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Title: Sulfur K-Edge X-Ray Absorption Spectroscopy As a Probe of Ligand-Metal Bond Covalency: Metal Vs Ligand Oxidation in Copper And Nickel Dithiolene Complexes

Abstract

No abstract prepared.

Authors:
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
Stanford Linear Accelerator Center (SLAC)
Sponsoring Org.:
USDOE
OSTI Identifier:
901579
Report Number(s):
SLAC-REPRINT-2007-017
Journal ID: ISSN 0002-7863; JACSAT; TRN: US200715%%166
DOE Contract Number:
AC02-76SF00515
Resource Type:
Journal Article
Resource Relation:
Journal Name: J.Am.Chem.Soc.129:2316,2007; Journal Volume: 129
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ABSORPTION SPECTROSCOPY; CHEMICAL BONDS; COPPER; COPPER COMPLEXES; COVALENCE; NICKEL; NICKEL COMPLEXES; ORGANIC SULFUR COMPOUNDS; OXIDATION; PROBES; SULFUR; X-RAY SPECTROSCOPY; Other,OTHER

Citation Formats

Sarangi, R., /Stanford U., Chem. Dept., George, S.D., /SLAC, SSRL, Rudd, D.J., Szilagyi, R.K., /Stanford U., Chem. Dept., Ribas, X., Rovira, C., /Barcelona, Autonoma U., Almeida, M., /ITN, Sacavem, Hodgson, K.O., /SLAC, SSRL /Stanford U., Chem. Dept., Hedman, B., /SLAC, SSRL, and Solomon, E.I. Sulfur K-Edge X-Ray Absorption Spectroscopy As a Probe of Ligand-Metal Bond Covalency: Metal Vs Ligand Oxidation in Copper And Nickel Dithiolene Complexes. United States: N. p., 2007. Web. doi:10.1021/ja0665949.
Sarangi, R., /Stanford U., Chem. Dept., George, S.D., /SLAC, SSRL, Rudd, D.J., Szilagyi, R.K., /Stanford U., Chem. Dept., Ribas, X., Rovira, C., /Barcelona, Autonoma U., Almeida, M., /ITN, Sacavem, Hodgson, K.O., /SLAC, SSRL /Stanford U., Chem. Dept., Hedman, B., /SLAC, SSRL, & Solomon, E.I. Sulfur K-Edge X-Ray Absorption Spectroscopy As a Probe of Ligand-Metal Bond Covalency: Metal Vs Ligand Oxidation in Copper And Nickel Dithiolene Complexes. United States. doi:10.1021/ja0665949.
Sarangi, R., /Stanford U., Chem. Dept., George, S.D., /SLAC, SSRL, Rudd, D.J., Szilagyi, R.K., /Stanford U., Chem. Dept., Ribas, X., Rovira, C., /Barcelona, Autonoma U., Almeida, M., /ITN, Sacavem, Hodgson, K.O., /SLAC, SSRL /Stanford U., Chem. Dept., Hedman, B., /SLAC, SSRL, and Solomon, E.I. Wed . "Sulfur K-Edge X-Ray Absorption Spectroscopy As a Probe of Ligand-Metal Bond Covalency: Metal Vs Ligand Oxidation in Copper And Nickel Dithiolene Complexes". United States. doi:10.1021/ja0665949.
@article{osti_901579,
title = {Sulfur K-Edge X-Ray Absorption Spectroscopy As a Probe of Ligand-Metal Bond Covalency: Metal Vs Ligand Oxidation in Copper And Nickel Dithiolene Complexes},
author = {Sarangi, R. and /Stanford U., Chem. Dept. and George, S.D. and /SLAC, SSRL and Rudd, D.J. and Szilagyi, R.K. and /Stanford U., Chem. Dept. and Ribas, X. and Rovira, C. and /Barcelona, Autonoma U. and Almeida, M. and /ITN, Sacavem and Hodgson, K.O. and /SLAC, SSRL /Stanford U., Chem. Dept. and Hedman, B. and /SLAC, SSRL and Solomon, E.I.},
abstractNote = {No abstract prepared.},
doi = {10.1021/ja0665949},
journal = {J.Am.Chem.Soc.129:2316,2007},
number = ,
volume = 129,
place = {United States},
year = {Wed Mar 28 00:00:00 EDT 2007},
month = {Wed Mar 28 00:00:00 EDT 2007}
}
  • X-ray absorption spectra (XAS) have been measured at the chloride K-edge for a series of complexes containing chloride ligands bound to open shell d{sup 9} copper ions in order to probe ligand-metal bonding. The intensity of the pre-edge feature in these spectra reflects the covalency in the half-occupied d{sub x}{sup 2-}{sub y}{sup 2-} derived molecular orbital (HOMO) of the complex. The energy of the pre-edge feature as well as the energy of the rising absorption edge provides quantitative information about the covalency of the ligand-metal interaction, the charge donated by the chloride, and the energy of the copper d-manifold. Themore » results demonstrate that ligand K-edge XAS features can be used to obtain information about ligand-metal bonding. The results also identify the chemical basis for trends in the XAS data for the following complexes: D{sub 4h} CuCl{sub 4}{sup 2-}, D{sub 2d} CuCl{sub 4}{sup 2-}, planar trans-CuCl{sub 2-} (pdmp){sub 2} (pdmp = N-phenyl-3,5-dimethylpyrazole), square pyramidal CuCl{sub 5}{sup 3-}, the planar dimer KCuCl{sub 3}, the distorted tetrahedral dimer (Ph{sub 4}P)CuCl{sub 3}, and two dimers with mixed ligation, one containing a bridging chloride, and the other, containing terminally bound chloride. Several of these results are supported by independent spectral data or by basic ligand field concepts. A geometric distortion from square planar to distorted tetrahedral results in a decrease in the chloride-copper HOMO covalency but an increase in the total charge donation by the chlorides. While the geometry can maximize the overlap for a highly covalent HOMO, this does not necessarily reflect the overall charge donation.« less
  • No abstract prepared.
  • Ligand K-edge X-ray absorption spectroscopy has been shown to be a powerful tool in the study of the electronic structure of ligand-metal interactions in open shell metal ions. The technique was developed previously for application to ligand-Cu[sup II] covalency but has now been extended for application to metal ions with more than one electron (or hole). By use of the expressions derived and the protocol outlined in this study, ligand pre-edge intensity provides a direct probe of the ligand valence p-orbital covalency of a metal-ligand bond. The technique is extended to other d[sup n] systems by application of the analysismore » presented in this paper. 40 refs., 6 figs., 9 tabs.« less
  • X-ray absorption spectra have been measured at the S K-, Cl K-, and Mo L{sub 3}- and L{sub 2}-edges for the d{sup 0} dioxomolybdenum(VI) complexes LMoO{sub 2}(SCH{sub 2}Ph), LMoO{sub 2}Cl, and LMoO{sub 2}(OPh) (L = hydrotris(3,5-dimethyl-1-pyrazolyl)borate) to investigate ligand-metal covalency and its effects on oxo transfer reactivity. Two dominant peaks are observed at the S K-edge (2,470.5 and 2,472.5 eV) for LMoO{sub 2}(SCH{sub 2}Ph) and at the Cl K-edge (2,821.9 and 2,824.2 eV) for LMoO{sub 2}Cl, demonstrating two major covalent contributions from S and Cl to the Mo d orbitals.Density functional calculations were performed on models of the three Momore » complexes, and the energies and characters of the Mo 4d orbitals were interpreted in terms of the effects of two strong cis-oxo bonds and additional perturbations due to the thiolate, chloride, or alkoxide ligand. The major perturbation effects are for thiolate and Cl{sup {minus}} {pi} mixed with the d{sub xz} orbital and {sigma} mixed with the d{sub z}{sup 2} orbital. The calculated 4d orbital energy splittings for models of these two major contributions to the bonding of thiolate and Cl ligands (2.47 and 2.71 eV, respectively) correspond to the splittings observed experimentally for the two dominant ligand K-edge peaks for LMoO{sub 2}(SCH{sub 2}Ph) and LMoO{sub 2}Cl (2.0 and 2.3 eV, respectively) after consideration of final state electronic relaxation. Quantification of the S and Cl covalencies in the d orbital manifold from the pre-edge intensity yields, {approximately} 42% and {approximately} 17% for LMoO{sub 2}(SCH{sub 2}Ph) and LMoO{sub 2}Cl, respectively. The Mo L{sub 2}-edge spectra provide a direct probe of metal 4 d character for the three Mo complexes. The spectra contain a strong, broad peak and two additional sharp peaks at higher energy, which are assigned to 2p transitions to the overlapping t{sub 2g} set and to the d{sub z}{sup 2} and d{sub xy} levels, respectively. The total peak intensities of the Mo L{sub 2}-edges for LMoO{sub 2}(OPh) and LMoO{sub 2}Cl are similar to and larger than those for LMoO{sub 2}(SCH{sub 2}Ph), which agrees with the calculated trend in ligand-metal covalency. The theoretical and experimental description of bonding developed from these studies provides insight into the relationship of electronic structure to the oxo transfer chemistry observed for the LMoO{sub 2}X complexes. These results imply that anisotropic covalency of the Mo-S{sub cys} bond in sulfite oxidase may promote preferential transfer of one of the oxo groups during catalysis.« less