Bicyclam [6,6'-bi(1,4,8,11-tetra-azacyclotetradecane)]: a ditopic receptor for homo- and hetero-bimetallic complexes

Bicyclam, 6,6'-bi(1,4,8,11-tetraazacyclotetradecane) (L), was prepd. by reducing 6,6'-bi(1,4,8,11-tetraazacyclotetradecan-5,7-dione) with B2H6 in (MeOCH2)2O. [M2L]4+ (M2 = Cu2, Ni2, CuNi) were prepd. and characterized by analyses, visible and ESR spectra, magnetic moments, and electrochem. Whereas the visible spectra of [M2L]4+ are similar to those of the mononuclear complexes with cyclam, electrochem. indicates a weak interaction between the metal ions coordinated by bicyclam, as shown by a shift of the 2nd oxidn. potential M2+ → M3+ to move pos. values.