Synthetic, structural, and solution calorimetric studies of Pt(CH3)2(PP) complexes

Reaction enthalpies of the complex (COD)PtMe2 (1; COD = eta(4)-1,5-cyclooctadiene) with an extensive series of bidentate phosphines (dpype, dppf, diop, dppe, dppb, dppp, dpmcb, depe, dmpe, dcpce) have been measured by solution calorimetry. The relative stabilities of the resulting complexes PtMe2(PP) are determined by a combination of the donor and bite angle/ steric properties of the bidentate phosphine ligand. In general, good sigma donor ligands with small bite angles result in more thermodynamically stable complexes. Additionally, the molecular structures of 1, Pt(Me)(2)(pype) (2), Pt(Me)(2)(dppf) (8), Pt(Me)(2)(diop) (4), Pt(Me)(2)(dppe) (6), Pt(Me)(2)(dpmcb) (9), and Pt(Me)(2)(Et(2)dppp) (13) have been determined by single-crystal X-ray diffraction. No correlation between the thermochemical results and the structural parameters, e.g, M-P distance (as observed in other systems), is apparent in this class of complexes.