Cis-Dichloro-bis(2 ,6 -dimethyl-4 -phenyl-η1-phosphinine)platinum (3) has been prepared by ligand substitution from cis -dichloro(2,5-cyclooctadiene)platinum and characterized by spectroscopy (1H , 13C, 31P NMR, IR, UV-Vis), CV and X-ray diffraction (space group P21/c, a = 14.998, b = 16.540, c - 11.506 Å, α = γ = 90°, β = 92.46°, Z = 4). In line with findings for similar P hybridization states, the Pt-P bond length (221 pm) in 3 equals that in η1 -phosphaalkene Pt complexes and falls short of the respective parameters in Pt phosphane species. The stretching frequencies νPtCl and the bond length Pt-Cl indicate that phosphinines and phosphaalkenes, relative to phosphanes, adopt a lower position on the trans-influence scale. This gradation is also suggested by the coupling constants 1J(195Pt,31P).
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