The distorted tetrahedral
[V(OAd)<sub>4</sub>] alkoxide (OAd =
1-adamantoxide, complex <b>1</b>) is the first homoleptic, mononuclear
vanadium(IV) alkoxide to be characterized in the solid state by X-ray
diffraction analysis. The compound crystallizes in the cubic <i>P</i>4̅3<i>n</i> space group with two highly
disordered, crystallographically independent molecules in the asymmetric
unit. Spin Hamiltonian parameters extracted from low temperature X-
and Q-band electron paramagnetic resonance (EPR) experiments performed
for polycrystalline samples of <b>1</b>, both in the concentrated
(bulk) form and diluted in the diamagnetic [Ti(OAd)<sub>4</sub>] analogue,
reveal a fully axial system with <i>g</i><sub><i>z</i></sub> < <i>g</i><sub><i>x</i></sub>, <i>g</i><sub><i>y</i></sub> and <i>A</i><sub><i>z</i></sub> ≫ <i>A</i><sub><i>x</i></sub>, <i>A</i><sub><i>y</i></sub>. Complex <b>1</b> has also been characterized by alternate
current susceptometry with varying temperature (3–30 K) and
static magnetic field (up to 8.5 T), showing field-induced slow relaxation
of the magnetization with relaxation times ranging from ca. 3 ms at
3 K to 0.02–0.03 ms at 30 K, in line with relevant results
described recently for other potential molecular quantum bits. Pulsed
EPR measurements, in turn, disclosed long coherence times of ca. 4
μs at temperatures lower than 40 K, despite the presence of
the H-rich ligands. The slow spin relaxation in <b>1</b> is
the first observed for a tetracoordinate nonoxido vanadium(IV) complex,
and results are compared here to those generated by square-pyramidal
V<sup>IV</sup>(O)<sup>2+</sup> and trigonal prismatic V<sup>4+</sup> with oxygen donor atom sets. Considering that the number of promising
d<sup>1</sup> complexes investigated in detail for slow magnetization
dynamics is still small, the present work contributes to the establishment
of possible structural/electronic correlations of interest to the
field of quantum information processing
