The preparations are reported of a range of metal complexes of the 'extended reach' ambidentate ligand 1-(4'-pyridyl)pyridin-4-one (pypd), four of which have been shown by X-ray studies to have polymeric network structures. The compound [Cu(pypd) 2 (H 2 O) 4 ](NO 3 ) 2 .4H 2 O (1) forms sheets comprising [Cu(pypd) 2 (H 2 O) 4 ] units linked by a complex set of hydrogen bonds. Crystals of stoichiometry Co(pypd) 2 (NCS) 2 .MeOH.H 2 O (2) contain a 1:1 co-crystallisation of [Co(pypd) 2 (H 2 O) 2 (NCS) 2 ] and [Co(pypd) 2 (MeOH) 2 (NCS) 2 ] each forming hydrogen bonded chains, which are linked into sheets by further hydrogen bonds. A combination of hydrogen bonding and π-π stacking between pyridyl and pyridone rings in Nd(pypd) 2 (H 2 O) 2 (NO 3 ) 3 (3) also generates a sheet structure. The compound [Cd(pypd) 3 ](ClO 4 ) 2 .3H 2 O (4) forms a complex 3D network.