Conserved supramolecular architecture in polymetallic nucleobase complexes

The single crystal X-ray structures of two different polynuclear metal-nucleobase complexes are reported. Crystals isolated from the reaction of CdBr2 with ethylenediamine-N9-ethyladenine, A-Et-en, were characterised by X-ray structural analysis as a coordination polymer [mu-{CdBr(N3,N7-A-Et-en)}(2)CdBr4] (2). Reaction of the Pd(II)-adenine complex, [PdCl(N3-A-Et-en)](+), with sodium uracilate yielded [(Pd(N3-A-Et-en)(2)(N1,N3-U)][ClO4](2) (3). Despite the considerable differences in the nature of the compounds the crystal structures feature essentially similar supramolecular architectures. A building block analysis demonstrates how this arises and reveals an approach, based on bond-type substitution and molecular replacement, to conserving such features. This may be a useful approach that could be more widely adopted in crystal engineering strategies. (c) 2006 Elsevier B.V. All rights reserved.