Syntheses, characterizations and structures of complexes of the types mononuclear [MII(tren)(dca)]ClO4 [M = Cu and Zn; tren = tris(2-aminoethyl)amine; dca = dicyanamide] and dinuclear [CdII2(tren)2(dca)](ClO4)3: Variation of nuclearities and architectures

Two mononuclear [Cu(tren)(dca)]ClO4 (1) and [Zn(tren)(dca)]ClO4 (2) and one dinuclear [Cd2(tren)2(dca)](ClO4)3 (3) [tren = tris(2-aminoethyl)amine; dca = dicyanamide] compounds have been synthesized and characterized using spectroscopic, magnetic and X-ray crystallographic results. Complexes 1 and 2 adopt trigonal bipyramidal geometry with MN5 (M = Cu, Zn) chromophores coordinated through four N atoms of tren and one nitrile N atom of dca. In dinuclear 3, each pentacoordinated cadmium(II) center is in trigonal bipyramidal environment with a CdN5 chromophore coordinated once again by four N atoms of tren and the fifth position of each metal center is occupied by μ1,5 bridged dicyanamide. In the long-range form, complexed cations and counter anions in 1 are engaged in N–H···O, N–H···N and C–H···O hydrogen bondings resulting in a 2D sheet structure parallel to the ac-plane, and in 2 these hydrogen bonds are coupled with C–H···N hydrogen bond leading to a 3D network structure. In 3, cooperative N–H···O and C–H···O hydrogen bonds are seen affording a 3D continuum.

Graphical abstractDesign, synthesis and X-ray-structures of three polycrystalline metal organic frameworks containing bifunctional ligand tris(2-aminoethyl)amine and larger-sized molecular ion rod, dicyanamide are described. Variation of nuclearities, and varitable molecular and crystalline architectures formed by different kinds of N–H···N, N–H···O, C–H···N and C–H···O hydrogen bonds by varying metal-ion templates have been discussed.Figure optionsDownload full-size imageDownload as PowerPoint slide