Metal complexes of heteroarenes, X [1]. eta(1)-coordination of phosphinine: Synthesis and structure of cis-dichloro-bis(2,6-dimethyl-4-phenyl-phosphinine)platinum

Cis-Dichloro-bis(2,6-dimethyl-4-phenyl-eta(1)-phosphinine)platinum (3) has been prepared by ligand substitution from cis-dichloro(2,5-cyclooctadiene)p latinum and characterized by spectroscopy (H-1,C-13, P-31 NMR, IR, UV-Vis), CV and X-ray diffraction (space group P2(1)/c, a = 14.998, b = 16.540, c = 11.506 Angstrom, alpha = gamma = 90 degrees, beta = 92.46 degrees, Z = 4). In line with findings for similar P hybridization states, the Pt-P bond le ngth (221 pm) in 3 equals that in eta(1)-phosphaalkene Pt complexes and fal ls short of the respective parameters in Pt phosphane species. The stretchi ng frequencies nu(PtCl) and the bond length Pt-Cl indicate that phosphinine s and phosphaalkenes, relative to phosphanes, adopt a lower position on the trans-influence scale. This gradation is also suggested by the coupling co nstants (1)J(Pt-195,P-31).