Balance, uniformity, and asymmetry of the structure of volborthite Cu(OH)(VO)·2HO

Four structural models of volborthite Cu(OH)(VO)·2HO ( = 10.646(2) Å, = 5.867(1) Å, = 14.432(2) Å, β = 95.19(1)°, = 897.7(5) Å, = 4, = 0.038/0.046) calculated in the space groups determined from the systematic absences are compared. Based on the structure balance and the similarity of constituting polyhedra, values of the factor, and isotropic thermal parameters, the space group is found to be preferable, which is the only possible asymmetric and uniform variant. Hydrogen atoms of OH-groups, oxygen atoms and, partially, hydrogen atoms of water are localized.