MACROCYCLIC LIGAND RING SIZE EFFECTS .2. SYNTHETIC, STRUCTURAL AND ELECTROCHEMICAL STUDIES OF THE INTERACTION OF NI-2 WITH 14-MEMBERED TETRAAZA MACROCYCLES CONTAINING FUSED DIBENZO SUBSTITUENTS

A comparative study of the high- and low-spin complexes of Ni(II) with two tetraaza dibenzo-substituted macrocycles incorporating 14-membered inner rings has been carried out. The results obtained are also compared with those for the analogous nickel(II) derivatives of 1,4,8,11-tetraazacyclotetradecane. Four X-ray structures of nickel complexes as well as the structure of one free ligand have been determined. These structures taken together with previous X-ray structural data and selected molecular mechanics calculations have enabled a detailed assessment of the effects of spin state and ligand substituent on the hole size and ring conformations adopted by individual complexes. A comparative electrochemical investigation of individual high- and low-spin complexes in the series has been performed.