Studies of pendant arm macrocyclic ligands. Part 6. Synthesis of two penta-aza macrocyclic ligands containing single pendant co-ordinating 2-pyridylmethyl and 1-pyrazolylmethyl arms, and characterisation of their nickel(II), copper(II), cobalt(II), and zinc(II) complexes. Crystal structure of {3,11-dibenzyl-7-(2′-pyridylmethyl)-3,7,11,17-tetra-azabicyclo[11.3.1]-heptadeca-1(17),13,15-triene}zinc(II) perchlorate
Abstract
Reaction of the secondary amine group of 3,11-dibenzyl-3,7,11,17-tetrazabicyclo[11.3.1]heptadeca-1(17),13,15-triene (L2) with 2-chloromethylpyridine in the presence of base, or with 1-(hydroxymethyl)pyrazole, gives two new pendant-arm macrocycles, L3 and L4, having 7-(2′-pyridylmethyl) and 7-(1′-pyrazolylmethyl) groups, respectively. Complexes of Co2+, Ni2+, Cu2+, and Zn2+ with L3 and L4 have been isolated and characterised. The structure of [Zn(L3)][ClO4]2 has been established by X-ray crystallography, and confirms solution 1H n.m.r. studies; the two benzyl groups and the pendant arm lie on the same side of the macrocycle. Protondecoupled 13C n.m.r. spectra of the Zn2+ complexes of L3 and L4 show the presence of only a single symmetric isomer in each case. In the [Zn(L4)(dmso)]2+ ion, the presence of a strongly co-ordinated dimethyl sulphoxide (dmso) molecule is confirmed both in the solid state and in solution, and solid complexes of formula [M(L)(dmso)][ClO4]2(L = L3 or L4; M = Co, Ni, or Cu) have been prepared in all cases.
Please wait while we load your content...
