The ground-state electronic structures of K3V(ox)3·3H2O, Na3V(ox)3·5H2O, and NaMgAl1−xVx(ox)3·9H2O (0 < x ≤ 1, ox = C2O42−) have been studied by Fourier-transform electronic absorption and inelastic neutron scattering spectroscopies. High-resolution absorption spectra of the 3Γ(t2g2) → 1Γ(t2g2) spin-forbidden electronic origins and inelastic neutron scattering measurements of the pseudo-octahedral [V(ox)3]3− complex anion below 30 K exhibit both axial and rhombic components to the zero-field-splittings (ZFSs). Analysis of the ground-state ZFS using the conventional S = 1 spin Hamiltonian reveals that the axial ZFS component changes sign from positive values for K3V(ox)3·3H2O (D ≈ +5.3 cm−1) and Na3V(ox)3·5H2O (D ≈ +7.2 cm−1) to negative values for NaMgAl1−xVx(ox)3·9H2O (D ≈ −9.8 cm−1 for x = 0.013, and D ≈ −12.7 cm−1 for x = 1) with an additional rhombic component, |E|, that varies between 0.8 and 2 cm−1. On the basis of existing crystallographic data, this phenomenon can be identified as due to variations in the axial and rhombic ligand fields resulting from outer-sphere H-bonding between crystalline water molecules and the oxalate ligands. Spectroscopic evidence of a crystallographic phase change is also observed for K3V(ox)3·3Y2O (Y = H or D) with three distinct lattice sites below 30 K, each with a unique ground-state electronic structure.