Transition-metal complexes of cyclohexane-1,2-dione bis(thiosemicarbazone)(H2L). Crystal structures of [ZnL(OH2)]·dmf (dmf = dimethylformamide) and [Zn(H2L)Cl]Cl·2H2O

Abstract

The reaction of chlorides and acetates of Fe^II, Ni^II, Cu^II and Zn^II with the polydentate ligand cyclohexane-1,2-dione bis(thiosemicarbazone)(H₂L) led to the formation of some novel complexes which have been characterized by spectroscopic methods (NMR, IR). The crystal structures of the two compounds [ZnL(OH₂)]·dmf (dmf = dimethylformamide)1 and [Zn(H₂L)Cl]Cl·2H₂O 2 have been determined. In both complexes the co-ordination geometry about zinc is distorted square-planar pyramidal. The axial sites are occupied by a water molecule in 1 or by a chlorine atom in 2. The ligand is dideprotonated in 1 and neutral in 2, so that in 1 a higher π-delocalization is observed.