Synthesis, Characterization, Solid State Conductance and Thermal Studies of Trinuclear Cobalt(II) Tetrathiocyanatodiargentate(I) Complexes with Hydrazides and Hydrazones

Abstract

Cobalt(II) complexes of the type CoAg₂(SCN)₄-L (where L = benzoic acid hydrazide (BH), salicylic acid hydrazide (SH), anthraniiic acid hydrazide (AH), isonicotinic acid hydrazide (INH) and their isoproparcne derivatives viz. isopropanone benzoyl hydrazone (IBH), -salicoyl hydrazone (ISH), -anthranoyl hydrazone (IAH) and -isonicotinoyl hydrazone (IINH) were synthesised and characterized with the help of elemental analyses, electronic and IR spectra and magnetic moment data. The complexes are insoluble in common organic solvents but partially dissolve in DMSO and DMF. Cobalt(II) in the complexes has spin-free tetragonally distorted octahedral geometry. All the ligands are bicoordinate, bonding through >C=O and -Nh₂ or >C=N- groups except INH and IINH, where the pyridyl ring nitrogen and -NH₂ or -N=C> groups participate in bonding. SCN groups act as a bridge between two metal centres. Solid state conductance values suggest the semiconducting nature of the complexes. Thermal studies (TG, DTG and DTA) on CoAg₂(SCN)₄, CoAg₂(SCN)₄-BH and CoAg₂(SCN)₄.IBH indicate multiple decomposition steps which are both exothermic and endothermic.