Ring size effects among metal complexes with macrocyclic ligands: synthesis, stereochemistry, spectrochemistry, and electrochemistry of cobalt(III) complexes with unsubstituted, saturated tetraaza macrocycles

Mesoporous Silica Functionalized by Cyclam–Metal Groups: Spectroscopic Studies and Numerical Modeling

“…In the cyclam-Ni complex, the four imine groups are not equivalent and this seems to be connected with the nickel electronic configuration. Indeed, former experimental reports on the cyclamNi complexes state on the less constrained geometries, when planar configurations hold and stabilize low-spin for Nickel ions [50,51]. However, high-spin state is compatible with a geometry configuration as trans-octahedral complex [52,53].…”

Reassignment, Isolation, Spectral and X‐ray Characterization of Diastereoisomers of the Macrocyclic Ligand 3,10‐meso‐3,5,7,7,10,12,14,14‐Octamethyl‐1,4,8,11‐tetraazacyclotetradecane and their NiII and CuII Complexes

“…Nickel() complexes of these ligands were obtained from a template reaction of tris[(±)-1,2-propanediamine]nickel() perchlorate, tris[(+)-1,2-propanediamine]nickel() perchlorate, or tris[(-)-1,2-propanediamine]nickel() perchlorate with acetone and were characterized by proton NMR spectroscopy. [6] In addition, the Nickel() complex of 3,10-meso-Me 8 [14]diene was confirmed by X-ray crystallography. [6a,7] In a different approach, the reaction of (±)-1,2-propanediamine hydroperchlorate with acetone yields stereospecifically only the crystalline 3,10-meso-Me 8 [14]diene·2HClO 4 .…”

“…[5] The macrocyclic molecule 3,5,7,7,10,12,14,4,8,diene, which has two chiral centers at the 3 and 10 positions, exhibits three noninterconvertible diastereoisomers, 3S,10R-meso-Me 8 [14]diene (L), 3R,10R-racemic-Me 8 [14]diene, and 3S,10S-racemic-Me 8 [14]diene (Scheme 1). Nickel() complexes of these ligands were obtained from a template reaction of tris[(±)-1,2-propanediamine]nickel() perchlorate, tris[(+)-1,2-propanediamine]nickel() perchlorate, or tris[(-)-1,2-propanediamine]nickel() perchlorate with acetone and were characterized by proton NMR spectroscopy.…”

“…[6] In addition, the Nickel() complex of 3,10-meso-Me 8 [14]diene was confirmed by X-ray crystallography. [6a,7] In a different approach, the reaction of (±)-1,2-propanediamine hydroperchlorate with acetone yields stereospecifically only the crystalline 3,10-meso-Me 8 [14]diene·2HClO 4 . [6a,8] Failure to isolate any C-rac isomer apparently results from a higher solubility of the C-rac salt.…”

“…[6a] The configuration of 3,10-meso is designated as 3S*,10R*-meso. Reduction of 3,10-meso-Me 8 [14]diene with NaBH 4 generates another two chiral centers at the 5 and 12 positions and gives an isomeric mixture of the corresponding saturated macrocycles, 3,10-meso-Me 8 [14]anes. [8] These molecules and their N-alkylated derivatives have been characterized and studied in the field of kinetics, coordination chemistry, and environmental monitoring.…”