  We present the observation of an isostructural Mott insulator-metal
transition in van-der-Waals honeycomb antiferromagnet V$_{0.9}$PS$_3$ through
high-pressure x-ray diffraction and transport measurements. The MPX$_3$ family
of magnetic van-der-Waals materials (M denotes a first row transition metal and
X either S or Se) are currently the subject of broad and intense attention, but
the vanadium compounds have until this point not been studied beyond their
basic properties. We observe insulating variable-range-hopping type resistivity
in V$_{0.9}$PS$_3$, with a gradual increase in effective dimensionality with
increasing pressure, followed by a transition to a metallic resistivity
temperature dependence between 112 and 124 kbar. The metallic state
additionally shows a low-temperature upturn we tentatively attribute to the
Kondo Effect. A gradual structural distortion is seen between 26-80 kbar, but
no structural change at higher pressures corresponding to the insulator-metal
transition. We conclude that the insulator-metal transition occurs in the
absence of any distortions to the lattice - an isostructural Mott transition in
a new class of two-dimensional material, and in strong contrast to the behavior
of the other MPX$_3$ compounds.
