Copper(II), iron(III) and cobalt(III) complexes of the pendent-arm cyclam derivative 6,6,13-trimethyl-13-amino-1,4,8,11-tetraazacyclotetradecane

The interaction of Cu(II), Fe(III) and Co(III) with 6,6,13-trimethyl-13-amino-1,4,8,11-tetraazacyclotetradecane ( L 3 ) incorporating a pendent amine group has led to isolation of the new octahedral complexes [Cu(H L 3 )(ClO 4 ) 2 ]Cl·H 2 O ( 1 ), [Fe( L 3 )Cl](S 2 O 6 )·H 2 O ( 2 ), [Co( L 3 )Cl](ClO 4 ) 1.5 Cl 0.5 ·0.25H 2 O ( 3 ), [Co(H L 3 )Cl 2 ](ClO 4 ) 2 ·H 2 O ( 4 ) and [Co( L 3 )Cl] 2 (S 2 O 4 )(ClO 4 ) 2 ( 5 ). In ( 1 ) the copper ion occupies the macrocyclic cavity of protonated (–NH 3 + ) L 3 which is present in its trans -III configuration; weakly bound ClO 4 − ligands occupy the axial positions. The X-ray structure of ( 2 ) showed that Fe(III) occupies the N 4 -macrocyclic cavity of L 3 in a trans -III configuration, with the pendent amine group binding in an axial position. The remaining axial position is occupied by a Cl − ligand. Chromatography of the product obtained from the reaction of Na 3 [Co(CO 3 ) 3 ] with L 3 yielded three fractions. Fraction 1 yielded crystals ( 3 ) composed of three crystallographically independent species incorporating cations of type [Co( L 3 )Cl] 2+ with very similar structures; in each case the macrocyclic ring nitrogens of L 3 are bound to the Co(III) in an asymmetric cis -fashion. Fraction 2 yielded the trans -III octahedral cationic complex ( 4 ) incorporating L 3 in its protonated form. The Co(III) complex ( 5 ) from fraction 3 shows a different coordination arrangement to the products from fractions 1 or 2. The macrocyclic ring coordinates in its trans -III form, but the axial sites in this case are occupied by the pendent-NH 2 group and a Cl − ligand.