Synthesis of New Binucleating Cylindrical Macrotricyclic Ligands Where Two Cyclam Rings Are in a Face-to-Face Conformation. Characterization of Their Dicopper(II) and Dinickel(II) Complexes

Abstract

Synthesis of new symmetrical cylindrical macrotricyclic ligands 1a,b, where two cyclam subunits are linked through nitrogen atoms by two aromatic chains of various lengths (meta-xylylenyl, para-xylylenyl) has been achieved. These compounds have been prepared according a five step procedure. The readily available trisheteroprotected cyclam 4 has been reacted with the appropriate bis(bromomethyl)benzene to give the bimacrocycle intermediates 5a,b. The selective deprotection of the tert-butyloxycarbonyl group leads to the diamine bimacrocycles 6a,b. Condensation of these diamines with the appropriate diacid dichloride under high-dilution conditions yields the diamide macrotricycles 7a,b in a significant yield. After reduction of the amide moieties and deprotection of the tosyl groups, new cylindrical macrotricycles 1a,b were obtained. Macrotricyclic ligands 1a,b coordinate Cu2+ and Ni2+ to form binuclear species. The crystal structure of the [Ni2(1a)](ClO4)4·2CH3CN complex has been determined by single-cryst...