Low-Valent Cobalt Complexes with Three Different π Acceptor Ligands: Experimental and DFT Studies of the Reduced and the Low-Lying Excited States of (R-DAB)Co(NO)(CO), R-DAB = Substituted 1,4-Diaza-1,4-butadiene

Autor:	Monika Sieger, Wolfgang Kaim, Matthias Wanner, Theo L. Snoeck, D.J. Stufkens, Stanislav Záliš
Rok vydání:	2003
Předmět:	Ligand Chemistry Photochemistry Resonance (chemistry) Acceptor law.invention Inorganic Chemistry Crystallography law Excited state Density functional theory Molecular orbital Physical and Theoretical Chemistry Electron paramagnetic resonance Isopropyl
Zdroj:	Inorganic Chemistry. 42:3340-3346
ISSN:	1520-510X 0020-1669
Popis:	The complexes (RN=CH-CH=NR)Co(NO)(CO) with R = isopropyl, 2,6-diisopropylphenyl, or p-tolyl are chemically and electrochemically reducible to radical anions at potentials which strongly depend on R. The DFT calculated structure for the neutral compound with R = iPr agrees with the experiment, and the computed structure of the anion radical reveals changes according to a reduction of the R-DAB ligand. EPR results confirm an (R-DAB)-based singly occupied molecular orbital in [(RNCHCHNR)Co(NO)(CO)] . - , with minor but detectable contributions from NO as supported by IR spectroelectrochemistry and as quantified by DFT spin density calculations. The calculations indicate increasingly stabilized CO, NO, and RNCHCHNR π* acceptor orbitals, in that order. On the basis of TD-DFT (time-dependent density functional theory) calculations, the lowest-lying excited states are assigned to metal-to-(R-DAB) charge transfer transitions while bands due to the metal-to-nitrosyl charge transfer occur at higher energies but still in the visible region. Resonance Raman studies were used to probe these assignments.
Databáze:	OpenAIRE
Externí odkaz:	https://explore.openaire.eu/search/publication?articleId=doi_dedup___::e29c54e6a8367e50722568e63ad32f29 https://doi.org/10.1021/ic026078t Zobrazit plný text záznamu