Structural Preferences in Phosphanylthiolato Platinum(II) Complexes

The transition‐metal complexes of heterotopic phosphanylthiolato ligands are useful in various reactions which depend on the stereochemistry of the complexes. Bis‐chelate complex [Pt(SCH(2)CH(2)PPh(2)‐κ(2) P,S)(2)] (1) was obtained in good yields by direct base‐free substitution reaction of the corresponding phosphanylthiol (HSCH(2)CH(2)PPh(2)) with K(2)PtCl(4) or by oxidative addition of the same phosphanylthiol to Pt(PPh(3))(4). In agreement with the antisymbiosis rule, complex 1 shows a cis‐P,P arrangement in solid state crystallizing in the monoclinic system (C2/c). Density functional theory (DFT) calculations on 1 reveal the right characteristics for the preferred cis‐P,P arrangement, rationalizing its formation. Direct base‐free reaction of [PtCl(2)(1,5‐cyclooctadiene)] with one equivalent of the same phosphanylthiol produce the trinuclear complex [PtCl(μ‐SCH(2)CH(2)PPh(2)‐κ(2) P,S)](3) (2) instead of the binuclear structure common in palladium and nickel derivatives. Crystals of 2 are triclinic (P [Formula: see text] ) showing a sulfur‐bridging edge‐sharing cyclic trinuclear complex with square‐planar coordination geometry around the platinum atoms and a Pt(3)S(3) cycle in skew‐boat conformation. This preference for the trinuclear structure was rationalized mechanistically and through conceptual DFT.