Synthesis of 6-amino-6-(4-aminobenzyl)-1,4,8,11-tetra-azacyclotetradecane,a new pentadentate polyamine ligand, and crystal structure of its Co(III) complex

The facile synthesis of the hydrochloride salt of the 6-amino-6-(4-aminoben zyl)-1,4,8,11-tetra-azacyclotetradecane L-3 is reported. The Co(III) comple x of this new pentadentate ligand crystallizes in the space group P2(1)/n, with a=15.5901(3), b = 8.9267(2), c = 20.6011(4) Angstrom, beta = 100.5960( 10)degrees X-ray crystal structure analysis has shown the 6-amino group axi ally coordinated to the metal center, and the cyclam moiety taking a trans I configuration. Water coordinates at the sixth site. The axial Co-N distan ce is 1.935(3) Angstrom, and the cyclam core nitrogen-Co distances are in t he range between 1.957(3) and 1.964(3) Angstrom, shorter than previously re ported data for similar macrocyclic complexes. The crystal structure of the complex [Cu(L-2)(NO3)(2)] (L-2: 6-nitro-6-(4-nitrobenzyl)-1,4,8,11-tetraaz acyclotetradecane), synthetic precursor to the Li ligand is also reported. It crystallizes in the space group P2(1)/n, with a = 19.49560(10), b = 8.38 520(10), c = 15.8518(2) Angstrom, beta = 111.03 degrees. (C) 1999 Elsevier Science S.A. All rights reserved.