Mössbauer effect study of tristetraphenylphosphonium tris(dicyanoethylene-1,2-dithiolato)iron: a 1,2-dithiolene complex of iron(III)

Abstract

The Mössbauer spectrum of ⁵⁷Fe in tristetraphenylphosphonium trisdicyano-1,2-dithioleneiron, (Ph₄P)₃[Fe{S₂C₂(CN)₂}₃], has been measured over a wide temperature range. Magnetic hyperfine broadening was observed as the temperature was lowered, due to increasing electron-spin relaxation times. A large quadrupole splitting was found, (½e²qQ=–1·85 mm s^–1 at 77 K), showing a strong distortion from cubic symmetry. The ground state of the low-spin ferric ion was found to be a d_xy hole well separated from higher states, in disagreement with conclusions previously drawn by Cotton and Gibson from e.p.r. data.