A unique example of a three component cocrystal of metal complexes

The synthesis, characterization and structure of a [3 x 1 + 2 x 1 + 1 x 2] cocrystal [((NiL1)-L-II)(2)Na-I(NO3)]center dot[{(NiLNaI)-L-II-Na-1(H2O)(2)}{(NiL1)-L-II}(2)(NO3)] derived from the hexadentate Schiff base compartmental ligand N,N'-ethylenebis(3-ethoxysalicylaldimine) (H2L1) are described. The compound crystallizes in the monoclinic system (space group C2/c). The structure consists of one trinuclear double-decker [((NiL1)-L-II)(2)Na-I](+) cation, one dinuclear [(NiLNaI)-L-II-Na-1(H2O)(2)](+) cation and two mononuclear [(NiL1)-L-II] moieties. Each of the two coordinated water molecules of the dinuclear unit is encapsulated in the O-4 cavities of the two mononuclear [(NiL1)-L-II] moieties resulting in the formation of a tetranuclear self-assembly, which is further interlinked with the trinuclear sandwich species due to Ni center dot center dot center dot Ni interaction to result in an overall one-dimensional topology in the title compound. A unique example of a three component cocrystal of metal complexes, existence of Na-I in two entirely different environments in spite of being surrounded by the same blocking ligand and structural resemblance of sodium(I) with 3d metal ions are the major outcomes of the present investigation.