Syntheses and Single-Crystal X-ray Structures of a Series of Monosubstituted cis,cis-1,3,5-Triaminocyclohexane-Based Complexes

Abstract

The four triimine compounds cis,cis-1,3,5-tris[(E)-(X)-benzylideneamino]cyclohexane [X ) H (1); 3-hydroxy (2); 3,5-dimethoxy (3); 4-acetamido (4)] are synthesized by the condensation of cis,cis-1,3,5-triaminocyclohexane with a substituted aromatic aldehyde. Complexation of these ligands with metal salts (1 with Ni, Cu, and Zn salts; 2 and 3 with Cu salts; 4 with a Zn salt) causes a selective hydrolysis reaction producing new monoimine complexes. The resulting complexes are characterized by a combination of infrared spectroscopy, elemental analysis, mass spectrometry and, in the cases of the zinc complexes, 1 H NMR spectroscopy. The structures of all six complexes are confirmed by single-crystal X-ray crystallographic studies.

Copper(II)-cis,cis-1,3,5-triaminocyclohexane complex-promoted hydrolysis of dipeptides: kinetic, speciation and structural studies

“…In each case, the geometry around the copper ion is square pyramidal distorted along the apical Cu-N bond of one of three amino nitrogens of TACH. The apical Cu-N distance is 2.232 (3) [53,54,55]. GlyGly is coordinated through the terminal NH 2 group and the peptide carbonyl oxygen atom from the same glycine residue with a Cu-N4 distance of 2.024(2) Å and a Cu-O(1) distance of 2.037(2) Å .…”

Structural and mechanistic information on the reaction of bicarbonate with Cu(II) and Zn(II) complexes of tris(2-aminoethyl)amine. Identification of intermediate and product species

“…The complexes, [Cu(tren)(H 2 O)](ClO 4 ) 2 and [Zn(tren)-(H 2 O)](ClO 4 ) 2 , were prepared and characterized according to the literature method. 25 NaHCO 3 was obtained from Fluka and NaH 13 CO 3 from Aldrich.…”

“…2. 13 C NMR measurements were performed on a Bruker DPX 300 (300 MHz) NMR spectrometer. The spectra of 25 mM [Zn(tren)(H 2 O)](ClO 4 ) 2 were recorded in the presence of 75 mM NaH 13 CO 3 as a function of pH in the range 5 to 12.…”

“…Labeled {[Zn(tren)] 3 (µ 3 -13 CO 3 )}(ClO 4 ) 4 revealed a single peak at 168.3 ppm in DMSO-d 6 and at 168.5 ppm in D 2 O, respectively, which are in good agreement with that reported for other Zn-CO 3 complexes with square pyramidal structure. 11a,33 Furthermore, 13 C NMR spectra of [Zn(tren)(H 2 O)] 2ϩ in the presence of H 13 CO 3 Ϫ in D 2 O was studied as a function of pH, and the data are listed in Table 1. At low pH, free 13 CO 2 at 127.5 ppm and H 13 CO 3 Ϫ at 163.1 ppm were observed, whereas at high pH, a peak at 170.8 ppm was observed for free 13 CO 3 2Ϫ .…”

“…11a,33 Furthermore, 13 C NMR spectra of [Zn(tren)(H 2 O)] 2ϩ in the presence of H 13 CO 3 Ϫ in D 2 O was studied as a function of pH, and the data are listed in Table 1. At low pH, free 13 CO 2 at 127.5 ppm and H 13 CO 3 Ϫ at 163.1 ppm were observed, whereas at high pH, a peak at 170.8 ppm was observed for free 13 CO 3 2Ϫ . In the pH range 8 to 11, two peaks were recorded: one is strong and another multiple peak is very weak.…”