Crystal structure of dichlorotetra-µ-adenine-dicopper(II) chloride hexahydrate

Abstract

The structure of dichlorotetra-µ-adenine-dicopper(II) chloride hexahydrate, [Cu₂(ade)₄Cl₂]Cl₂,6H₂O, has been determined by three-dimensional X-ray crystal structure analysis. The crystals are orthorhombic with unit-cell dimensions a= 23·92, b= 13·844, c= 11·262 Å, Z= 4, space group Cmca. Full-matrix least-squares refinement, using 870 visually estimated reflections, has reached R 0·098.

The structure contains the complex ion [Cu₂(ade)₄Cl₂]²⁺, chloride ions and molecules of water of solvation. The complex ion, which has 2/m crystallographic symmetry, is dimeric with pairs of copper atoms held together by four bridging adenine ligans, co-ordinated via N(3) and N(9). The copper atoms have a square pyramidal co-ordination, with chlorine in the apical position at a distance of 2·429 Å. The metal is 0·33 Å above the plane of four nitrogen atoms, with Cu–N distances of 2·008 and 2·041 Å. The Cu ⋯ Cu non-bonded separation is 3·066 Å.

The chloride ions together with the water molecules and all non-donor nitrogen atoms of adenine form an intricate network of hydrogen bonds in which linkages of the type O–H ⋯ N, N–H ⋯ O, and O–H ⋯ Cl^– are involved.