Synthesis and crystal structure of some dioxomolybdenum(VI) complexes with thiosemicarbazonato ligands

Abstract

Thiosemicarbazones are ligands with interesting ONS donor and chelating properties. Some of their metal complexes have been found to be cancerostatic [1]. Mononuclear dioxomolybdenum(VI) [MoO2L1L2] complexes with thiosemicarbazonato ligands have been prepared by the reaction of [MoO2(acac)2] with L1 = o-vanilin 4-phenylthiosemicarbazone (I and II) and salicylaldehyde 4-phenylthiosemicarbazone (III and IV) with addition of appropriate amine (L2 = bipyridine (I and III), pyridine (II) and g-picoline (IV)) [2, 3, 4]. Complex I crystallises in the monoclinic space group P21/c with cell parameters: a=10.692(2), b=14.764(2), c=14.009(2)A ; , betha= 108.844(2)o ; , R1=0.0497 for 4629 Fo>4s(Fo). Complex II crystallises in the monoclinic space group P21/n with cell parameters: a=10.7877(9), b=15.3255(11), c=12.926(1) A ; , betha=107.933(8)o ; , R=0.055 for 8013 Fo>4s(Fo). Complex III crystallises in the triclinic space group P-1 with cell parameters: a=10.780(2), b=10.936(1), c=11.808(1) A ; , alpha=84.952(8), betha=82.580(9), gamma=64.987(13) )o ; , R=0.059 for 7363 Fo>4s(Fo). Complex IV crystallises in the orthorhombic space group Pbca with cell parameters: a=10.7877(9), b=15.3255(11), c=12.926(1) A ; , R=0.0603 for 5512 Fo>4s(Fo). In all structures molybdenum is coordinated by a tridentate ONS chelating ligand, two oxo groups and N-donor ligands in a disturbed octahedral coordinations. The Mo=O bond length in these cis-dioxomolybdenum complexes is in range 1.6896(22) to 1.7101(25) A ; . [1] U. Abram, K. Ortner, R. Gust, K. Sommer, J.Chem . Soc Dalton, (2000)735. [2] D. Chattopadhyay & S. K. Mazumdar, Acta Cryst. C44 (1988) 1025-1028. [3] S. Purohit, A. P. Kaley, L. S. Prasad, P. T. Monoharan & S. Ghosh, Inorg Chem 28 (1989) 3735. [4] J. U. Mondal, J. G. Zamora, M. D. Kinon & F. A. Schultz, Inorg. Chim. Acta 309 (2000) 147.