The crystal and molecular structures of the title compounds have been determined from three-dimensional X-ray diffractometer data. Both complexes are isostructural and crystallize in the monoclinic space group P21/c (hereinafter SP is the ligand (2-vinylphenyl)diphenylphosphine). Cell parameters are as follows: Pt(CH3)2(SP), 1, a = 9.224 (4) Å,b= 18.521 (7) Å, c = 12.668 (5) Å,β = 119.19 (2)Δ, Z = 4; Pt(CF3)2(SP), 2, a = 9.3680 (5) Å,b= 19.3262 (6) Å, c = 12.6339 (9) Å, β = 117.35 (1)Δ, Z = 4. Block-diagonal and full-matrix least-squares refinement converged at = 0.026 (1, 3827 unique reflections) and R = 0.030 (2, 3058 unique reflections). The structures have approximately square-planar geometry with the SP ligand chelating via phosphorus and a π-bonded vinyl group which is almost normal to the metal coordination plane. Nonplanarity of the vinyl group in 2 was established by location and refinement of its hydrogen atoms. Important bond lengths are: 1, Pt-CH3 (trans to P) = 2.166 (5) Å, Pt-CH3 (trans to vinyl) = 2.052 (6) Å, Pt-P = 2.276 (1) Å, Pt-vinyl = 2.223 (5) and 2.201 (5) Å (terminal C); 2, Pt-CF3 (trans to P) = 2.082 (5) Å, Pt-CF3 (trans to vinyl) = 2.032 (5) Å, Pt-P = 2.310 (1) Å, Pt-vinyl = 2.290 (5) and 2.245 (5) Å (terminal C). The Pt-CF3 bonds in 2 are shorter than the analogous Pt-CH3 bonds in 1 whereas the opposite is true of the Pt-P and Pt-vinyl bonds. Although these bond-length trends can be interpreted in terms of Pt(dπ)-CF3((σ*) back-bonding, it seems more likely that the Pt-CF3 bond contraction is primarily a consequence of the positive charge induced on the σ-carbon atom by the electronegative fluorine atoms. The trends in Pt-P and Pt-vinyl bond lengths probably reflect a combination of two effects: (1) approximately equal σ-donor abilities or trans influences for CH3- and CF3- and (2) a cis-bond-weakening influence of unknown origin for the fluoroalkyl ligand which is also manifest from the structural comparison of PtClR(PMePh2)2 (R = CH3, 3; R = C2F5, 4). © 1979, American Chemical Society. All rights reserved.
