The complexes with end-to-end dicyanamide bridges: syntheses, characterization and crystal structures of [Cu(μ 1,5-dca) 2(phen)] n and [Cd(μ 1,5-dca) 2(py) 2] n (phen=phenanthroline; py=pyridine; dca=dicyanamide, N(CN) 2 −)

Abstract

Two new dicyanamide (dicyanamide=[N(CN) 2] −, dca) bridged complexes, [Cu(μ 1,5-dca) 2(phen)] n ( 1) and [Cd(μ 1,5-dca) 2(py) 2] n ( 2) have been synthesized and their structures have been determined by X-ray crystallography diffraction. Complex 1 crystallizes in the monoclinic space group P2(1)/ c with a=10.1502(3), b=10.9815(4), c=14.5839(4) Å and Z=4. The adjacent copper atoms are connected by single end-to-end dca bridges to form a chain structure along the b axis. The chains are linked via Cu⋯N weak interactions to give rise to a 2D layer structure, which furthermore into a 3D structure by the π–π interaction between aromatic rings of adjacent layers. Complex 2 crystallizes in the monoclinic space group C2/ m with a=6.6849(10), b=17.476(2), c=13.231(2) Å and Z=4. The cadmium(II) center is six-coordinated with a distorted octahedral geometry, bounded to four N atoms of four dca ligands and two N atoms of two-chelated py ligands. Neighbor Cd(II) atoms are linked by the double end-to-end dca bridges to generate a chain structure, which result in a 2D layer structure through the π–π interactions between the adjacent chains with distances 3.641 Å. EPR and magnetic results of 1 suggest that the complex exhibits a weak ferromagnetic interaction through CuN C NCNCu pathways.