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 Cu 2+ and Ni 2+ to form binuclear species. The crystal structure of the [Ni 2 (1a)](ClO 4 ) 4 ‚2CH 3 CN complex has been determined by single-crystal X-ray analysis. C 18 H 30 N 4 Ni(ClO 4 ) 2 ‚CH 3 CN crystallizes in the triclinic space group P1 h with unit cell dimensions of a ) 10.716 (3) Å, b ) 12.805(4) Å, c ) 9.292(3) Å, R ) 95.82(2)°, β ) 103.06(2)°, γ ) 94.94(2)°, and V ) 1227.8 Å 3 , Z ) 2, 2396 observations, and R(F) ) 0.036. The cationic part of the complex is a dimer lying on a crystallographic inversion center. Each metal ion is coordinated to four nitrogen atoms of a cyclam unit giving an approximatively square planar coordination geometry, with an intermetallic distance of 6.830(1) Å. The ESR spectra of the binuclear Cu 2+ complexes clearly show metalmetal cooperative interactions.
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