Synthesis and crystal structure determination of some asymmetrical and symmetrical CR-type macrocyclic schiff base complexes, with a single pendant coordinating 2-aminoethyl arm

A novel, totally asymmetrical tripodal 2,3',4 " -tetraamine ligand, N{(CH2)(2)NH2}{(CH2)(3)NH2}{(CH2)(4)NH2}, epb, has been synthesized. In the presence of copper(II) and nickel(II) ions it condenses with 2,6-diacetylpyridine in 1:1 ethanol-water solution, producing some new CR-type complexes with a pendant primary amino group. The X-ray crystal structure of the resulting copper(II) complex, [Cu(3,4(2)-CR)](PF6)(2) (1), and two other related complexes, [Cu(2,4(2)-CR)] (ClO4)(2) (2) and [Cu(3,3(2)-CR)](ClO4)(2) (3), are reported. Crystal data: complex 1, monoclinic, P2(1)/n, a 8.366(3) Angstrom, b = 15.549(3) Angstrom, c = 20.283(2) Angstrom, beta = 98.73(2)degrees, V = 2607.8(11) Angstrom (3), Z = 4, R1 = 0.0621, wR2 = 0.1615; complex 2, monoclinic, P2(1)/c, a = 7.981(10) Angstrom, b = 18.882(3) Angstrom, c = 15.185(3) Angstrom, beta = 96.40(2)degrees, V= 2275.7(6) Angstrom (3), Z = 4, R1 = 0.0773, wR2 = 0.1635; complex 3, monoclinic, P2(1)/n, a 7.8764(10) Angstrom, b = 15.361(2) Angstrom, c = 19.370(2) Angstrom, beta = 100.330(10)degrees, V= 2305.7(5) Angstrom (3), Z = 4, R1 = 0.0537, wR2 = 0.1397. In all of these, copper atoms are bonded to four nitrogens of a macrocyclic ring and a nitrogen of the pendant arm. The arrangements are slightly distorted square-pyramidal in which the primary amino groups occupy apical positions and have the longest Cu-N distances. For all isomers, copper(II) ions are somewhat above the plane of the imino-pyridine system of the macrocyclic ring in the direction of the pendant coordinated primary amino group.