The interplay of hydrogen-bonding and metal-coordination motifs in the formation of supramolecular patterns: Copper/zinc malonates-aminopyrimidine complexes

The X-ray crystal structures of 1 [2[AMPYH]center dot[(Cu (H2O) (mal)(2))]:2H(2)O] and 2 [2[AMPYH]center dot[ZnBr (Hmal) (mal)]:2H(2)O] [mal = malonate; Hmal = hydrogen malonate; AMPYH = 2-amino-4, 6-dimethylpyrimidinium] reveal the interplay of metal-coordination motifs and the hydrogen-bonding patterns. In both the structures, the 2-amino-4,6-dimethylpyrimidine cations are not directly coordinated to copper and zinc, but are hydrogen-bonded to the malonate ion. The protonated endocyclic nitrogen and the amino group of 2-amino-4.6-dimethylpyrimidine molecule interact with malonate ligand via a pair of N-H center dot center dot center dot O hydrogen-bonds, (with graph set notation R-2(2)(8)) whereas the unprotonated endocyclic nitrogen and the amino group interact with the malonate ligand via N-H..O and C-H center dot center dot center dot N hydrogen-bonds forming the same R-2(2)(8) motif. The combination of hydrogen-bonding motif and metal-coordination motif creates a novel supramolecular motif. The interplay of the hydrogen-bonding motif and metal-coordination motif via hydrogen-bonds leads to similar supramolecular motifs in both the structures. (C) 2006 Elsevier B.V. All rights reserved.