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

Abstract

Ground-state spin-Hamiltonian parameters, magnetic data, and electronic Raman spectra of hexacoordinate vanadium(III) complexes are calculated with consideration to the ((3)A (3)E) e vibronic interaction and compared to experimental data. It is shown that the zero-field-splitting of the (3)A(g) (S(6)) ground term may be reduced significantly by the dynamical Jahn-Teller effect, particularly when the pi-anisotropy of the metal-ligand bonding interaction is significant, and the energy of the Jahn-Teller active vibration is comparable to the diagonal axial field. The dynamical Jahn-Teller effect may also give rise to a significant enhancement in the Raman intensity of overtones and higher harmonics of Jahn-Teller active vibrations, when the energies of these transitions fall in the proximity of intra-(3)T(1g) (O(h)) electronic Raman transitions. A simple method of conducting vibronic coupling calculations is described, employing ligand field matrices generated by angular overlap model calculations, which may in principle be applied to any transition metal complex.

Electronic structure of V3+ in NaMgAl(ox)3·9H2O probed by Fourier transform spectroscopy

“…A nice example is the class of [V(OH 2 ) 6 ] 3+ -alums where the axial crystal field is ca. 3 times larger than that of [V(ox) 3 ] 3À , and the site symmetry is strictly trigonal (C 3(v) ) [20]. However, we attribute the additional splitting to a large rhombic crystal field present in the title lattice.…”

A perspective on applications of ligand-field analysis: inspiration from electron paramagnetic resonance spectroscopy of coordination complexes of transition metal ions

“…In this complex, the ammine ligands are pure σ-donors, in contrast to the complicated, anisotropic π-bonding that is found for aqua ligands, which leads to extensive ZFS for nominally octahedral, HS hexaaqua complexes. [32][33][34] In addition, the octahedral d 8 ) and 330 GHz (11 cm -1 ), typical for HFEPR. Only with the last of these is a magnetic dipole allowed transition possible at an accessible magnetic field. )…”

“…2+ has a small ZFS, presumably arising from anisotropy in the aqua ligands, as described for other highspin ions by Tregenna-Piggott. 30,[32][33][34] In these cases, a trigonal splitting results, which for V II as a dopant in corundum (Al 2 2+ as in the oxide lattice.…”

“…24 Another locus of these older theories is the place where they were brought into full flower, Copenhagen, Denmark. The work by Jesper Bendix [25][26][27] and Høgni Weihe 28 and their co-workers in Copenhagen, together with Philip L. W. TregennaPiggott in Switzerland, [29][30][31][32][33][34][35][36][37] represent superb examples of state-of-the-art experimental (not only HFEPR, but also optical and vibrational spectroscopy, and most significantly, inelastic neutron scattering (INS) 31 ) and computational studies. In particular, Bendix has directly compared LFT to the current luminary, DFT.…”

Aminocarboxylate complexes of vanadium(III): Electronic structure investigation by high-frequency and -field electron paramagnetic resonance spectroscopy

“…This difficulty of observing EPR can be overcome by the use of high frequencies going into sub-THz and THz range (on the order of 100 cm À1 ) with correspondingly high resonant magnetic fields (up to 45 T in a continuous mode at the NHMFL in Tallahassee; higher fields operated in a pulsed mode are used at the NHMFL operation in Los Alamos, and elsewhere [13]). This technique is referred to as HFEPR and has been successfully applied to a wide variety of non-Kramers systems [14,15], including V(III) [16][17][18][19][20][21]. All of these systems were studied in the solid state, usually as a pure powder, although in some cases as a doped single crystal [17,19].…”