N2S2Ni Metallodithiolate Complexes as Ligands: Structural and Aqueous Solution Quantitative Studies of the Ability of Metal Ions to Form M-S-Ni Bridges to Mercapto Groups Coordin
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- 作者：Melissa L. Golden ; Curtis M. Whaley ; Marilyn V. Rampersad ; Joseph H. Reibenspies ; Robert D. Hancock ; and Marcetta Y. Darensbourg
- 刊名：Inorganic Chemistry
- 出版年：2005
- 出版时间：February 21, 2005
- 年：2005
- 卷：44
- 期：4
- 页码：875 - 883
- 全文大小：330K
- 年卷期：v.44,no.4(February 21, 2005)
- ISSN：1520-510X
文摘
The nickel(II) complex of an N2S2 ligand, derived from a diazacycle, N,N'-bis(mercaptoethyl)-1,5-diazacycloheptane,(bme-dach)Ni, Ni-1', serves as a metallodithiolate ligand to NiII, CuI, ZnII, AgI, and PbII. The binding ability of theNiN2S2 ligand to the metal ions was established through spectrochemical titrations in aqueous media and comparedto classical S-donor ligands. For M = Ni, Zn, Pb, binding constants, log K = ca. 2, were computed for 1:1Ni-1'/M(solvate) adducts; for Ag+ and Cu+, the 3:2 (Ni-1')3M2 adducts were the first formed products even in waterwith log 
3,2 values of 26 and >30, respectively. In all cases, the binding ability of Ni-S-R is intermediate betweenthat of a free thiolate and a free thioether. The great specificity for copper over nickel and zinc by N2S2Ni, whichserves as a reasonable structural model for the distal nickel of the acetyl CoA synthase active site, relates tobiochemical studies of heterogeneity (metal content and type) in various preparations of acetyl CoA synthaseenzyme.
3,2 values of 26 and >30, respectively. In all cases, the binding ability of Ni-S-R is intermediate betweenthat of a free thiolate and a free thioether. The great specificity for copper over nickel and zinc by N2S2Ni, whichserves as a reasonable structural model for the distal nickel of the acetyl CoA synthase active site, relates tobiochemical studies of heterogeneity (metal content and type) in various preparations of acetyl CoA synthaseenzyme.