The study of the influence of Jahn-Teller coupling and low symmetry strain on the anomalous electron paramagnetic resonance spectrum of titanium(III) doped CsAl(SO4)2⋅12H2O

Abstract

The controversial EPR spectrum of titanium͑III͒ as an impurity in cesium aluminum sulphate alum has been reexamined using conventional CW-and a novel pulsed-EPR technique, which monitors the nutation frequency as a function of field. The CW-spectra display a high degree of structure, which is interpreted as arising from chemically distinct titanium͑III͒ species. The two-dimensional nutation spectrum maps the g ʈ vs g Ќ relation from just one crystal orientation, and to far greater precision than available from CW-EPR. This novel technique shows that the origin of the linewidths observed for some of the EPR lines is inhomogeneous broadening, the nature of which can be described adequately only in the two-dimensional nutation spectrum. Calculations of g ʈ vs g Ќ have been undertaken by numerical diagonalization of the vibronic Hamiltonian. It is found that the relationship between g ʈ and g Ќ can be modeled only by assuming that the titanium͑III͒ ions are subject to both dynamic Jahn-Teller coupling and low symmetry strain. Furthermore, it is shown that the calculated g ʈ vs g Ќ relation is strongly dependent upon the nature of the vibronic interaction assumed. An excellent reproduction of the experimental data is obtained, using parameters consistent with those employed to model the susceptibility data of the isostructural cesium titanium sulphate alum.

Structure and Bonding of the Vanadium(III) Hexa-Aqua Cation. 2. Manifestation of Dynamical Jahn−Teller Coupling in Axially Distorted Vanadium(III) Complexes

“…The magnitudes of the vibronic coupling constants may be estimated by way of DFT − or AOM − calculations. For the [V(OH 2 ) 6 ] 3+ cation, coupling between the 3 T 1g ( O h ) ground term and the ρ τ twisting libration of water is expected to be prevalent, on the basis of an extensive experimental and theoretical study of the [Ti(OH 2 ) 6 ] 3+ cation. − The form of the twisting libration is depicted in Figure of ref . In the β-alums, the librational modes of water coordinated to the tervalent cation are strongly coupled, occurring between ∼750 and ∼950 cm -1 in the hydrogenous salt, and between 550 and 700 cm -1 in the deuteriated salt .…”

Influence of Jahn−Teller Coupling on the Magnetic Properties of Transition Metal Complexes with Orbital Triplet Ground Terms: Magnetization and Electronic Raman Studies of the Titanium(III) Hexa-Aqua Cation

“…Comparison of plots LF and JT in Figure shows that the increase in W (1) as a function of strain is greatly enhanced by the Jahn−Teller effect. For a detailed discussion of the dependence of the ground-state g values of this system ( g ≡ 2 W (1) ) on strain and Jahn−Teller coupling, refer to refs and ; the dependence of W (2) on E JT and e θ has not been addressed before and is of primary interest here. Coupling of the electronic states to the low-energy mode at 53 cm -1 is largely responsible for the dramatic increase in the magnitude of the ground-state value of W (2) , and this can be illustrated using a simple perturbation model.…”

“…8.7 Å) would suggest this to be an ideal host in which to study the magnetic behavior of a 3d 1 complex. However, only recently, due to the combined efforts of a number of groups, has certain progress towards defining the electronic structure of the [Ti(OH 2 ) 6 ] 3+ cation in this ostensibly simple system been made. − The complexity arises from a delicate balance between spin−orbit and Jahn−Teller coupling, as revealed from a detailed analysis of the variation of the effective magnetic moment with temperature for CsTiSH and titanium(III) doped into the isostructural Cs(OH 2 ) 6 Ga(OH 6 ) 6 (SO 4 ) 2 salt (CsGaSH, Cs[Ga:Ti]SH) . The study was confined to the temperature range of 15−295 K, where the [Ti(OH 2 ) 6 ] 3+ cation is axially symmetric.…”

Isolated Ti(III) Species on the Surface of a Pre-active Ziegler Natta Catalyst

“…On the other hand, in the case of an octahedral coordination and tetragonal compression, the ground state is the d xy orbital, while if the distortion is a tetragonal elongation, the ground state is a degenerate d xy , d yz orbital, subjected to Jahn-Teller effect that further resolves the degeneracy [27][28][29][30]. The g value expressions for a Ti 3+ ion in a tetragonally distorted octahedral environment are thus:…”