The reaction of A2CO3 (A = Rb, Cs) with elemental sulfur and silver in supercritical ethylenediamine results in formation of RbAg5S3 and CsAg7S4, respectively, in nearly 50% yield. Both compounds contain a complex silver sulfide framework structure made of formal Ag+ and S2- building blocks. There are no S-S bonds, but there are several short Ag-Ag distances, which may be due to some metal-metal interactions. The structures contain infinite open channels between the silver sulfide superstructures, which contain the alkali metal cations. The channels are fairly wide (over 6 angstrom across) and suggest the possibility that microporous solids may be prepared using this methodology.