THE 1ST GOLD(III) MACROCYCLIC POLYAMINE COMPLEXES AND APPLICATION TO SELECTIVE GOLD(III) UPTAKE

The hitherto unreported gold(III) macrocyclic polyamine complexes 12, 14, 18, 19, 23, and 24 with cyclam (1,4,8,11-tetraazacyclotetradecane, 1), phenol-pendant cyclam 2, pyridyl-pendant cyclam 3, monooxocyclam 4, phenol-pendant monooxocyclam 5, and pyridyl-pendant monooxocyclam 6 have been synthesized and characterized. Dissociation of a proton from one of the secondary amines in the "Au(III)-in" cyclam complexes 12, 14, and 18 readily occurs with pK(a) values of 5.0-5.4 at 25-degrees-C and I = 0.1 (NaClO4). Although monooxocyclam 4 does not accommodate Au(III), the donor-pendant monoxocyclams 5 and 6 enclose Au(III) with concomitant dissociation of an amide proton to yield 23 and 24, respectively. As anticipated for the diamagnetic d8 complexes, the pendant donors only weakly interact from an axial site. The extraordinary acidity of Au(III) over other common metal ions in interaction with cyclam can be utilized for selective uptake of Au(III) with lipophilic cyclam derivatives 9 and 10.