X-Ray Absorption Spectroscopic and Theoretical Studies on (L)2[Cu2(S2)n]2+ Complexes: Disulfide versus Disulfide(
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- 作者：Ritimukta Sarangi ; John T. York ; Matthew E. Helton ; Kiyoshi Fujisawa ; Kenneth D. Karlin ; William B. Tolman ; Keith O. Hodgson ; Britt Hedman ; Edward I. Solomon
- 刊名：Journal of the American Chemical Society
- 出版年：2008
- 出版时间：January 16, 2008
- 年：2008
- 卷：130
- 期：2
- 页码：676 - 686
- 全文大小：584K
- 年卷期：v.130,no.2(January 16, 2008)
- ISSN：1520-5126
文摘
Cu K-, Cu L-, and S K-edge X-ray absorption spectroscopic (XAS) data have been combinedwith density functional theory (DFT) calculations on [{(TMPA)Cu}2S2](ClO4)2 (1), [{Cu[HB(3,5-Pri2pz)3]}2(S2)] (2), and [{(TMEDA)Cu}2(S2)2](OTf)2 (3) to obtain a quantitative description of their ground statewavefunctions. The Cu L-edge intensities give 63 and 37% Cu d-character in the ground state of 1 and 2,respectively, whereas the S K-pre-edge intensities reflect 20 and 48% S character in their ground states,respetively. These data indicate a more than 2-fold increase in the total disulfide bonding character in 2relative to 1. The increase in the number of Cu-S bonds in 2 (
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2:2 S22- bridge) compared to 1((-1:1 S22- bridge) dominantly determines the large increase in covalency and Cu-disulfide bond strengthin 2. Cu K- and L- and S K-pre-edge energy positions directly demonstrate the CuII/(S2-)2 nature of 3. Thetwo disulfide(
1-)'s in 3 undergo strong bonding interactions that destabilize the resultant filled antibonding
* orbitals of the (S2-)2 fragment relative to the Cu 3d levels. This leads to an inverted bonding scheme in3 with dominantly ligand-based holes in its ground state, consistent with its description as a dicopper(II)-bis-disulfide(1-) complex.
-2:2 S22- bridge) compared to 1((-1:1 S22- bridge) dominantly determines the large increase in covalency and Cu-disulfide bond strengthin 2. Cu K- and L- and S K-pre-edge energy positions directly demonstrate the CuII/(S2-)2 nature of 3. Thetwo disulfide(1-)'s in 3 undergo strong bonding interactions that destabilize the resultant filled antibonding* orbitals of the (S2-)2 fragment relative to the Cu 3d levels. This leads to an inverted bonding scheme in3 with dominantly ligand-based holes in its ground state, consistent with its description as a dicopper(II)-bis-disulfide(1-) complex.