Crystal structures of tris(diethyldithiocarbamato)-rhodium(III) and -arsenic(III)

Abstract

The crystal structures of the title compounds, [Rh(CS₂·NEt₂)₃], (I), and [As(CS₂·NEt₂)₃], (II) have been determined by-X-ray diffraction from diffractometer data, and refined by least-squares to R 0.080 (I) and 0.058 (II) for 1 582 and 1 877 reflections. Crystals are monoclinic, space group P2₁/a, with Z= 4 in unit cells of dimensions : (I)a= 18.07(3), b= 8.276(3), c= 15.80(1)Å, β= 96.35(4)°; (II)a= 18.543(4), b= 8.387(2), c= 15.870(3)Å, β= 101.05(2)°. The compounds are isomorphous also with the manganese(III) derivative; whereas the MS₆ core in (I) is quite close to D₃ symmetry (mean Rh–S 2.36₈Å), that of (II) is grossly distorted (as previously described) toward C₃ symmetry (mean As–S 2.84 and 2.34₉Å). In (II), the usual equality in the ligand C–S distances is destroyed as a result (mean C–S 1.68 and 1.76 Å) and the surrounding angular geometry of the ligand also distorted. The arsenic has a close hydrogen contact (3.2 Å) along the pseudo threefold axis from a neighbouring molecule.