[{Fe(tim)}2]: an Fe-Fe dimer containing an unsupported metal-metal bond and redox-active N4 macrocyclic ligands.

Mixed doubles: The dimeric complex [{Fe(tim)}(2)] (see structure, tim = 2,3,9,10-tetramethyl-1,4,8,11-tetraazacyclotetradeca-1,3,8,10-tetraene) represents an unprecedented complex containing an unsupported Fe-Fe bond. The crystal structure confirms the presence of reduced tim units, thus indicating ligand redox activity. Spectroscopic and computational studies establish a triplet ground state for [{Fe(tim)}(2)] and suggest a mixed-valence compound with respect to both the Fe ions and the ligands.