Thermal behaviour and crystal structure of dichlorobis(methyl 2-methyldithiocarbazate-N3S)cobalt(II)–methyl 2-methyldithiocarbazate (2/1), [Co{NH2NMeC(S)SMe}2Cl2]·0.5[NH2NMeC(S)SMe]

Abstract

The crystal structure of [Co^II(MeL)_2.5Cl₂](MeL = methyl 2-methyldithiocarbazate) has been determined by X-ray diffraction methods in order to define the unusual stoicheiometry of the compound. Crystals are tetragonal, space group l4₁/acd, Z= 16, in a unit cell of dimensions a= 12.23(1) and c= 51.02(2)Å. The structure has been solved by Patterson and Fourier methods and refined by full-matrix least squares to R= 0.068 for 615 independent observed reflections. It consists of octahedral [Co(MeL)₂Cl₂] units, having C₂ crystallographic symmetry, where the two MeL molecules act as chelating ligands, and of free, disordered MeL molecules. The complexes are joined in layers by N–H ⋯ Cl hydrogen bonds and the MeL molecules occupy the interlayers empty space. The bond distances in the Co co-ordination polyhedron are: Co–S = 2.446(7), Co–N = 2.174(17), and Co–Cl = 2.417(6)Å. The thermal behaviour [Co(MeL)_2.5Cl₂] has been studied by thermal gravimetric analysis (t.g.a.) and differential scanning calorimetry (d.s.c.). Evidence for the reaction 2[Co(MeL)₂Cl₂]·0.5MeL →[Co(MeL)₃][CoCl₄]+ MeL has been obtained.