New rhenium and zinc complexes of 2-formylpyridine N(4)-phenylthiosemicarbazone

Abstract

A New rhenium(V)-oxo, rhenium(III) and Zn(II) complexes [ReOCl2(L)],
[Re(L)2]Cl and [ZnCl2(HL)](where; HL = 2-formylpyridine-N(4)-
phenylthiosemicarbazone) have been synthesised and characterised. [ReOCl3(PPh3)2]
and [ReO4]- in presence of PPh3 have been used as a starting material to prepare
rhenium(V)-oxo and rhenium(III) complexes, while ZnCl2 is used to prepare the zinc
complex. The new complexes have been characterised by microanalyses, IR, (UV-Vis.),
1H, 13C NMR, mass spectroscopy and molar conductance. These studies show the Re(III)
ion is in a distorted octahedral environment with two tridentate deprotonated
thiosemicarbazone binding as monoanionic ligands through the sulfur, pyridyl nitrogen
and azamethinic nitrogen in which the complex does not result in isomeric mixtures. The
geometry about Re(V) ion is a distorted octahedral environment with one tridentate
deprotonated monoanionic ligand, two chloro ligands and oxo moiety. The NMR studies
(1H, 13C) of [ReOCl2(L)] show the existence of the complex in two isomers in solution.
On the other hand the geometry about Zn is a trigonal bipyramidal with one tridentate
ligand in thion form, and two chloro ligands.