Zinc(II) polymeric compounds with a chelating ligand bis(2-pyridylmethyl)amine (bispicam) directed by intermolecular C/N/O–H⋯X (X = Cl, Br, I) interactions: Catalytic activities

[Zn(bispicam)2]2+ as a hydrogen-bond donor and three free halides (Cl−, Br− and I−) as hydrogen-bond acceptors were employed to investigate the role of non-classical C/N–H⋯X hydrogen bonding for construction of polymeric compounds. Three zinc salts (ZnCl2, ZnBr2 and ZnI2) were reacted with bis(2-pyridylmethyl)amine (bispicam) to produce [Zn(bispicam)2]Cl21, [Zn(bispicam)2]Br22 and [Zn(bispicam)2]I23. Hydrogen bonding interactions between Namine–H and C–H of [Zn(bispicam)2]2+ cations and free halides, and between Owater–H and free halides can play very important roles for construction of molecular packing and crystal structures. In addition, these hydrogen-bonded complexes 1, 2 and 3 were, interestingly, shown to carry out the catalytic transesterification of a range of esters with methanol at 50 °C under the mild conditions, though all these compounds are saturated with two bispicam ligands. To explain this unusual reactivity, it has been proposed that the hydrogen atom of amine N–H moiety in the complexes could do the acid-catalyzed transesterification.