5-(2-Pyridil)-1H-tetrazole complexes with Mo(iv) and W(iv) cyanides.

The reactions of tetrazole ligand derived from 2-cyanopyridine with K3Na[Mo(CN)4O2]·6H2O and K3Na[W(CN)4O2]·6H2O in water-ethanol solution result in isolation of two new complexes with the following formulae: (PPh4)2[Mo(CN)3O(pdt)]·2H2O (1) (Hpdt = 5-(2-pyridil)-1H-tetrazole) and (PPh4)2[W(CN)3O(pdt)]·3H2O (2). The complexes were characterized by elemental analysis, single crystal X-ray structure measurements, IR and UV-Vis spectroscopy, cyclic voltammetry measurement as well as thermogravimetric measurement. The X-ray crystal structure measurements indicated the presence of two coordination isomers in a single crystal. The pyridine nitrogen occupies both trans and/or cis position to the M[double bond, length as m-dash]O bond, which is explained by similar pK of pyridine and tetrazole nitrogen. The DTG measurements indicate the stabilization of tetrazole upon coordination.