The crystal and molecular structure of (C 6H 5s) 3AsFe(S 2C 2{CF 32}) 2, a monomeric, five-coordinate dithiolene complex of iron

Abstract

The crystal and molecular structure of the title compound shows it to be monomeric in the solid state. The central iron atom has a square-pyramidal coordination geometry defined by the two perfluoromethyldithiolene methyldithiolene ligands and the As atom of the axial (C 6H 5) 3As group. The crystals are triclinic with a = 12.537(7), b = 12.805(4), c = 10.436(7) Å, α = 96.67(4), β =92.30(2), γ = 11.21(6)°, ϱ o = 1.79(2), ϱ c = 1.82 gm cm 3 and z = 2. Least squares refinement of the positional and anisotropic thermal parameters yield final discrepancy factors of R 1(F) = 0.047 and R 2(F) = 0.059 for the 3703 structure factors with F 2 o ⩾ 3σ(F 2 o. The bonding parameters of the S-C-C-S fragment of the perfluoromethyldithiolene are closer to a dithioketone than a dithiol. The iron atom is not in the plane of the four sulfurs; instead, it is displaced 0.23 Å from the basal plane. The Fe-S bonds are short and range in length from 2.145(2) to 2.154(2) Å. The C-S bond lengths have an average value of 1.702 Å which is significantly shorter than those found for maleonitriledithiol complexes. The Fe-As distance of 2.325(2) Å is a little longer than the ones found for iron-arsine complexes of olefins. Short As-S intramolecular contacts were found in this molecule.