Kinetic study of base-catalyzed asymmetric nitrogen conversion of cis-folded macrocyclic nickel(II) complex of 1,4,7,11-tetraazacyclotetradecane

The kinetics of the cis-to-planar interconversion of cis-[Ni(1,4,7,11-tetraazacyclotetradecane)(H2O)2]2+ in basic aqueous solution has been examined spectrophotometrically. All kinetic data are satisfactorily fitted by the rate law R = (k1KOH[OH−]2 + k2[OH−])(1 + KOH[OH−])−1(cis-[Ni(isocyclam)(H2O)2]2+ + [Ni(isocyclam)(OH)]+). A free-base-catalyzed mechanism is given for this reaction in which nitrogen inversion, solvation and ring conformational changes occur.