The title compound K3[HO{VO(O2)2}2]H2O has been synthesized and its crystal structure was determined by X-ray diffraction method. The crystal is of monoclinic, space group P21/c with a = 6.7078(3), b = 9.9539(6), c = 15.8182(9) ? = 93.702(3), V = 1053.96(10) ?, Mr = 414.20, Dc = 2.610 g/cm3, Z = 4, ?(MoKa) = 0.71073 ? F(000) = 808, = 3.014 mm-1, the final R = 0.0173 and wR = 0.0466 for 2178 observed reflections with I > 2s(I). X-ray diffraction reveals that the coordination polyhedra of V atoms are not chemically equivalent: the V(1) and V(2) polyhedra can be described as pentagonal pyramid and pentagonal bipyramid, respectively.
