Synthesis and coordinating properties of the functionalized macrocyclic ligand 1,4-bis(1-methylimidazol-2-ylmethyl)-7-carboxymethyl-1,4,7-triazacyclonona ne. Crystal structures of cobalt(III), nickel(II) and zinc(II) complexes

摘要

The synthesis of the new unsymmetrically derivatized macrocycle 1,4-bis(1-methylimidazol-2-ylmethyl)-7-carboxymethyl-1,4,7-triazacyclonona ne (LH) is reported. The potentially hexadentate ligand yields cobalt(III), nickel(II) and zinc(II) complexes of formulae [CoL](PF6)(2) (1), [NiL]PF6 . CH3OH (2) and [ZnL]ClO4 . H2O (3), which have been isolated in the solid state and characterized. The nickel complex is remarkably stable towards ligand dissociation in water solution even in the presence of a large excess of CN-. The structures of the complexes have been determined by single-crystal X-ray analyses. Compound 1 crystallizes in the triclinic space group P (1) over bar, a =7.397(2), b = 10.960(4), c = 17.420(5) Angstrom, alpha = 101.51(3), beta = 91.85(4), gamma = 98.24(3)degrees, Z = 2. Compound 2 is monoclinic P2(1)/a, a = 14.094(15), b = 11.045(4), c = 16.905(5) Angstrom, beta = 105.54(7)degrees, Z = 4; 3 is triclinic P (1) over bar, a = 7.903(4), b = 9.218(5), c = 16.996(10) Angstrom, alpha = 98.51(6), beta = 96.76(8), gamma = 101.98(7)degrees, Z = 2. In each complex cation the metal atom is six-coordinated, being surrounded by the three macrocycle nitrogens, the two imidazole nitrogens and one carboxylate oxygen atom, with a coordination geometry which is approximately trigonal antiprismatic in 1 and 2 and trigonal prismatic in 3. (C) 1998 Elsevier Science S.A. All rights reserved. [References: 19]