Template synthesis f a tetraazamacrocyclic ligand with two pendant pyridinyl goups:properties of the isomers of the metal-free ligand and of their first-row transition metal compounds

摘要

The one-step reaction of [Cu(en)_2]~(2+) (en=1,2-diaminoethane) with formaldehyde,ethyl 2-pyridyl acetate,and based produces a mixture of [Cu(s-ppymac)]~(2+) and [Cu(a-pypymac)]~(2+) (s-pypymac=syn-6,13-bis(2-pyridinyl)-1,4,8,11-tetraazacyclotetradecane,a-pypymac=anti-6,13-bis(2--yridinyl)-1,4,8,11-tetraazacyclotetradecane;synto-anti ratio appraoximately 1:9 in low yield (6%).Ion exchange chromatography is used for isomer separation,and the two isomers of the metal-free lignad are obtained by reduction of the copper(II) complexes and subsequent ion exchange chromatography.Crystal structure analyses of the metal-free a-pypymac ligand,of two isomeric copper(II) compounds of a-pypymac and one of s-pypymac,and of the cobalt(III) complexes of a-and s-ppymac and nickel(II),as well as zinc(II) complexes of a-pypymac.are reported and discussed on the basis of the expectations from force field calculations and from published expermental data of the transition metal compounds of the bis-pendant amine dervative diammac.