Cyclic ligand control of kinetic lability. Kinetics of dissociation of nickel(II) complexes of a series of O2N2-donor macrocycles in acid

Article abstract of DOI:10.1021/ic50205a028

The kinetics of dissociation in acid of a range of nickel complexes of 14-17-membered macrocycles containing an O₂N₂-donor set has been studied. Macrocycle structure was found to strongly influence the observed first-order dissociation rate constants, and, for the unsubstituted macrocycles, the kinetic labilities follow the ring size sequence 14 > 15 > 16 < 17. In accord with this sequence, hole size considerations suggest that the 16-membered macrocycle provides the ring of best fit for nickel in this series of ligands. An observed enhancement of the dissociation rate in the presence of acetate ion relative to the rate in the presence of a number of other ions has also been studied.