The correlation between the stereochemistry and electronic structure of the [V(OH 2 ) 6 ] 3؉ cation has been examined using a variety of physical techniques in conjunction with angular overlap model calculations. The experimental data includes the 5rst reported high-5eld, 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(OH 2 ) 6 ] 3؉ cation was studied in samples formed from the co-crystallization of RbV(SO 4 ) 2 ' 12H 2 O and RbGa(SO 4 ) 2 ' 12H 2 O. The structural modi5cations of these salts di4er in terms of the orientation of the water molecules about the tervalent cation while the M III O 6 framework remains approximately octahedral. The electronic structure of the [V(OH 2 ) 6 ] 3؉ cation in samples of Rb[Ga:V] (SO 4 ) 2 ' 12H 2 O 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 -bonding normal to the plane of the water molecule is dominant over the in-plane interaction (e N !e # ca. 930 cm !1 for trigonal planar water coordination). The -anisotropy results in a large trigonal 5eld splitting of the 3 T 1g (O h ) ground term in RbV(SO 4 ) 2 ' 12H 2 O (1930 cm !1 ) which diminishes almost to zero when [V(OH 2 ) 6 ] 3؉ is doped into RbGa(SO 4 ) 2 ' 12H 2 O, 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(OH 2 ) 6 ] 3؉ cation and accounts for the structural abnormalities reported for vanadium(III) salts of this type.