Syntheses, characterization and X-ray crystal structures of a mono- and a penta-nuclear nickel (II) complex with oximato Schiff base ligands

Abstract

A mononuclear octahedral nickel (II) complex [Ni(HL¹)₂](SCN)₂] (1) and an unusual penta-nuclear complex [{(NiL²)(μ-SCN)}₄]Ni(NCS)₂]]•2CH₃](CN (2) where HL¹ = 3-(2-aminoethylimino)butan-2-one oxime and HL² = 3-(hydroxyimino)butan-2-ylidene)amino)propylimino)butan-2-one oxime have been prepared and characterized by X-ray crystallography. The mono-condensed ligand, HL¹, was prepared by the 1:1 condensation of the 1,2-diaminoethane with diacetylmonoxime in methanol under high dilution. Complex 1 is found to be a mer isomer and the amine hydrogen atoms are involved in extensive hydrogen bonding with the thiocyanate anions. The dicondensed ligand, HL², was prepared by the 1:2 condensation of the 1,3-diaminopropane with diacetylmonoxime in methanol. The central nickel (II) in 2 is coordinated by six nitrogen atoms of six thiocyanate groups, four of which utilize their sulphur atoms to connect four NiL² moieties to form a penta-nuclear complex and it is unique in the sense that this is the first thiocyanato bridged penta-nuclear nickel (II) compound with Schiff base ligands.