Structure and solution behaviour of cyclooctadiene complexes of platinum(II)

The substitution behaviour of [PtCl(R)(COD)] (R− = Me and Fc) complexes, by the stepwise addition of phosphine ligands, L (L = PPh3, PEt3 and P(NMe2)3), were investigated in situ by 1H and 31P NMR spectroscopy. Addition of less than two equivalents of the phosphine ligand results in the formation of dimeric molecules with the general formula trans-[Pt(R)(μ-Cl)(L)]2 for the sterically demanding systems where R− = Me/L = P(NMe2)3 and R− = Fc/L = PEt3, PPh3 and P(NMe2)3 while larger quantities resulted in cis- and trans mixtures of mononuclear complexes being formed. In the case of the relatively small steric demanding, strongly coordinating, PEt3 ligand the trans-[PtCl(R)(PEt3)2] mononuclear complexes were exclusively observed in both cases. The crystal structures of the two substrates, [PtCl(R)(COD)] (R− = Me or Fc), as well as the cis-[PtCl(Fc)(PPh3)2] substitution product are reported.