Influence of Jahn-Teller coupling on the magnetic properties of transitionmetal complexes with orbital triplet ground terms: Magnetization and electronic Raman studies of the titanium(III) hexa-aqua cation

Magnetization and electronic Raman data are presented for salts of the type Cs[Ga:Ti](SO4)(2). 12H(2)O, which enable a very precise definition of the electronic structure of the [Ti(OH2)(6)](3+) cation. The magnetization data exhibit a spectacular deviation from Brillouin behavior, with the magnetic moment highly dependent on the strength of the applied field at a given ra tio of B/T. This arises from unprecedented higher-order contributions to th e magnetization, and these measurements afford the determination of the gro und-state Zeeman coefficients to third-order. The anomalous magnetic behavi or is a manifestation of Jahn-Teller coupling, giving rise to low-lying vib ronic states, which mix into the ground state through the magnetic field. E lectronic Raman measurements of the 1%-titanium-(III)-doped sample identify the first vibronic excitation at similar to 18 cm(-1), which betokens a su bstantial quenching of spin-orbit coupling by the vibronic interaction. The ground-state Zeeman coefficients are strongly dependent on the concentrati on of titanium(III) in the crystals, and this can be modeled as a function of one parameter, representing the degree of strain induced by the cooperat ive Jahn-Teller effect. This study clearly demonstrates the importance that the Jahn-Teller effect can have in governing the magnetic properties of tr ansition metal complexes with orbital triplet ground terms.