mixtures of polysilyl organics such as HC(SiH3)3 and water contain potentially >6 wt % hydrogen. Kinetic and isotope labeling experiments have revealed a new mechanistic paradigm for the activation of Si-H bonds by oxometalates.}, number={34}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Ison, Elon A. and Corbin, Rex A. and Abu-Omar, Mahdi M.}, year={2005}, month={Aug}, pages={11938–11939} }
 @article{ison_trivedi_corbin_abu-omar_2005, title={Mechanism for Reduction Catalysis by Metal Oxo:  Hydrosilation of Organic Carbonyl Groups Catalyzed by a Rhenium(V) Oxo Complex}, volume={127}, ISSN={0002-7863 1520-5126}, url={http://dx.doi.org/10.1021/ja055704t}, DOI={10.1021/ja055704t}, abstractNote={The rhenium oxo complex [Re(O)(hoz)2][TFPB], 1 (where hoz = 2-(2'-hydroxyphenyl)-2-oxazoline(-) and TFPB = tetrakis(pentafluorophenyl)borate) catalyzes the hydrosilation of aldehydes and ketones under ambient temperature and atmosphere. The major organic product is the protected alcohol as silyl ether. Isolated yields range from 86 to 57%. The reaction requires low catalyst loading (0.1 mol %) and proceeds smoothly in CH2Cl2 as well as neat without solvent. In the latter condition, the catalyst precipitates at the end of reaction, allowing easy separation and catalyst recycling. Re(O)(hoz)(H), 3, was prepared, and its involvement in an ionic hydrosilation mechanism was evaluated. Complex 3 was found to be less hydridic than Et3SiH, refuting its participation in catalysis. A viable mechanism that is consistent with experimental findings, rate measurements, and kinetic isotope effects (Et3SiH/Et3SiD = 1.3 and benzaldehyde-H/benzaldehyde-D = 1.0) is proposed. Organosilane is activated via eta2-coordination to rhenium, and the organic carbonyl adds across the coordinated Si-H bond [2 + 2] to afford the organic reduction product.}, number={44}, journal={Journal of the American Chemical Society}, publisher={American Chemical Society (ACS)}, author={Ison, Elon A. and Trivedi, Evan R. and Corbin, Rex A. and Abu-Omar, Mahdi M.}, year={2005}, month={Nov}, pages={15374–15375} }
 @article{ison_ortiz_abboud_boncella_2005, title={Synthesis and Reactivity of Molybdenum(IV) Complexes with Alkyl and Aryl Isocyanides}, volume={24}, ISSN={0276-7333 1520-6041}, url={http://dx.doi.org/10.1021/om0502436}, DOI={10.1021/om0502436}, abstractNote={The synthesis and characterization of the bis(isocyanide) complexes (RNC) 2 Mo(NPh)-(o-(Me 3 SiN) 2 C 6 H 4 ) (2: 2a, R = t BuNC; 2b, R = 2,6-dimethylphenyl) and the subsequent reactivity of these complexes with excess isocyanide have been reported. An X-ray crystal structure of (RNC)2Mo(NPh)(o-(Me3SiN)2C6H4) (R = 2,6-dimethylphenyl) is reported. Treatment of 2a with excess tert-butyl isocyanide resulted in the formation of the tris(isocyanide) complex (tBuNC)3Mo(NPh)(o-(Me3SiN)2C6H4) (3). Complex 3 exists in solution in equilibrium with 2a. Using a two-site exchange mechanism the activation barrier for the dissociative exchange of t BuNC has been calculated. The X-ray crystal structure of ( t BUNC) 3 Mo(NPh)-(o-(Me 3 SiN) 2 C 6 H 4 ) is reported. Computational studies (ONIOM) performed on 3 reveal that π conflicts in this complex results in the lengthening of the Mo-N(amido) c i s bond relative to the Mo-N(amido) t r a n s bond. Treatment of 2b with excess 2,6-dimethylphenyl isocyanide results in the slow insertion of the isocyanide ligands into the Mo-N bond of the chelating diamide ligand, resulting in a novel chelating iminocarbamoyl bis(isocyanide) complex, 4. An X-ray crystal structure of 4 is reported.}, number={26}, journal={Organometallics}, publisher={American Chemical Society (ACS)}, author={Ison, Elon A. and Ortiz, Carlos O. and Abboud, Khalil and Boncella, James M.}, year={2005}, month={Dec}, pages={6310–6318} }
 @article{ison_abboud_ghiviriga_boncella_2004, title={Alkyl aluminum-Induced Diamide Transfer from Group 6 Imido Diamido Complexes}, volume={23}, ISSN={0276-7333 1520-6041}, url={http://dx.doi.org/10.1021/om034322y}, DOI={10.1021/om034322y}, abstractNote={Reaction of AlMe3 with the imido compounds Mo(NPh)(o-(SiMe3N)2C6H4)(CH2)4 (1) and Mo(NPh)(o-(SiMe3N)2C6H4)L (2; L = diphenylacetylene) results in the transfer of the diamide ligand to the Al, giving the unusual arene complexes 3 and 4.}, number={5}, journal={Organometallics}, publisher={American Chemical Society (ACS)}, author={Ison, Elon A. and Abboud, Khalil A. and Ghiviriga, Ion and Boncella, James M.}, year={2004}, month={Mar}, pages={929–931} }
 @article{ison_cameron_abboud_boncella_2004, title={Synthesis, Structure, and Dynamics of Molybdenum Imido Alkyne Complexes}, volume={23}, ISSN={0276-7333 1520-6041}, url={http://dx.doi.org/10.1021/om049942t}, DOI={10.1021/om049942t}, abstractNote={The monomeric alkyne complexes (η2-alkyne)Mo(NPh)(o-(Me3SiN)2C6H4) (3) have been synthesized by the displacement of isobutylene from (η2-isobutylene)Mo(NPh)(o-(Me3SiN)2C6H4) (2). The alkyne fragment in these complexes is oriented perpendicular to the MoN bond of the cis imido ligand, as confirmed by an X-ray structural analysis of 3e. The deshielded nature of the chemical shifts of the α-carbons and terminal protons of the alkyne fragments in these complexes strongly suggests the participation of the alkyne π⊥ electrons in the Mo−alkyne interaction. The alkyne fragment in 3 rotates freely about the Mo−alkyne bond, resulting in the fluxional behavior of these complexes at room temperature. An activation barrier of 13.2 kcal/mol for the alkyne rotation was measured using VT NMR spectroscopy. Computational studies using a two-layer ONIOM model, and the B3LYP hybrid functional, provided insight into the Mo−alkyne bonding. The transition state for alkyne rotation has been calculated and is characterized by a p...}, number={17}, journal={Organometallics}, publisher={American Chemical Society (ACS)}, author={Ison, Elon A. and Cameron, Thomas M. and Abboud, Khalil A. and Boncella, James M.}, year={2004}, month={Aug}, pages={4070–4076} }