Variable temperature inelastic neutron scattering study of chromium(II) Tutton salt: manifestation of the [formula omitted] Jahn–Teller effect

Abstract

Inelastic neutron scattering (INS) data are presented for the salt (ND 4) 2Cr(OD 2) 6(SO 4) 2, which enable the zero-field-splitting of the 5 A g ( C i ) ground term of the [Cr(OD 2) 6] 2+ cation to be defined in the temperature range 1.5–297 K. Above ∼100 K, the energies of the INS transitions are strongly temperature-dependent, as are the documented Cr–O bond lengths. The experimental data are interpreted using a 5E⊗e Jahn–Teller Hamiltonian perturbed by low symmetry strain. Good agreement is obtained using a parameter set analogous to that employed to describe the electronic and molecular structure of the [Cu(OD 2) 6] 2+ cation in the isostructural copper(II) salt.