Magnetochemists have made great advances toward increasing the uniaxial anisotropy in single molecule magnets. Magnetostructural correlations of isolated paramagnetic transition metal compounds, however, has received less attention in recent decades. We present high-resolution Zeeman absorption spectra of the 3T1?1A1 intra-configurational spin-forbidden electronic transition of the V3+ ion in NaMgAl1-xVx(ox)3�9H2O (0<x=1) and K3V(ox)3�3H2O lattices (ox = oxalate, C2O42-). We previously studied these electronic transitions by Fourier transform absorption spectroscopy and determined a difference in sign for the axial component of the zero-field splitting parameter, D, for the V3+ ion in these two lattices despite the similarity in the coordination environment [Kittilstved, et al, Inorg. Chem., 2009  , 48, 7750]. Analysis of the Zeeman behavior clearly demonstrates large magnetic anisotropies of the ground state g-values for all systems studied. The anisotropy in the principal g-values is consistent with the difference in the signs of D between NaMgAl1-xVx(ox)3�9H2O and K3V(ox)3�3H2O. The observed splitting behavior of the 3T1 ground term for the V3+ ion in a pseudo-octahedral ligand field can be qualitatively reproduced within the angular overlap model (AOM) when considering real structural distortions of the coordination sphere. The AOM calculations reveal that the major contribution to the sign change in D originates from a rhombic distortion from bending of the proper rotational axes. We obtain an even better agreement between experiment and theory when accounting for the non-planar oxalate ligands known from reported crystal structures and scaling the angular overlap parameters to account for deviations in V-O bond lengths.

Zeeman spectroscopic study of pseudo-octahedral vanadium(III) in various trisoxalate crystals

246th National Meeting (2013)

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