Reaction of Mn(ClO4)(2) or Co(PF6)(2) with 4,4'-dipyridine-dioxide (dpdo) produced novel molecular species [M(dpdo)(4)(H2O)(2)](2+), which hold a tetrahedral configuration notwithstanding their octahedral environment around the metal centers. The tetrahedral moieties are further assembled through hydrogen bonds between peripheral NO ends of dpdo ligands and coordinated water molecules, giving rise to 3D diamondoid networks.