N,N′-disubstituted dithiomalonamide complexes of antimony(III). Crystal and molecular structure of [SbCl3{C2H5NHC(S)CH2C(S)NHC2H5}] with lone-pair occupation of an antimony co-ordination site

Abstract

Direct addition of antimony(III) trichloride to N,N′-disubstituted dithiomalonamides, RHNC(S)CH₂C(S)NHR (R = CH₃, C₂H₅, i-C₃H₇, n-C₄H₉, or cycle-C₆H₁₁), gives rise to 1:1 complexes. I.r. and n.m.r. data suggest that the complexes have equivalent structures and the crystal structure of a representative, [SbCl₃{C₂H₅NHC(S)CH₂C(S)NHC₂H₅}], has been determined. Crystals are monoclinic, space group P2₁, a= 10.841(8), b= 8.276(9), c= 10.185(11)Å, β= 120.9(1)°, and Z= 2.558 Independent data above background have been refined to R= 0.099. The antimony atom is bonded to three chlorine atoms [Sb–Cl 2.344(17), 2.580(14), 2.576(15)Å] and two sulphur atoms of the bidentate thiomalonamide [2.66(1), 2.74(2)Å]. The antimony environment is six-co-ordinate octahedral with the lone pair occupying one site.