Influence of the Mode of Water Coordination on the Electronic Structure of the [V(OH2)6]3+ Cation

• Published in: Journal of solid state chemistry Vol. 145; no. 2; pp. 460 - 470
• Main Authors: Tregenna-Piggott, Philip L.W., Best, Stephen P., Güdel, Hans U., Weihe, Høgni, Wilson, Chick C.
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.07.1999; Elsevier
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Crystal and ligand fields; Electron density of states and band structure of crystalline solids; Electron states; Exact sciences and technology; Level splitting and interactions; Other inorganic compounds; Physics; Raman spectra; Inorganic compounds; Vanadium sulfates; ESR; Transition element compounds; Stereochemistry; Lattice vibrations; Experimental study; Gallium sulfates; Rubidium sulfates; Electronic structure; Ligand field; Absorption spectra; Hydrates
• ISSN: 0022-4596; 1095-726X
• DOI: 10.1006/jssc.1999.8154

The correlation between the stereochemistry and electronic structure of the [V(OH2)6]3+] cation has been examined using a variety of physical techniques in conjunction with angular overlap model calculations. The experimental data includes the first reported high-field, high-frequency EPR study of a vanadium(III) complex which enables a precise determination of the ground term spin-Hamiltonian parameters. The electronic structure and vibrational spectrum of the [V(OH2)6]3+ cation was studied in samples formed from the co-crystallization of RbV(SO4)2·12H2O and RbGa(SO4)2·12H2O. The structural modifications of these salts differ in terms of the orientation of the water molecules about the tervalent cation while the MIIIO6 framework remains approximately octahedral. The electronic structure of the [V(OH2)6]3+ cation in samples of Rb[Ga:V](SO4)2·12H2O is found to depend greatly on the relative proportions of gallium(III) and vanadium(III). The experimental data are in accordance with predictions based on the angular overlap model when the π-bonding normal to the plane of the water molecule is dominant over the in-plane interaction (eπ⊥−eπ∥ ca. 930 cm−1 for trigonal planar water coordination). The π-anisotropy results in a large trigonal field splitting of the 3T1g (Oh) ground term in RbV(SO4)2·12H2O (1930 cm−1) which diminishes almost to zero when [V(OH2)6]3+ is doped into RbGa(SO4)2·12H2O, on account of the change in the orientation of the water molecules imposed by hydrogen bonding constraints. This work demonstrates the strong correlation between the stereochemistry and electronic structure of the [V(OH2)6]3+ cation and accounts for the structural abnormalities reported for vanadium(III) salts of this type.