Diplatinum-Center-Mediated Transformation of a Substituted Benzene to a Cyclohexadienyl Dianion and the Breaking of C−Cl Bonds: Syntheses and Structures of Pt2R4(ttab) and Pt2(CH3)4(ttab)Cl2

Abstract

Two novel dinuclear platinum(II) complexes, Pt2(CH3)4(ttab), 1, and Pt2Ph4(ttab), 2, have been synthesized from the reaction of 1,2,4,5-tetrakis(1-N-7-azaindolyl)benzene (ttab) with Pt2(CH3)4(SMe2)2 and [PtPh2(SMe2)]n (n = 2, 3), respectively. The Pt(II) centers in both complexes are within van der Waals contact distances with the central benzene ring of the ttab ligand. Compound 1 was found to react readily with saturated chlorinated molecules such as CFCl3, CCl4, CHCl3, and CH2Cl2 at ambient temperature to yield a dinuclear platinum(IV) complex, Pt2(CH3)4(ttab)Cl2, 3, quantitatively. The central benzene ring of the ttab ligand in 1 was transformed to a 1,4-cyclohexadiene dianion in 3, accompanied by the formation of two internal Pt−C bonds. The structures of 1, 2, and 3 are determined by X-ray diffraction analyses.