Variable temperature inelastic neutron scattering study of chromium(II) Tutton salt:: manifestation of the 5E⊗e Jahn-Teller effect

Inelastic neutron scattering (INS) data are presented for the salt (ND4)(2)Cr(OD2)(6)(SO4)(2), which enable the zero-field-splitting of the (5)A(g)(C-i) ground term of the [Cr(OD2)(6)](2+) cation to be defined in the temperature range 1.5-297 K. Above similar to100 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 E-5 x 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(OD2)(6)](2+) cation in the isostructural copper(II) salt. (C) 2002 Elsevier Science B.V. All rights reserved.