COBALT(3) COMPLEXES OF MACROCYCLE MESO-2,12-DIMETHYL-3,7,11,17-TETRAAZABICYCLO[11.3.1]HEPTADECA-1(17),13,15-TRIENE

Cobalt(III) complexes of a tetradentate macrocyclic ligand meso-CRH. with the general formula [Co(CRH)XY] (ClO4)n have been prepared and characterized (XY = (Cl-)2, (Br-)2, (I-Cl-), (H2O)2, (OH-)2, (N3-Cl-), (N3-)2, (NCS-)2, (CN-)2, (NO2-)2, CO32-, C2O42-, acac-, and en). The cyclic ligand contains one pyridine nitrogen and three secondary amine nitrogens as its donor groups. The macrocycle can coordinate with all of its donor groups in one plane or in a folded form. This leads to the formation of geometrical (cis-trans) isomers. Both geometrical isomers can exist as configurational isomers because of the asymmetric tetrahedral nitrogens. In the case of the dichloro complexes two trans-configurational isomers (α and β) and one cis (β) isomer have been isolated, and their structures are tentatively assigned on the basis of theoretical considerations and chemical and physical studies. The conformations of saturated six-membered chelate rings are discussed in general terms. © 1969, American Chemical Society. All rights reserved.