Spectroscopic and DFT investigation of [M{HB(3,5-iPr 2pz)3}(SC6F5)] (M = Mn, Fe, Co, Ni, Cu, and Zn) model complexes: Periodic trends in metal-thiolate bonding

Serge I. Gorelsky, Lipika Basumallick, Josh Vura-Weis, Ritimukta Sarangi, Keith O. Hodgson, Britt Hedman, Kiyoshi Fujisawa, Edward I. Solomon

Research output: Contribution to journalArticlepeer-review

Abstract

A series of metal-varied [ML(SC6F5)] model complexes (where L = hydrotris(3,5-diisopropyl-1-pyrazolyl)borate and M = Mn, Fe, Co, Ni, Cu, and Zn) related to blue copper proteins has been studied by a combination of absorption, MCD, resonance Raman, and S K-edge X-ray absorption spectroscopies. Density functional calculations have been used to characterize these complexes and calculate their spectra. The observed variations in geometry, spectra, and bond energies are interpreted in terms of changes in the nature of metal-ligand bonding interactions. The metal 3d-ligand orbital interaction, which contributes to covalent bonding in these complexes, becomes stronger going from Mn(II) to Co(II) (the σ contribution) and to Cu(II) (the π contribution). This change in the covalency results from the increased effective nuclear charge of the metal atom in going from Mn(II) to Zn(II) and the change in the 3d orbital populations (d5→d10). Ionic bonding also plays an important role in determining the overall strength of the ML+-SC 6F5- interaction. However, there is a compensating effect: as the covalent contribution to the metal-ligand bonding increases, the ionic contribution decreases. These results provide insight into the Irving-Williams series, where it is found that the bonding of the ligand being replaced by the thiolate makes a major contribution to the observed order of the stability constants over the series of metal ions.

Original languageEnglish (US)
Pages (from-to)4947-4960
Number of pages14
JournalInorganic Chemistry
Volume44
Issue number14
DOIs
StatePublished - Jul 11 2005
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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