Synthesis, spectral and structural studies of zinc(II) complexes of salicylaldehyde N(4)-phenylthiosemicarbazone

Five Zn(II) complexes of salicylaldehyde N(4)-phenylthiosemicarbazone (H2L) have been synthesized and physicochemically characterized. Out of the five Zn(II) complexes, one is binuclear {[(ZnL)2]·3C2H5OH (1)} and the other four are mononuclear {[Zn(HL)2]·C2H5OH (2), [ZnLbipy]·1/2H2O (3), [ZnLphen]·H2O (4) and [ZnLdmbipy] (5)} in nature. In complex 2, IR band due to ν(Zn–O) is absent and also the –OH signal due to the phenolic –OH group appears at δ = 11.38 ppm obtained from the 1H NMR spectrum supports the existence of free –OH group. Complexes 3–5 are heterocyclic base adducts and their IR spectra display bands characteristic of coordinated heterocyclic bases. The molecular structure of one of the complex 3 is resolved by single crystal X-ray diffraction studies. The complex 3 is orthorhombic with a space group P21cn. The Zn(II) in 3 is five coordinated and is having an approximately trigonal bipyramidal geometry with distortion from square based pyramid (TBDSBP).