Crystallographic and NMR studies of platinum(II) and palladium(II) η 3-methallyl trichlorostannate olefin complexes

Complexes of the type M(SnCl 3)η 3-CH 2C(CH 3)CH 2(olefin) (M = Pt, Pd; olefin = styrene, ethylene, norbornene) have been prepared and their 1H, 13C, and, in some cases, 119Sn and 195Pt NMR spectra recorded. Two-dimensional 1H NOE and 13C- 1H correlation methods were used for assignment purposes. The structures for the platinum- (1a) and palladium- (2a) styrene complexes have been determined by X-ray diffraction. The two compounds are isomorphous and crystallize in the triclinic space group P1 with cell constants a = 8.740 (2) Å, b = 9.338 (2) Å, c = 10.931 (2) Å, α = 72.43 (1)°, β = 89.38 (1)°, and γ = 73.33 (2)° for the Pd complex and a = 8.698 (2) Å, b = 9.373 (2) Å, c = 11.015 (2) Å, α = 72.32°, β = 89.76°, and γ = 73.30° for the Pt derivative. Both compounds have the olefin C-C vector almost parallel to the coordination plane (20.8 and 23.3° for 1a and 2a, respectively). Analyses of the NMR and crystallographic data lead to the conclusion that the SnCl 3 and olefin ligands both exercise a moderate trans influence with the former larger than the latter. Back-bonding from the metal to the olefin is suggested to be larger for Pt than Pd. © 1988 American Chemical Society.