Abstract
Single crystals of Co
3
(PO
4
)
2
·4H
2
O, tricobalt(II) bis[orthophosphate(V)] tetrahydrate, were obtained under hydrothermal conditions. The title compound is isotypic with its zinc analogue Zn
3
(PO
4
)
2
·4H
2
O (mineral name hopeite) and contains two independent Co
2+
cations. One Co
2+
cation exhibits a slightly distorted tetrahedral coordination, while the second, located on a mirror plane, has a distorted octahedral coordination environment. The tetrahedrally coordinated Co
2+
is bonded to four O atoms of four PO
4
3−
anions, whereas the six-coordinate Co
2+
is
cis
-bonded to two phosphate groups and to four O atoms of four water molecules (two of which are located on mirror planes), forming a framework structure. In addition, hydrogen bonds of the type O—H⋯O are present throughout the crystal structure.