Addition reactions on co-ordinated olefinic ligands. Part 8. Platinum(II) complexes of 1,1 -dimethylallene and their reaction with amines. Molecular structure of the zwitterionic derivative dichloro-[1-(NN-diethylammoniomethyl)-2-methylprop-1-enyl](triphenylphosphine) platinum(II)

Abstract

Some new platinum(II) complexes of 1,1-dimethylallene (dma) of general formula cis-[PtCl₂(dma)L](L = PPh₃, AsPh₃, H₂NC₆H₄Me-p, or SMe₂O) have been prepared. They react with aliphatic and aromatic amines to give zwitterionic alkenyl derivatives of the type cis-[PtCl₂(Me₂CCCH₂NR¹R²R³) L], which on treatment with hydrogen chloride afford the ammonium salts [NR¹R²R³(CH₂CHCMe₂)]Cl. The structure of the alkenyl complexes has been confirmed by X-ray diffraction analysis in the case of the title complex. Crystals are triclinic, space group P, with Z= 4 in a unit cell of dimensions a= 11.130(3), b= 18.887(5), c= 14.370(5)Å, α= 108.8(3), β= 90.1(2), γ= 95.1 (2)°. The structure has been solved by Patterson and Fourier methods and refined by block-diagonal least-squares to R= 0.10 for 3 630 observed reflections. The σ-bonded alkenyl group is perpendicular to the metal co-ordination plane. A short intramolecular contact between the nitrogen and a chlorine atom suggest the existence of a hydrogen bond.