Framework coordination chemistry; generalised entry into a new class of supramolecular compounds exemplified by the structures of [Mn 2 (ebpy) 3 (NO 3 ) 4 ] n [where ebpy =N,N′-ethylenebis(2-pyridone)] and [Er 2 (ebpyrr) 3 (NO 3 ) 6 ] n [where ebpyrr =N,N′-ethyienebis(2-pyrrolidone)]

The ethylene-bridged bis(2-pyridone) ligand N,N′-ethylenebis(2-pyridone) and its bis(2-pyrrolidone) analogue react with manganese(II) nitrate and erbium(III) nitrate to form polymers containing 36-membered or 54-membered metallomacrocyclic rings, respectively; the 36-membered rings are linked to form a chain polymer and the 54-membered form contiguous two-dimensional sheets.