Spectroscopic and structural studies on cobalt complexes of the methyl esters of dithiocarbazic and 2-methyldithiocarbazic acids. Crystal structure of [Co{NH2NHC(S)SMe}{NH2NC(S)SMe}2]Cl·H2O

Abstract

The ligand behaviour of methyl esters of dithiocarbazic acid NH2NHC(S)SMe (HL) and of 2-methyldithiocarbazic acid NH2NMeC(S)SMe (MeL) in cobalt complexes has been investigated. Complexes of CoII and CoIII have been prepared under different conditions and characterized by their electronic and i.r. spectra. HL can act as a ligand when neutral or when deprotonated (L–); MeL can be deprotonated at the terminal N only after co-ordination. The crystal structure of [Co(HL)L2] Cl·H2O has been determined by X-ray diffraction methods: crystals are monoclinic, space group P21/c, Z= 4, in a unit cell of dimensions a= 12.085(9), b= 8.903(8), c= 17.287(16)A, and β= 104.2(1)°. The structure has been solved by Patterson and Fourier methods and refined by block-diagonal least squares to R= 0.042 for 1 993 reflections. It consists of cis-octahedral [Co(HL)L2]+ cations, in which one neutral and two deprotonated molecules of methyl dithiocarbazate act as chelating ligands, chloride anions, and water molecules, held together by a network of hydrogen bonds. The bond distances in the co-ordination polyhedron are: Co–S 2.203(4), Co–N 1.993(6)A for the neutral ligand; Co–S 2.212(5) and 2.218(3), Co–N 1.977(6) and 1.980(6)A for the deprotonated ligands. The conformation of the three ligands is cis,cis, i.e. with both NHNH2 and SMe groups bent towards the CS bond.