X-ray absorption spectroscopic and computational investigation of a possible S⋯S interaction in the [Cu 3S 2] 3+ core

Ritimukta Sarangi, Lei Yang, Stuart G. Winikoff, Laura Gagliardi, Christopher J. Cramer, William B. Tolman, Edward I. Solomon

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28 Scopus citations

Abstract

The electronic structure of the [Cu 3S 2] 3+ core of [(LCu) 3(S) 2] 3+ (L = N,N,N′,N′-tetramethyl-2R,3R-cyclohexanediamine) is investigated using a combination of Cu and S K-edge X-ray absorption spectroscopy and calculations at the density functional and multireference second-order perturbation levels of theory. The results show that the [Cu 3S 2] 3+ core is best described as having all copper centers close to but more oxidized than Cu 2+, while the charge on the S 2 fragment is between that of a sulfide (S 2-) and a subsulfide (S 2 3-) species. The [Cu 3S 2] 3+ core thus is different from a previously described, analogous [Cu 3O 2] 3+ core, which has a localized [(Cu 3+Cu 2+Cu 2+)(O 2-) 2] 3+ electronic structure. The difference in electronic structure between the two analogues is attributed to increased covalent overlap between the Cu 3d and S 3p orbitals and the increased radial distribution function of the S 3p orbital (relative to O 2p). These features result in donation of electron density from the S-S θ* to the Cu and result in some bonding interaction between the two S atoms at ∼2.69 Å in [Cu 3S 2] 3+, stabilizing a delocalized S = 1 ground state.

Original languageEnglish (US)
Pages (from-to)17180-17191
Number of pages12
JournalJournal of the American Chemical Society
Volume133
Issue number43
DOIs
StatePublished - Nov 2 2011

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