Syntheses and characterization of heterobimetallic complexes (dppf)Pt(dithiolate) (dppf: bis(diphenylphosphino)ferrocene); X-ray crystal structures of (dppf)PtL where L = dmit, phdt and i-mnt

Hetrobimetallic complexes of the type (dppf)PtL (dppf = 1,1′-bis(diphenylphosphino)ferrocene; L = dmit (1,3-dithiole-2-thione-4,5-dithiolate), dddt (5,6-dihydro-1,4-dithiin-2,3-dithiolate), phdt (6-hydro-5-phenyl-1,4-dithiin-2,3-dithiolate), dphdt (5,6-diphenyl-1,4-dithiin-2,3-dithiolate), mtdt (1,2-bis(methylthio)ethylene-1,2-dithiolate), i-mnt (2,2-dicyano-1,1-ethylenedithiolate)) have been synthesized and studied by a high-resolution FAB-MS, cyclic voltammetry and ³¹P NMR. (Dppf)Pt(i-mnt) exhibits one reversible redox peak at E_1/2 = 1.225 V and a strong Pt-P coupling constant (J_Pt-P = 3237 Hz) due to the electron-accepting property of i-mnt ligand. On the contrary, (dppf)Pt(mtdt) shows three reversible redox peaks corresponding to [dppf]^0/+ (E_1/2¹ = 0.470 V), [Pt(mtdt)]^0/+ (E_1/2² = 1.050 V) and [Pt(mtdt)]^+/2+ (E_1/2³ = 1.405 V) processes and a weak Pt-P coupling constant (J_Pt-P = 2962 Hz) due to relatively strong electron-donor property of mtdt ligand. X-ray structural analyses were performed for the three complexes: (dppf)PtL where L = dmit, phdt and i-mnt. The P₂PtS₂ core shows a distorted square planar geometry for the three complexes with P(1)-Pt-P(2) bite angle being larger than 96°. The S(1)-Pt-S(2) bite angle of the i-mnt complex is the smallest (74.42°) because of the formation of the four-membered ring.