Transition-metal chemistry of main-group hydrazides. Part 2. A new oxime thiosemicarbazide framework as a novel SN multifunctional tripodal ligand for palladium(II): synthetic and X-ray crystal structural investigations

Abstract

Thiosemicarbazide reacted with butane-2,3-dione oxime to give a Schiff-base product HL via the selective reaction of the hydrazine nitrogen atom. The ligating properties of this new oxime thiosemicarbazide ligand L with palladium(II) were investigated and in the complex [PdL(Cl)] 1 the palladium(II) atom is bound in a trimodal, cis arrangement to the oxime nitrogen, hydrazine nitrogen and the sulfur centre. The crystal structure of complex 1 further reveals that the oxime thiosemicarbazide HL has reacted with [PdCl₂(PhCN)₂] presumably via the elimination of HCl, in the thiol rather than the thione form. The hydrogen-bonding interaction of the oxime hydrogen that caused HL to be a dimer in the solid state is lost upon complexation with palladium(II), giving complex 1 a monomeric structure. X-Ray crystal data; for HL, monoclinic, space group P2₁/c, a= 11.082(4), b= 12.679(2), c= 6.101(2)Å, Z= 4, R= 0.044 and R′= 0.064; 1, triclinic, space group P, a= 7.660(3), b= 12.972(5), c= 22.325(8)Å, α= 89.26(3), β= 81.53(3), γ= 84.75(3)°, Z= 8, R= 0.045 and R′= 0.064.