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• 作者：Chien-Ming Lee ; Ya-Lan Chuang ; Chao-Yi Chiang ; Gene-Hsiang Lee ; Wen-Feng Liaw
• 刊名：Inorganic Chemistry
• 出版年：2006
• 出版时间：December 25, 2006
• 年：2006
• 卷：45
• 期：26
• 页码：10895 - 10904
• 全文大小：316K
• 年卷期：v.45,no.26(December 25, 2006)
• ISSN：1520-510X

文摘

The stable mononuclear Ni(III)-thiolate complexes [Ni^III(L)(P(C₆H₃-3-SiMe₃-2-S)₃)]^- (L = SePh (2), Cl (3), SEt (4),2-S-C₄H₃S (5), CH₂CN (7)) were isolated and characterized by UV-vis, EPR, IR, SQUID, CV, ¹H NMR, and single-crystal X-ray diffraction. The increased basicity (electronic density) of the nickel center of complexes [Ni^III(L)(P(C₆H₃-3-SiMe₃-2-S)₃)]^- modulated by the monodentate ligand L and the substituted groups of the phenylthiolaterings promotes the stability and reactivity. In contrast to the irreversible reduction at -1.17 V (vs Cp₂Fe/Cp₂Fe⁺) forcomplex 3, the cyclic voltammograms of complexes [Ni^III(SePh)(P(o-C₆H₄S)₃)]^-, 2, 4, and 7 display reversible Ni^III/IIredox processes with E_1/2 = -1.20, -1.26, -1.32, and -1.34 V (vs Cp₂Fe/Cp₂Fe⁺), respectively. Compared tocomplex 2 containing a phenylselenolate-coordinated ligand, complex 4 with a stronger electron-donating ethylthiolatecoordinated to the Ni(III) promotes dechlorination of CH₂Cl₂ to yield complex 3 (k_obs = (6.01 ± 0.03) × 10^-4 s^-1for conversion of complex 4 into 3 vs k_obs = (4.78 ± 0.02) × 10^-5 s^-1 for conversion of complex 2 into 3).Interestingly, addition of CH₃CN into complex 3 in the presence of sodium hydride yielded the stable Ni(III)-cyanomethanide complex 7 with a Ni^III-CH₂CN bond distance of 2.037(3) Å. The Ni^III-SEt bond length of 2.273(1)Å in complex 4 is at the upper end of the 2.12-2.28 Å range for the Ni^III-S bond lengths of the oxidized-form[NiFe] hydrogenases. In contrast to the inertness of complexes 3 and 7 under CO atmosphere, carbon monoxidetriggers the reductive elimination of the monodentate chalcogenolate ligand of complexes 2, 4, and 5 to producethe trigonal bipyramidal complex [Ni^II(CO)(P(C₆H₃-3-SiMe₃-2-S)₃)]^- (6).