Reactions of platinum(II) acetylides with organolithium compounds: formation of lithium-bridged dinuclear platinum(II) complexes and of triorganoplatinate(II) complexes: crystal structure of the complex [Pt2(CCPh)4(PEt3)2(Bun)2(µ-Li)2]

Abstract

Platinum(II) acetylides of the type trans-[Pt(CCR¹)₂(PEt₃)₂](1)(R¹= Me, Buⁿ, or Ph) lose one equivalent of PEt₃ on treatment with organolithium reagents LiR²(2)(R²= Buⁿ, Bu^t, or Ph) in hydrocarbon solvents to give the dinuclear complexes [Pt₂(CCR¹)₄(PEt₃)₂(R²)₂(µ-Li)₂](3), containing a PtLi₂Pt unit. In the presence of better donors (e.g. Et₂O, tetrahydrofuran, or NNN′N′-tetramethylethylenediamine) solvation of lithium breaks this dimeric structure leading to the anions (4) of the type trans-[Pt(CCR¹)₂(PEt₃)R²]^–. Reaction of the anion (4d)(R¹= Ph, R²= Buⁿ) with a further equivalent of LiR²(R²= Buⁿ) gave Li(CCPh) and another anion, cis-[Pt(CCPh)(PEt₃)(Buⁿ)₂]^–. Multinuclear n.m.r. (¹H, ⁷Li, ¹³C, ³¹P, and ¹⁹⁵Pt) has been used to characterize the highly reactive compounds in solution. The crystal structure of complex (3d)(R¹= Ph, R²= Buⁿ) has been determined, which crystallises in space group P2₁/n, with a= 14.061(4), b= 18.408(4), c= 19.737(7)Å, and Z= 4.