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Excitation-Wavelength-Dependent Photophysics of d⁸d⁸ Di-isocyanide Complexes

Pižl, Martin and Hunter, Bryan M. and Sazanovich, Igor V. and Towrie, Michael and Gray, Harry B. and Záliš, Stanislav and Vlček, Antonín (2022) Excitation-Wavelength-Dependent Photophysics of d⁸d⁸ Di-isocyanide Complexes. Inorganic Chemistry, 61 (6). pp. 2745-2759. ISSN 0020-1669. doi:10.1021/acs.inorgchem.1c02645.

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Binuclear Rh(I) and Ir(I) TMB (2,5-dimethyl-2,5-diisocyanohexane) and dimen (1,8-diisocyanomenthane) complexes possess dσ*pσ and dπpσ singlet and triplet excited states that can be selectively excited in the visible and UV spectral regions. Using perturbational spin–orbit TDDFT, we unraveled the detailed character and spin mixing of these electronic transitions and found that delocalization of pσ and dπ orbitals over C≡N– groups makes C≡N stretching vibrations sensitive reporters of electron density and structural changes upon electronic excitation. Picosecond time-resolved infrared spectra measured after visible light, 375 nm, and 316 nm excitation revealed excitation-wavelength-dependent deactivation cascades. Visible light irradiation prepares the ¹dσ*pσ state that, after one or two (sub)picosecond relaxation steps, undergoes 70–1300 ps intersystem crossing to ³dσ*pσ, which is faster for the more flexible dimen complexes. UV-excited ^(1,3)dπpσ states decay with (sub)picosecond kinetics through a manifold of high-lying triplet and mixed-spin states to ³dσ*pσ with lifetimes in the range of 6–19 ps (316 nm) and 19–43 ps (375 nm, Ir only), bypassing ¹dσ*pσ. Most excited-state conversion and some relaxation steps are accompanied by direct decay to the ground state that is especially pronounced for the most flexible long/eclipsed Rh(dimen) conformer.

Item Type:Article
Related URLs:
URLURL TypeDescription
Pižl, Martin0000-0003-4990-9218
Hunter, Bryan M.0000-0001-8559-9304
Sazanovich, Igor V.0000-0002-8000-7645
Towrie, Michael0000-0002-1305-701X
Gray, Harry B.0000-0002-7937-7876
Záliš, Stanislav0000-0003-4345-3205
Vlček, Antonín0000-0002-6413-8311
Alternate Title:Excitation-Wavelength-Dependent Photophysics of d8d8 Di-isocyanide Complexes
Additional Information:© 2021 American Chemical Society. Received: August 26, 2021; Published: December 14, 2021. This research was supported by the Czech Science Foundation (GAČR) grant no. 21-05180S, the Czech Ministry of Education (MŠMT) grant no. LTAUSA18026, EPSRC (UK) grant no. EP/R029687/1, the STFC Rutherford Appleton Laboratory (UK), the United States National Science Foundation (CHE-1763429), and the Arnold and Mabel Beckman Foundation. The authors declare no competing financial interest.
Funding AgencyGrant Number
Czech Science Foundation (GAČR)21-05180S
Ministry of Education (Czech Republic)LTAUSA18026
Engineering and Physical Sciences Research Council (EPSRC)EP/R029687/1
Science and Technology Facilities Council (STFC)UNSPECIFIED
Arnold and Mabel Beckman FoundationUNSPECIFIED
Subject Keywords:Oscillation, Molecular structure, Quantum mechanics, Transition metals, Kinetics
Issue or Number:6
Record Number:CaltechAUTHORS:20211220-955752000
Persistent URL:
Official Citation:Excitation-Wavelength-Dependent Photophysics of d8d8 Di-isocyanide Complexes. Martin Pižl, Bryan M. Hunter, Igor V. Sazanovich, Michael Towrie, Harry B. Gray, Stanislav Záliš, and Antonín Vlček. Inorganic Chemistry 2022 61 (6), 2745-2759; DOI: 10.1021/acs.inorgchem.1c02645
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112590
Deposited By: George Porter
Deposited On:21 Dec 2021 15:45
Last Modified:02 Mar 2022 18:14

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