Networks with hexagonal circuits in co-ordination polymers of metal ions (ZnII, CdII) with 1,1′-(1,4-butanediyl)bis(imidazole)

Abstract

Three new compounds, [ZnL_1.5(H₂O)(SO₄)]·6H₂O 1, [ZnL_1.5(H₂O)₂][NO₃]₂·2H₂O 2 and [CdL_1.5(H₂O)₂(SO₄)]·4H₂O 3 were obtained from self-assembly of the corresponding metal salts with 1,1′-(1,4-butanediyl)bis(imidazole) (L). In both 1 and 2 zinc ion is five-co-ordinated, showing a less-common trigonal bipyramidal co-ordination polyhedron, while cadmium ion of 3 is six-co-ordinated with a common octahedral arrangement. The sulfate ions of 1 and 3 are co-ordinated, however the nitrate ions of 2 are not. Each of the three compounds is composed of a (6, 3) network with the hexagonal smallest circuit containing six metal ions and six L; each L is co-ordinated to two metal ions, acting as a bridging ligand. In 1 the 2-D sheet of (6, 3) networks is interpenetrated in an inclined mode by symmetry related, identical sheets to give an interlocked 3-D structure, while the (6, 3) networks of both 2 and 3 stack in a parallel fashion to construct frameworks having channels.