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 [μ-{CdBr(N3,N7-A-Et-en)}2CdBr4] (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.