  The solid solution Ga1-xGexV4S8 (x = 0 - 1) was synthesized by solid state
reactions and characterized by temperature-dependent x-ray powder diffraction
and static magnetic susceptibility measurements. The compounds crystallize in
the cubic GaMo4S8-type structure (space group F-43m), built up by
heterocubane-like [V4S4](5-x)+ cubes and [Ga1-xGexS4](5-x)- tetrahedra arranged
in a NaCl-like manner. The successive substitution of Ga3+ by Ge4+ increases
the electron count in the molecular orbital (MO) of the V4-cluster gradually
from seven to eight. We observe an almost linear increase of the magnetic
moments, connected with a transition from ferromagnetic to antiferromagnetic
ordering around x <= 0.5. Remarkably, the low temperature structural phase
transitions as known from the ternary compounds were also detected in the solid
solution. The gallium-rich compounds (0 < x < 0.5) undergo rhombohedral
distortions like GaV4S8 (space group R3m), whereas distortions to orthorhombic
symmetry (space group Imm2) as known from GeV4S8 occur in the germanium-rich
part of the solid solution (0.5 <= x < 1).
