ELECTRONIC-STRUCTURE AND REACTIVITY OF DIOXOLENE ADDUCTS OF NICKEL(II) AND COPPER(II) TRIAZAMACROCYCLIC COMPLEXES

Five-coordinate [M(Me3[12]N3)(DTBSQ)]ClO4 and M(Me3[12]N3)(TCCat) complexes (M = Ni, Cu; Me3[12]N3 = 2,4,4-trimethyl-1,5,9-triaz. cyclododec-l-ene; DTBSQ = 3,5-di-tert-butyl-o-semiquinonate; TCCat = 3,4,5,6-tetrachlorocatecholate) were obtained from reaction of [M(Me3[12]N3)0H]2(ClO4)2 with the appropriate catechol. The magnetic interaction in the nickel(II)-semiquinonate complex is antiferromagnetic, and it is ferromagnetic in the corresponding copper(II) derivative. All the isolated complexes have been found to undergo to one-electron redox processes, and the reaction products have been characterized by electronic and EPR spectroscopy. Evidence is presented that oxidation of the dioxolene ligand originates the redox chain M(II)-Cat, M(II)-SQ, M(II)-Q (Cat = 3,5-di-tert-butylcatecholate, M = Ni, Cu; Cat = tetrachlorocatecholate, M = Ni; SQ = semiquinoate; Q = quinone), but it is apparent that the species Cu(I)-TCQ (TCQ = tetrachloro-o-benzoquinone) results from one-electron oxidation of the Cu(II)-TCCat complex. The electronic spectra of all the stable species are reported and assigned. The role of the electronic structure of the adducts in determining the physical properties and the reactivity is discussed. © 1990, American Chemical Society. All rights reserved.