Self-assembly of five cadmium(II) coordination polymers from 4,4′-diaminodiphenylmethane

Five cadmium(II) coordination polymers formed from dadpm idadpm 4,4'-diaminodiphenylmethane), namely, [Cd(dadpm)(I)(2)](n) (1), [{Cd(dadpm)(2)(Cl)}(dca)](n) (2) [dca = dicyanamide anion, N(CN)(2)(-)], [{Cd(dadpm)(2)(Br)}(dca)], (3), [Cd(dadpm)(SCN)(2)](n) (4) and [Cd(dadpm)(dca)(2)](n) (5) have been synthesized and characterized by NMR, IR, and fluorescence spectroscopy as well as TG analysis. The ligand dadpm in 1 bridges the metal centers to form a zigzag chain where the halide anion 1- acts as a terminal ligand. Weak Cd...I interactions between adjacent chains extend the zigzag chains into a wave-Like layer. Complexes 2 and 3 are isomorphous, the metal centers are bridged by dadpm to generate a double-stranded chain containing the metalla-cycles of [Cd-2(dadpm)(2)], and the halide anions (Cl- in 2 and Br- in 3D link adjacent chains into 2D layer structures in a trans mode. Dicyanamide anions in the two complexes lie between the layers as supported anions and link the adjacent layers into 3D structures through hydrogen bonds. In complex 4, the metal centers are bonded by the thiocyanate anions to form double-stranded chains, which are linked by dadpm in different orientations resulting in a cross-linked 3D structure. In 5, dicyanamide anions connect the cadmium(n) centers to form a [Cd(dca)2]. 2D layer, which contains 24-membered ring units [Cd-4(mu(1,1)-dca-N,N)(4)]. The dadpm ligand links the adjacent layers into an alpha-Po-like 3D network structure. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).