Two formate-bridging coordination polymers containing dinuclear zinc(II) macrocyclic components

Two coordination polymers (2a and 2b) containing dinuclear zinc(II) macrocyclic components have been unexpectedly obtained when pyrazine and 2-methylpyrazine were used to react with dinuclear zinc(II) macrocyclic complexes la and 1b, respectively. The X-ray crystal structural study indicated that the coordination environment around each Zn(II) atom in 2 is a five-coordinated distorted pyramid in which the apical position is occupied by a bridging formate anion, unlocalized in an end to end fashion. The formate group acts as a bidentate bridging ligand to link two adjacent macrocyclic units forming a chain polymer. In addition, H-bonding interactions are observed in the crystal packing of 2a and 2b, which could be described as two-dimensional networks. (C) 2002 Elsevier Science B.V. All rights reserved.