A macrocyclic tetradentate ligand containing tertiary amine and pyridine functional groups. Electrochemical and X-ray structural studies on [CoII(CR-Me3)Cl]ClO4 (CR-Me3 = meso-2,3,7,11,12-pentamethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17), 13,15-triene)

Abstract

The new ligand CR-Me3, meso-2,3,7,11,12-pentamethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17), 13,15-triene, has been prepared by methylation of CR-H (CR-H = meso-2,12-dimethyl-3,7,11,17-tetraazabicyclo[11.3.1]heptadeca-1(17),13,15- triene) with formic acid and formaldehyde. The reaction of CoCl2 with CR-Me3 in methanol yielded [CoII(CR-Me3)Cl]+, which was isolated as the perchlorate. A solution of this salt in acetonitrile yielded a reversible Co(III)/Co(II) couple at 0.69 V vs. the Cp2Fe+/0 couple. The high-spin (μeff = 4.8 μB) and air-stable [CoII(CR-Me3)Cl]ClO4 complex crystallizes in space group P21/n, with a = 9.392 (2) Å, b = 17.696 (5) Å, c = 14.189 (4) Å, β = 107.36 (2)°, and Z = 4. X-ray structural analysis (RF = 0.048 for 3316 observed Mo Kα data) showed that the macrocyclic cation conforms closely to idealized Cs molecular symmetry. The coordination geometry about the Co(II) atom is distorted tetragonal pyramidal, with one tertiary amino N atom at the apex and the metal center located 0.41 Å above the basal plane comprising the chloro ligand, the pyridyl N, and the remaining two tertiary amino N atoms. © 1986 American Chemical Society.