Studies of dioxamide and dithio-oxamide metal complexes. Part 2. Synthesis and spectral characterisation of RNHC(S)C(S)NHR (R = alkyl or aryl) complexes with SbX3(X = Cl or Br), BiCl3, SnX4(X = Cl or Br), and TiCl4. Crystal and molecular structures of NN′-di-isopropyldithio-oxamide (L3) and SbCl3(L3)1.5

Abstract

The synthesis and characterisation of a variety of SbX₃L_1.5(X = Cl or Br), BiCl₃L₂, SnX₄L (X = Cl or Br), and TiCl₄L complexes [where L = RNHC(S)C(S)NHR for R = Me, Et, Prⁱ, Buⁿ, cyclo-C₆H₁₁, or CH₂Ph] is described. In all cases metal–sulphur bonds are formed following SS′-bidentate ligand attachment. The potential N-donor sites are not involved in co-ordination. The structural characterisation of the uncomplexed ligand PrⁱNHC(S)C(S)NHPrⁱ(L³) and the antimony(III) complex SbCl³(L³)_1.5(1) are reported. Crystals of (1) are rhombohedral, space group R with a= 11.80(1)Å, α= 60.1 (1)°, and Z= 2. 1 089 Unique data above background were collected and the structure refined to R 0.068. Crystals of L³ are monoclinic, space group P2₁/c with a= 6.226(7), b= 8.067(11), c= 11.187(12)Å, β= 91.0(1)°, and Z= 2. 635 Data above background were measured and the structure refined to R 0.077. The structure of (1) is a three-dimensional polymer. The octahedrally co-ordinated Sb atom lies on a three-fold axis and is strongly bound to three chlorine atoms [2.413(2)Å] and also weakly bound to three sulphur atoms from different ligands, which approach their positions trans to chlorine [Sb–S 3.197(5)Å] thus giving rise to an octahedral environment. There is no evidence for a stereochemically active lone pair associated with Sb^III. In the structure of L³ the sulphur atoms are mutually trans[C–S 1.680(7)Å] and this orientation is retained on complexation.