American Chemical Society
ic700719h_si_016.cif (28.22 kB)

Mononuclear Ni(II)-Thiolate Complexes with Pendant Thiol and Dinuclear Ni(III/II)-Thiolate Complexes with Ni···Ni Interaction Regulated by the Oxidation Levels of Nickels and the Coordinated Ligands

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posted on 2007-10-15, 00:00 authored by Chien-Ming Lee, Tzung-Wen Chiou, Hsin-Hung Chen, Chao-Yi Chiang, Ting-Shen Kuo, Wen-Feng Liaw
Compared to [NiII(SePh)(P(o-C6H3-3-SiMe3-2-S)2(o-C6H3-3-SiMe3-2-SH))] (1a) and [NiII(Cl)(P(o-C6H3-3-SiMe3-2-S)2(o-C6H3-3-SiMe3-2-SH))] (3a) with a combination of the intramolecular [Ni···HS] and [Ni−S···H−S] interactions, complexes [NiII(SePh)(P(o-C6H3-3-SiMe3-2-S)2(o-C6H3-3-SiMe3-2-SH))] (1b) and [NiII(Cl)(P (o-C6H3-3-SiMe3-2-S)2(o-C6H3-3-SiMe3-2-SH))] (3b) with intramolecular [Ni···H−S] interaction exhibit lower νS-H stretching frequencies (2137 and 2235 cm-1 for 1b and 3b vs 2250 and 2287 cm-1 for 1a and 3a, respectively) and smaller torsion angles (27.2° for 3b vs 58.9 and 59.1° for 1a and 3a, respectively). The pendant thiol interaction modes of 1a, 3a, and 3b in the solid state are controlled by the solvent pairs of crystallization. Oxygen oxidation of dinuclear [NiII(P(o-C6H3-3-SiMe3-2-S)2(o-C6H3-3-SiMe3-2-SH))]2 (4) yielded thermally stable dinuclear [NiIII(P(o-C6H3-3-SiMe3-2-S)2(o-C6H3-3-SiMe3-2-μ-S))]2 (5). The two paramagnetic d7 NiIII cores (S = 1/2) with antiferromagnetic coupling (J = −3.13 cm-1) rationalize the diamagnetic property of 5. The fully delocalized mixed-valence [Ni(II)−Ni(III)] complexes [Ni2(P(o-C6H3-3-SiMe3-2-S)3)2] (6) and [Ni2(P(o-C6H3-3-SiMe3-2-S)3)(P(o-C6H3-3-SiMe3-2-S)2(o-C6H3-3-SiMe3-2-SCH3))] (7) were isolated upon the reduction of 5 and the methylation of 6, respectively. The electronic perturbation from the sulfur methylation of 6 triggers the stronger Ni···Ni interaction and the geometrical rearrangement from the diamond shape of the [NiS2Ni] core to the butterfly structure of [Ni(μ-S)2Ni] to yield 7 with Ni···Ni distances of 2.6088(1) Å. The distinctly different Ni···Ni distances (2.6026(7) for 5 and 2.8289(15) Å for 6) and the coordination number of the nickels indicate a balance of geometrical requirements for different oxidation levels of [PS3Ni−NiPS3] cores of 5 and 6.