Synthesis and Crystal Structure Determination of Some Asymmetrical and Symmetrical CR-Type Macrocyclic Schiff Base Complexes, with a Single Pendant Coordinating 2-Aminoethyl Arm

Abstract

A novel, totally asymmetrical tripodal 2,3',4"-tetraamine ligand, N((CH2)2NH2)((CH2)3NH2)((CH2)4NH2), 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) A, b = 15.549(3) A, c = 20.283(2) A, beta = 98.73(2) degrees, V = 2607.8(11) A3, Z = 4, R1 = 0.0621, wR2 = 0.1615; complex 2, monoclinic, P2(1)/c, a = 7.981(10) A, b = 18.882(3) A, c = 15.185(3) A, beta = 96.40(2) degrees, V = 2275.7(6) A3, Z = 4, R1 = 0.0773, wR2 = 0.1635; complex 3, monoclinic, P2(1)/n, a = 7.8764(10) A, b = 15.361(2) A, c = 19.370(2) A, beta = 100.330(10) degrees, V = 2305.7(5) A3, 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 macrocylic ring in the direction of the pendant coordinated primary amino group.

Chiral and Achiral Macrocyclic Copper(II) Complexes: Synthesis, Characterization, and Comparative Binding Studies with Calf-Thymus DNA

“…However, IR spectra of complexes 3 and 4 revealed a very broad band at ca. 3200 cm À 1 [21], which rendered the individual assignment of ñ (NÀH) of ligand and macrocyclic moiety difficult. Far-IR spectra of the complexes exhibited absorptions at 480 -482 cm À 1 and 530 -536 cm À 1 attributed to ñ (MÀO) and ñ (MÀN) bands, respectively, which further confirmed the bonding through the O-atom of the ligand to the metal ion in the chiral macrocyclic complexes [22].…”

Chemoselective N-Nitrosation of Secondary Amines under Mild and Heterogeneous Conditions

“…Yields refer to isolated pure products. The nitrosation products were characterized by comparison of their spectral (IR, 1 H-NMR, 13 C-NMR), TLC and physical data with the authentic samples.…”

Synthesis and characterization of Cd(II) macrocyclic schiff base complex with two 2-Aminoethyl pendant arms

“…We have been interested for some time in the design and synthesis of new macrocyclic Schiff base complexes, particularly, in the synthesis of CR-type [18,19]. These complexes are formed mainly from metal ion templated [1+1] cyclocondensation of 2,6-diacetylpyridine and a linear triamine or tripodal tetraamine [20][21][22].…”

“…These complexes are formed mainly from metal ion templated [1+1] cyclocondensation of 2,6-diacetylpyridine and a linear triamine or tripodal tetraamine [20][21][22]. The latter reactions produce tetraaza macrocycles carrying a single 2-aminoethyl pendant arm [19]. We have also produced Cd(II) pentaaza macrocyclic complexes with two 2-aminoethyl pendant arms, using branched hexaamines and 2,6-diacetylpyridine (Scheme 1) [23].…”