SYNTHESIS, SPECTROSCOPIC CHARACTERIZATION OF THIOSEMICARBAZONE COMPLEXES OF NICKEL(II) AND X-RAY STRUCTURES OF ANISALDEHYDE THIOSEMICARBAZONE (ATSZH) AND BIS(TOLUALDEHYDE THIOSEMICARBAZONATO)NICKEL(II)

Complexes of nickel(II) with anisaldehyde (ATSZH), tolualdehyde (TTSZH), and vanillin (VTSZH) thiosemicarbazones have been synthesized and characterized by means of UV-Visible, I.R., Raman, H-1 and C-13 NMR spectroscopy. The thiosemicarbazones have been found to exist in the thione form. H-1 and C-13 NMR as well as electronic spectral data support a square planar structure for Ni(ATSZ)2 and Ni(TTSZ)2 complexes. H-1 and C-13 NMR spectra indicate that the structure of Ni(VTSZ)2 complex differs from the other two nickel(II) complexes and it may possibly consist of mixtures of isomers. The X-ray structures of Ni(TTSZ)2 and ATSZH were determined: the nickel complex is monoclinic with a = 26.412(6), b = 12.135(3), c = 6.888(1) angstrom, beta = 95.41(5)-degrees, Z = 4, R = 0.0647, space group C2/c. The structure consists of discrete Ni(TTSZ)2 molecules in which the metal, located on a symmetry centre, is N,S-chelated by two ligands forming two five-term chelate rings. The structure of ATSZH is also monoclinic: a = 7.859(1), b = 13.481(3), c = 10.028(3) angstrom, beta = 106.32(4)-degrees, Z = 4, R = 0.0412, space group P2(1)/c. The molecules, connected by N . . . O hydrogen bonds, reveal a considerable tilting of the aromatic ring in respect to the thiourea moiety if compared with the nickel structure.