Preparation and crystal structure of the oxalato-bridged Cr III –Ag I two-dimensional compound {Ag 3 (H 2 O)[Cr(dpa)(ox) 2 ] 3 } n ·2nH 2 O (dpa = 2,2′-dipyridylamine)

The reaction of the mononuclear complex [Cr(dpa)(ox)2]− (dpa = 2,2-dipyridylamine) with Ag+ in aqueous solution affords the two-dimensional compound {Ag3(H2O)[Cr(dpa)(ox)2]3}n·2nH2O (1) whose structure has been determined by single-crystal X-ray diffraction. Six crystallographically independent metal atoms (three chromium and three silver atoms) occur in 1. The three [Cr(dpa)(ox)2]− units in 1 act as ligands towards the silver atoms through the two oxalate groups. Each oxalate group acts as bridging ligand adopting five coordination modes: bis-bidentate, bis-bidentate/monodentate (outer), bis-bidentate/monodentate (inner), bidentate/bis-monodentate (outer) and bidentate/monodentate (outer). The use of the [Cr(AA)(ox)2]− (AA = bidentate nitrogen donor) building block in the design of heterometallic species of different dimensionalities is discussed in the light of the available structural results.