Bonds and lone pairs in the flexible coordination sphere of lead(II)

The single crystal XRD characterisation of a 'mixed anion' complex of Pb(II) with 1,10-phenanthroline, [Pb(phen)(O2CCH3)(O2ClO2)], shows the complex to be polymeric as a result of acetate ligand bridging, the Pb atom being in an unsymmetrical eight-coordinate, N2O6, environment and the crystal array reflecting a strong influence of pi-pi stacking of the heteroaromatic chelate ligands. The structure is used to raise issues concerning the coordination sphere of lead(II) which are of relevance to the rational design of solid state arrays.