Crystal structure of tris-(NN-diethyldithiocarbamato)manganese(III)

Abstract

The crystal and molecular structure of the title compound has been determined from single-crystal X-ray photographic data. The structure was solved by conventional Patterson and Fourier heavy-atom methods, and refined by block-diagonal least-squares techniques to R 0·11 for 1059 independent observed reflections. Crystals are monoclinic, space group P2₁/a, a= 18·04 ± 0·02, b= 8·34 ± 0·02, c= 15·88 ± 0·03 Å, β= 96·7 ± 0·1°, Z= 4. The molecule consists of three diethyldithiocarbamate ligands surrounding a central manganese atom, chelating through the sulphur atoms and being substantially planar. The outer geometry of the ligands compares well with that determined in similar structures. The inner geometry of the Mn(CS₂)₃ molecular core does not conform to the usual D₃ point-symmetry of transition-metal complexes of this type but shows heavy distortion, the manganese environment consisting of three approximately opposing and equivalent pairs of manganese–sulphur bonds of length 2·38(1), 2·43(1), and 2·55(1)Å. The remainder of the inner geometry is similarly irregular, with C–S 1·65–1·77 Å and C–S–Mn 82–90°. This large distortion is attributed to the ⁵E_g(O_h approximation) electronic ground state of the molecule which is expected to be susceptible to heavy Jahn–Teller distortion. Additional evidence is provided by band deformation in the i.r. spectrum.