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

Abstract

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 L2X 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.