Mono- and di-nuclear nickel(II) complexes with mixed N/S-donor ligands: Syntheses, structures and physical properties

Two new Ni(II) complexes are reported with tridentate thiosemicarbazone ligands derived from Schiff-base condensation with phenylthiosemicarbazide. Complex 1, a novel dinuclear Ni(II) complex of a SNS ligand synthesized by reaction with 2,2′-dithiodibenzaldehyde (DTDB), adopts a butterfly-type structure in which thiolates derived from DTDB reside in the bridging positions. Complex 2-(NO3)2, a mononuclear Ni(II) complex of a NNS ligand synthesized by reaction with pyridine carboxaldehyde features two ligands spanning three meridional positions on the pseudo-octahedral coordination sphere of the Ni(II) center. The thiosemicarbazone-S is coordinated to the Ni(II) center in 1 in the deprotonated anionic thiolate-S form, while the neutral thione-S is present in 2-(NO3)2. To the best of our knowledge complex 1 is the first example of a dinuclear bis(thiolate)-bridged Ni(II) complex with NS3 coordination involving a thiosemicarbazide moiety.