The monomeric form of a cobalt(III) complex of a tetraaza macrocyclic ligand with a dangling carboxylate arm

The monomeric structure of cis-dichloro[3-(1,4,7,10-tetraazacyclododecan-1-yl)toluic acid-kappa(4)N] cobalt(III) chloride monohydrate, [CoCl2(C16H26N4O2)]Cl.H2O, has been determined. Previous work has only yielded crystals of the dinuclear complex or the monomeric complex in powdered form. Crystallization was effected from concentrated hydrochloric acid which contributed to the retention of the chlorides coordinated to the cobalt as well. as providing the chloride counter-anion. Hydrogen bonding of the hydroxyl group of the carboxylic acid function to the chloride counter-anion played a significant role in the formation of crystals of this species.