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A Spectroscopic and Computationally Minimal Approach to the Analysis of Charge‐Transfer Processes in Conformationally Fluxional Mixed‐Valence and Heterobimetallic Complexes
Author(s) -
Gückel Simon,
Gluyas Josef B. G.,
Eaves Samantha G.,
Safari Parvin,
Yufit Dmitry S.,
Sobolev Alexandre N.,
Kaupp Martin,
Low Paul J.
Publication year - 2019
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201901200
Subject(s) - chemistry , conformational isomerism , time dependent density functional theory , valence (chemistry) , molecular physics , computational chemistry , bimetallic strip , charge (physics) , ground state , ab initio , density functional theory , crystallography , molecule , atomic physics , physics , quantum mechanics , organic chemistry , metal
Class II mixed‐valence bimetallic complexes {[Cp′(PP)M]C≡C−C≡N[M′(PP)′Cp′]} 2+ (M, M′=Ru, Fe; PP=dppe, (PPh 3 ) 2 ; Cp′=Cp*, Cp) exist as conformational ensembles in fluid solution, with a population of structures ranging from cis ‐ to trans ‐like geometries. Each conformer gives rise to its own series of low‐energy intervalence charge‐transfer (IVCT) and local d–d transitions, which overlap in the NIR region, giving complex band envelopes in the NIR absorption spectrum, which prevent any meaningful attempt at analysis of the band shape. However, DFT and time‐dependent (TD)DFT calculations with dispersion‐corrected global‐hybrid (BLYP35‐D3) or local hybrid (lh‐SsirPW92‐D3) functionals on a small number of optimised structures chosen to sample the ground state potential energy hypersurfaces of each of these complexes has proven sufficient to explain the major features of the electronic spectra. Although modest in terms of computational expense, this approach provides a more accurate description of the underlying molecular electronic structure than would be possible through analysis of the IVCT band by using the static point‐charge model of Marcus–Hush theory and derivatives, or TDDFT calculations from a single (global) minimum energy geometry.