Nickel(II) complexes of ONS and ONN chelating thiosemicarbazones with triphenylphosphine co-ligands

Abstract

Reactions of 5-bromo-2-hydroxy-benzaldehyde-S-R-4-R-1-thiosemicarbazones, [R, R-1 = H,H (L-1); CH3, H (L-2); H, C6H5 (L-3); CH3, C6H5 (L-4)] with [Ni(PPh3)(2)Cl-2] in 1:1 molar ratio yielded complexes of general formula [Ni(L)(PPh3)]. While the complexes of L-1 and L-3 involve the ONS donor set of the thiosemicarbazone, the L-2 complexes utilize the ONN set. The reaction of L-4 and the nickel salt gave the L-3 complex by loss of the CH3 group from the sulphur. The complexes were characterized by physico-chemical and spectroscopic methods. The structures of the L-1 and L-2 complexes have been determined by single crystal X-ray diffraction and a new coordination mode (ONN) of salicylaldehyde thiosemicarbazones has been identified.