Synthesis of Ni(II), Pd(II) and Pt(II) complexes containing chiral phosphino-thiol and -thioether ligands

The chiral P,S ligand 1-(diphenylphosphino)butane-2-thiol, L1H, and its thioether methyl derivative L1Me have been synthesized. L1H reacts with divalent Ni, Pd and Pt salts to form phosphinothiolato complexes of general formula [M(L1)Cl]2(1, M = Ni), (2, M = Pd), M(L1)2(3, M = Ni), (4, M = Pd), (5, M = Pt) and M(L1)(PR3)X, (6, M = Pd, R = Ph, X = Cl), (7, M = Pd, R =nBu, X = Cl), (8, M = Pt, R = Ph, X = H). Single crystal X-ray crystallography reveals a butterfly shape for the dimeric structures of nickel and palladium complexes, 1 and 2 respectively. The P,S chelate ring, according to solid state structural data and NMR analysis, adopts a preferred skewconformation for the S isomer and a conformation for the R isomer. Complex 6 dissociates in chloroform solutions to form the dimeric species 2 and free PPh3. Thermodynamic parameters for this process have been calculated.