Spontaneous assembly of a nine-vertex lithium framework encapsulating the peroxide dianion

AInvestigation of the structure of the lithiated bicyclic guanidine 1,3,4,6,7,8-hexahydro-2H-pyrimido[1,2-a]pyrimidine (hppH) has led to the reproducible isolation of compounds containing the ʹLi9(hpp)7(O2)ʹ core, in which a peroxide dianion has been encapsulated within a mono-capped, cubic array of lithium ions.