Penta-kis(2-oxo-2,3-dihydro-pyrimidin-1-ium) di-μ(3)-chlorido-tri-μ(2)-chlorido-hexa-chloridotricadmate(II).

The title compound, (C4H5N2O)5[Cd3Cl11], was obtained from the reaction of 2-hydroxy­pyrimidine hydro­chloride and cadmium(II) chloride in concentrated HCl solution. The crystal structure consists of planar 2-oxo-1,2-dihydro­pyrimidin-3-ium cations with both N atoms protonated and the O atom unprotonated, and a complex trinuclear [Cd3Cl11]5− anion of approximately D 3h symmetry, which has a triangle of three octa­hedrally coordinated CdII centres bonded to 11 chloride ions. Three of the chloride ions bridge adjacent Cd atoms, two cap the faces of the Cd3 triangle and the remaining six are terminally bonded and act as hydrogen-bond acceptors. Various N—HCl hydrogen bonds connect the anions and cations and, in addition, inter­molecular N—HO hydrogen bonds contribute to the formation of a three-dimensional network.