A metastable 3D supramolecular compound [Ag(NH3)(2)]-[Ag-3(pzdca)(2)(NH3)(4)] (H(2)pzdca = pyrazine-2,3-dicarboxylic acid) (1) has been synthesized and characterized crystallographically. This study offers important information to in-depth understanding of the self-assembly process involving Ag-1 under ammoniacal conditions and conforms that [Ag(NH3)(2)](+)-containing compounds are the intermediates during synthesis of some Ag-1 coordination polymers.