Heptaguanidinium sodium bis(penta-aquatetracosaoxoheptamolybdo-cobaltate) octahydrate

The title compound, (CH6N3)(7)Na[CoMo7O24(H2O)(5)](2) center dot 8H(2)O, features unusual [Co(H2O)(5)Mo7O24](4-) polymetallate anions. Two such anions are connected by a bridging octahedral sodium ion ( Na site symmetry 1) to form an {Na[( Co( H2O) 5)( Mo7O24)](2)}(7-) cluster. The Co - O and Mo - O distances are in the ranges 2.081 ( 11) - 2.121 ( 10) and 1.701 ( 8) - 2.508 ( 7) A, respectively. Together with the cluster, the charge-balancing guanidinium cations ( one of which is disordered about an inversion centre) and isolated water molecules form a three-dimensional supramolecular network by way of numerous O - H center dot center dot center dot O and N - H center dot center dot center dot O hydrogen bonds.