@article{may_deegbey_edme_lee_perutz_jakubikova_dempsey_2024, title={Electronic Structure and Photophysics of Low Spin d5 Metallocenes}, volume={63}, ISSN={["1520-510X"]}, DOI={10.1021/acs.inorgchem.3c03451}, abstractNote={The electronic structure and photophysics of two low spin metallocenes, decamethylmanganocene (MnCp*2) and decamethylrhenocene (ReCp*2), were investigated to probe their promise as photoredox reagents. Computational studies support the assignment of 2E2 ground state configurations and low energy ligand-to-metal charge transfer transitions for both complexes. Weak emission is observed at room temperature for ReCp*2 with τ = 1.8 ns in pentane, whereas MnCp*2 is not emissive. Calculation of the excited state reduction potentials for both metallocenes reveal their potential potency as excited state reductants (E°′([MnCp*2]+/0*) = −3.38 V and E°′([ReCp*2]+/0*) = −2.61 V vs Fc+/0). Comparatively, both complexes exhibit mild potentials for photo-oxidative processes (E°′([MnCp*2]0*/–) = −0.18 V and E°′([ReCp*2]0*/–) = −0.20 V vs Fc+/0). These results showcase the rich electronic structure of low spin d5 metallocenes and their promise as excited state reductants.}, number={4}, journal={INORGANIC CHEMISTRY}, author={May, Ann Marie and Deegbey, Mawuli and Edme, Kedy and Lee, Katherine J. and Perutz, Robin N. and Jakubikova, Elena and Dempsey, Jillian L.}, year={2024}, month={Jan}, pages={1858–1866} }
@article{johnson_schwarz_deegbey_prakash_sharma_huang_ericsson_haggstrom_bendix_gupta_et al._2023, title={Ferrous and ferric complexes with cyclometalating N-heterocyclic carbene ligands: a case of dual emission revisited}, volume={8}, ISSN={["2041-6539"]}, DOI={10.1039/d3sc02806}, journal={CHEMICAL SCIENCE}, author={Johnson, Catherine Ellen and Schwarz, Jesper and Deegbey, Mawuli and Prakash, Om and Sharma, Kumkum and Huang, Ping and Ericsson, Tore and Haggstrom, Lennart and Bendix, Jesper and Gupta, Arvind Kumar and et al.}, year={2023}, month={Aug} }
@article{johnson_schwarz_deegbey_prakash_sharma_huang_ericsson_haggstrom_bendix_gupta_et al._2023, title={Ferrous and ferric complexes with cyclometalating N-heterocyclic carbene ligands: a case of dual emission revisited}, volume={14}, ISSN={["2041-6539"]}, DOI={10.1039/d3sc02806b}, abstractNote={Photoluminescence of the Fe III complex occurs only from its 2 LMCT state while its higher-energy but shorter-lived 2 MLCT state is non-luminescent. Blue emission arises instead from a photoproduct of the non-emitting Fe II complex.}, number={37}, journal={CHEMICAL SCIENCE}, author={Johnson, Catherine Ellen and Schwarz, Jesper and Deegbey, Mawuli and Prakash, Om and Sharma, Kumkum and Huang, Ping and Ericsson, Tore and Haggstrom, Lennart and Bendix, Jesper and Gupta, Arvind Kumar and et al.}, year={2023}, month={Sep}, pages={10129–10139} }
@article{rodriguez_deegbey_chen_jakubikova_dempsey_2023, title={Isocyanide Ligands Promote Ligand-to-Metal Charge Transfer Excited States in a Rhenium(II) Complex}, volume={1}, ISSN={["1520-510X"]}, DOI={10.1021/acs.inorgchem.2c03193}, abstractNote={A metal-to-ligand charge transfer with mixed intraligand character is observed for the rhenium hexakisarylisocyanide complex [Re(CNAr)6]PF6 (CNAr = 2,6-dimethylphenylisocyanide, λmax = 300 nm). Upon oxidation to [Re(CNAr)6](PF6)2, the dominant low energy optical transition is a ligand-to-metal charge transfer (LMCT) mixed with intraligand transitions (λmax = 650 nm). TD-DFT was used to identify the participating ligand-based orbitals in the LMCT transition, revealing that the majority of the donor orbital is based on the aryl ring (85%) as opposed to the CN bond (14%). For both [Re(CNAr)6]+ and [Re(CNAr)6]2+, structural characterization by X-ray diffraction reveals deviations from Oh geometry at the central Re ion, with larger reduction in symmetry observed for Re(II). For [Re(CNAr)6]+, these structural changes lead to a broadening of the strong ν(C≡N) stretch (2065 cm-1), as the degeneracy of the T1u IR-active mode is broken. Furthermore, a shoulder is observed for this ν(C≡N) stretch, resulting from deviation of the C-N-Ar bond from linearity. By contrast, [Re(CNAr)6]2+ has two weak bands in the ν(C≡N) region (2065 and 2121 cm-1). DFT calculations indicate that reduction of symmetry at the central rhenium ion manifests in the decrease in intensity and the observed split of the ν(C≡N) band. Stability of both complexes are limited by light-induced decomposition where Re(I) dissociates a isocyanide ligand upon irradiation and Re(II) absorbance decays under ambient light. These data provide new insights to the electronic structure of [Re(CNAr)6]2+, enhancing our understanding of LMCT excited states and the versatility of isocyanide ligands.}, journal={INORGANIC CHEMISTRY}, author={Rodriguez, Tayliz M. and Deegbey, Mawuli and Chen, Chun-Hsing and Jakubikova, Elena and Dempsey, Jillian L.}, year={2023}, month={Jan} }
@article{johnsen_deegbey_grills_polyansky_goldberg_jakubikova_mallouk_2023, title={Lewis Acids and Electron-Withdrawing Ligands Accelerate CO Coordination to Dinuclear Cu-I Compounds}, volume={62}, ISSN={["1520-510X"]}, DOI={10.1021/acs.inorgchem.3c01003}, abstractNote={A series of dinuclear molecular copper complexes were prepared and used to model the binding and Lewis acid stabilization of CO in heterogeneous copper CO2 reduction electrocatalysts. Experimental studies (including measurement of rate and equilibrium constants) and electronic structure calculations suggest that the key kinetic barrier for CO binding may be a σ-interaction between CuI and the incoming CO ligand. The rate of CO coordination can be increased upon the addition of Lewis acids or electron-withdrawing substituents on the ligand backbone. Conversely, Keq for CO coordination can be increased by adding electron density to the metal centers of the compound, consistent with stronger π-backbonding. Finally, the electrochemically measured kinetic results were mapped onto an electrochemical zone diagram to illustrate how these system changes enabled access to each zone.}, number={23}, journal={INORGANIC CHEMISTRY}, author={Johnsen, Walter D. and Deegbey, Mawuli and Grills, David C. and Polyansky, Dmitry E. and Goldberg, Karen I. and Jakubikova, Elena and Mallouk, Thomas E.}, year={2023}, month={May}, pages={9146–9157} }
@article{lee_son_deegbey_woodhouse_hart_beissel_cesana_jakubikova_mccusker_schlau-cohen_2023, title={Observation of parallel intersystem crossing and charge transfer-state dynamics in [Fe(bpy)3]2+ from ultrafast 2D electronic spectroscopy}, volume={14}, ISSN={["2041-6539"]}, DOI={10.1039/d3sc02613b}, abstractNote={Transition metal-based charge-transfer complexes represent a broad class of inorganic compounds with diverse photochemical applications. Charge-transfer complexes based on earth-abundant elements have been of increasing interest, particularly the canonical [Fe(bpy)3]2+. Photoexcitation into the singlet metal-ligand charge transfer (1MLCT) state is followed by relaxation first to the ligand-field manifold and then to the ground state. While these dynamics have been well-studied, processes within the MLCT manifold that facilitate and/or compete with relaxation have been more elusive. We applied ultrafast two-dimensional electronic spectroscopy (2DES) to disentangle the dynamics immediately following MLCT excitation of this compound. First, dynamics ascribed to relaxation out of the initially formed 1MLCT state was found to correlate with the inertial response time of the solvent. Second, the additional dimension of the 2D spectra revealed a peak consistent with a ∼20 fs 1MLCT → 3MLCT intersystem crossing process. These two observations indicate that the complex simultaneously undergoes intersystem crossing and direct conversion to ligand-field state(s). Resolution of these parallel pathways in this prototypical earth-abundant complex highlights the ability of 2DES to deconvolve the otherwise obscured excited-state dynamics of charge-transfer complexes.}, number={45}, journal={CHEMICAL SCIENCE}, author={Lee, Angela and Son, Minjung and Deegbey, Mawuli and Woodhouse, Matthew D. and Hart, Stephanie M. and Beissel, Hayden F. and Cesana, Paul T. and Jakubikova, Elena and McCusker, James K. and Schlau-Cohen, Gabriela S.}, year={2023}, month={Nov}, pages={13140–13150} }
@article{rodriguez_deegbey_jakubikova_dempsey_2021, title={The ligand-to-metal charge transfer excited state of [Re(dmpe)(3)](2+)}, volume={7}, ISSN={["1573-5079"]}, DOI={10.1007/s11120-021-00859-7}, journal={PHOTOSYNTHESIS RESEARCH}, author={Rodriguez, Tayliz M. and Deegbey, Mawuli and Jakubikova, Elena and Dempsey, Jillian L.}, year={2021}, month={Jul} }