Interligand π,π-stacking interactions giving a bi-layered 2D framework in the crystal of poly-{(N4′-2,4′-bipyridine)-μ-(N,O,O′,O″-iminodiacetato)copper(II) hydrate}, {[Cu(IDA)(2,4′-bipy)]·H2O}n

The stoichiometric reaction of Cu2CO3(OH)2, iminodiacetic acid [H2IDA=HN(CH2CO2H)2)] and 2,4′-bipyridine (2,4′-bipy) in water yields crystalline samples of {[Cu(IDA)(2,4′-bipy)]·H2O}n. The compound was studied by thermal, spectral (FT-IR and reflectance), magnetic (ESR and susceptibility) and X-ray diffraction methods. The structure was solved and refined to a final R1=0.035. The Cu(II) atom exhibits a type 4 + 1 coordination and 2,4′-bipy ligand links the metal by its N4-donor. IDA exhibits a mer-tridentate chelating role and uses a syn-anti-bridging carboxylato group to give polymeric chains extending parallel to the c axis, leaving all 2,4′-bipy ligands towards the same side. Water molecule reinforces the chain stability forming H-bonds with two O(carboxyl) acceptors from adjacent complex units. Both pyridyl rings of 2,4′-bipy are nearly coplanar (1.0(2)°). Adjacent 2,4′-bipy ligands of the same complex chain define an open dihedral angle (69°). 2,4′-bipy ligands belonging to symmetry related chains stack both pyridyl rings at 3.40 Å, thus forming a 2D framework with IDA ligands lying towards both external faces and N-heterocyclic ligands inside. In the crystal N(IDA)-H⋯O(IDA) hydrogen bonds connect up and down adjacent 2D frameworks in a 3D network.