Inorganic Chemistry, Vol.46, No.21, 8913-8923, 2007
Mononuclear Ni(II)-Thiolate complexes with pendant thiol and dinudear Ni(III/II)-Thiolate complexes with Ni center dot center dot center dot Ni interaction regulated by the oxidation levels of nickels and the coordinated ligands
Compared to [Ni-II(SePh)(P(o-C6H3-3-SiMe3-2-S)(2)(o-C6H3-3-SiMe3-2-SH))](-) (1a) and [Ni-II(Cl)(P(o-C6H3-3-SiMe3-2-S)(2)(o-C6H3-3-SiMe3-2-SH))](-) (3a) with a combination of the intramolecular [Ni center dot center dot center dot H-S] and [Ni-S center dot center dot center dot H-S] interactions, complexes (Ni-II(SePh)(P(o-C6H3-3-Sime(3)-2-S)(2)(o-C6H3-3-SiMe3-2-SH))](-) (1b) and [Ni-II(Cl)(P (o-C6H3-3-SiMe3-2-S)(2)(o-C6H3-3-SiMe3-2-SH))](-) (3b) with intramolecular [Ni center dot center dot center dot H-S] interaction exhibit lower nu(S-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 (27.20 for 3b vs 58.9 and 59.1 degrees 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 [Ni-II(P(o-C6H3-3-SiMe3-2-S)(2)(o-C6H3-3-SiMe3-2-SH))](2) (4) yielded thermally stable dinuclear [Ni-III(P(o-C6H3-3-SiMe3-2S)(2)(o-C6H3-3-SiMe3-2-mu-S))](2) (5). The two paramagnetic d(7) Ni-II 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 [Ni-2(P(o-C6H3-3-SiMe3-2-S)(3))(2)](-) (6) and [Ni-2(P(o-C6H3-3-SiMe3-2-S)(3))(P(o-C6H3-3-SiMe3-2-S)(2)(o-C6H3-3-siMe(3 )-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 center dot center dot center dot Ni interaction and the geometrical rearrangement from the diamond shape of the [NiS2Ni] core to the butterfly structure of [Ni(mu-S)(2)Ni] to yield 7 with Ni center dot center dot center dot Ni distances of 2.6088(1) angstrom. The distinctly different Ni center dot center dot center dot Ni distances (2.6026(7) for 5 and 2.8289(15) angstrom 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.