Synthesis and structural characterisation of a series of cobalt complexes of N-appended anthracenyl cyclam

The synthesis and structural characterisation of a series of cobalt complexes of 1-(anthracen-9-ylmethyl)-1,4,8,11-tetraazacyclotetradecane (hereafter L2 ) is described. The complexes, of the type trans -[Co L2 X 2 ] + in which X = Cl − , NCS − and NO 2 - were synthesised for their use in photoactivated ligand release studies. X-ray crystal structures show that the macrocycle in all three complexes of the series adopts a trans-(III) configuration. Both thiocyanato ligands were found to be N-bound in trans -[Co L2 (NCS) 2 ] + while trans -[Co L2 (NO 2 ) 2 ] + contained both a nitro and nitrito ligand in the one complex. The synthesis of the complex cis -[Co L2 (NO 2 ) 2 ] + from sodium hexanitrocobaltate(III) is also described. This complex also contains both a nitro and nitrito ligand in the one complex, with the cyclam in a cis-(V) arrangement about the metal centre.