The reaction of cis-bisglycinatocopper(II) monohydrate in hydrogen peroxide with 1,4-diaminobenzene gives N-N-bonded oligomer I. Oligomer I contains a free radical with an ESR signal at 3180 G. The oligomer also contains copper(II) ion, with a strong ESR absorption at 3165 G. The oligomer has the property of a thermoelectric switch. A similar oligomerisation reaction of 1,4-diaminobenzene with Co(DAM)(7)Cl-4 (where DAM is diacetylmonoxime) also gives an N-N-bonded oligomer which also has a radical. This oligomer also has the property of a thermoelectric switch.