Nickel(II), copper(II), and zinc(II) complexes of penta-azamacrocyclic ligands. Crystal and molecular structure of 3,6,9,12-tetramethyl-3,6,9,12,18-penta-azabicyclo[12.3.1]octadeca-1(18),14,16-trienezinc(II) perchlorate

Synthesis and solid-state spectroscopic investigation of some novel diorganotin(IV) complexes of tetraazamacrocyclic ligands

“…The cyclic amine-amide and cyclic peptides have many properties analogous to linear peptides and their metal complexes show functionalities resembling those of metalloproteins, thereby, making them of biological interest [15]. A large number of workers [16][17][18] are currently engaged in the synthesis of polyamide macrocycles and their coordination chemistry which is of particular interest in view of two potential donor atoms, i.e., amide nitrogen and amide oxygen [17,[19][20][21][22][23][24][25][26]. However, in the most of the polyamide macrocyclic complexes, amide nitrogen is involved in coordination and not oxygen.…”

Synthesis, Optical Resolution, and X-ray Crystal Structure of a Helical Hexaazamacrocyclic Zinc Complex

“…The zinc complex of this macrocycle has stability (log K**1 = 21.1) greater than those of the analogous [18]aneN« and [15]-aneNs complexes, suggesting that the macrocycle coordinates through all six nitrogen atoms. Due to the four asymmetric nitrogen atoms, there are five possible isomers for pyo2 [ 18]dieneN6…”

“…19 Presumably, this decrease in rate is due to the lower flexibility of the macrocycle or to steric effects. Synthetic schemes for these macrocyclic complexes either have used Zn2+ asa templating metal ion10 Rothermel et al 24 have reported the synthesis of the 18membered hexaazamacrocycle containing two pyridine groups and four aliphatic amines pyo2 [18]dieneNe, shown in Figure 1.…”

“…In order to coordinate through its six nitrogen atoms, pyo2[l 8] dieneNe must twist, pucker, orfold. Whereas [18]aneN6 is potentially capable of an octahedral wrap in two modes, corresponding to meridional or facial disposition of nitrogen donors,25 pyo2[l 8]dieneNi can wrap only in the meridional mode due to the planarity and rigidity imposed by the pyridine groups.…”

“…An inspection of space-filling models indicates that only isomer V allows pyo2 [18]dieneN6 to twist, forming a pseudooctahedral wrap. Furthermore, each of the enantiomeric forms of isomer V can twist in only one direction, as shown in Figure 2.…”