The crystal and molecular structures of A(S2COCH2CH2CMe3)3, A = As(III), Sb(III) and Bi(III)

Abstract

Abstract The crystal and molecular structures of tris(3,3-dimethylbutyldithiocarbonato)-arsenic(III), -antimony(III) and -bismuth(III), A(S2COCH2CH2CMe3)3, have been determined at room temperature. The colorless crystals of A = As(III) are triclinic, space group P[unk] with unit cell dimensions a = 11.837(2) Å, b = 13.430(2) Å, c = 10.284(1) Å, α = 98.39(1)°, β = 102.472(9)°, γ = 101.73(1)°, Z = 2 and D x = 1.316 Mg m−3. The colorless crystals of A = Sb(III) are monoclinic, space group P21/c with unit cell dimensions a = 16.110(3) Å, b = 6.077(4) Å, c = 31.101(3) Å, β = 97.65(1)°, Z = 4 and D x = 1.439 Mg m−3. The yellow crystals of A = Bi(III) are also monoclinic, space group P21/c with unit cell dimensions a = 16.149(3) Å, b = 6.063(3) Å, c = 31.052(7) Å, β = 97.25(2)°, Z = 4 and D x = 1.632 Mg m−3 The structures were solved by direct methods and each refined by a full-matrix least-squares procedure to final R = 0.042 using 3118 reflections for A = As(III); to R = 0.051 using 3357 reflections for A = Sb(III); and to final R = 0.056 for 2606 reflections for A = Bi(III). The A = As(III) structure comprises isolated molecules with the central atom existing in a distorted capped octahedral geometry. A disorted pentagonal bipyramidal geometry is found in the A = Sb(III) structure where loose association, via Sb … S interactions, are found between centrosymmetrically related pairs. An analogous structure is found for A = Bi (III), however, relatively stronger Bi … S interactions are in existence. A discussion of the different motifs found for A(S2COR)3 structures indicates the importance of crystal packing effects, i.e. the desire to maximise A … S intermolecular contacts, in these structures.