Anion mediated diversity in the H-bonded assembly of a series of heteronuclear copper(II)/sodium(I) compounds

Three heteronuclear Cu(II)/Na(I) compounds, [Cu(vanpn)Na(NO3)(H2O)] (1), [Cu(vanpn)Na(N3)(CH3OH)] (2) and [Cu(vanpn)Na(NCS)(H2O)] (3) where H2vanpn = N,N′-(1,3-propylene)-bis(3-methoxysalicylideneimine), a well known compartmental Schiff base ligand, have been prepared and characterized by elemental analysis, IR and UV–Vis spectroscopy and single crystal X-ray diffraction studies. Compound 1 crystallises in monoclinic space group P21/n, compound 2 in triclinic P 1 ¯ and compound 3 in orthorhombic space group Pbca. In all the compounds, Cu atoms assume distorted square planar geometries whereas Na atoms exhibit distorted octahedral geometry. In compound 1, the nitrate ion is coordinated as a chelating ligand and essentially both the O atoms of the nitrate occupy one axial site. Variation of the counter anions leads to considerable change in the H-bonded supramolecular structures of the compounds. Compound 1 forms a dimer, compound 2 constitutes a chain and compound 3 forms a helix. Electrochemical electron transfer study reveals Cu(II)Cu(I) reduction in acetonitrile solution.