Vibrational circular dichroism in transition-metal complexes. 2. Ion association, ring conformation, and ring currents of ethylenediamine ligands

Signatures of counter-ion association and hydrogen bonding in vibrational circular dichroism spectra

“…Firstly, Nafie et al have reported VCD measurements for the [Co(en) 3 ] 3+ molecule in a solution with 10-fold excess chloride ions. 12,13 As a result, the conclusions of our theoretical investigation can be validated by direct comparison to experiment. Secondly, because the associated Cl À ions are single atoms, no coupling between ''solvent'' and solute modes will take place upon association of the Cl À ions to the [Co(en) 3 ] 3+ molecule.…”

Ethylene diamine post‐synthesis modification on open metal site Cr‐MOF to access efficient bifunctional catalyst for the Hantzsch condensation reaction

“…The ν(NH) and ν(CH) stretching regions demonstrated the presence of ED in framework. It's worth noting that the observed aliphatic C‐H stretching vibrations (2800–2950 cm −1 ) are shifted to larger values and appears a new peak at 3150 cm −1 (shows frequencies of the N‐H group of the ED ligand), as observed when the ED is coordinated to an open metal site of Cr‐MOF . Also, according to the hydroxyl group (appear 3578 cm −1 ) the OH group show in the ED/MIL‐101(Cr).…”

Porous Chromium Terephthalate MIL‐101 with Coordinatively Unsaturated Sites: Surface Functionalization, Encapsulation, Sorption and Catalysis

“…Figure 9c shows the spectra of the bare MIL-101 compound compared with the two samples after ED grafting; the n(NH) and n(CH) stretching regions evidence the presence of ED, the spectrum of which is also reported in the liquid phase, for comparison. It is worth noting that the observed aliphatic C-H stretching vibrations (2800-3000 cm À1 ) are upward shifted, as observed when the molecule is coordinated to a Lewis acid center, [124] therefore clearly demonstrating the selective ED grafting onto CUS Cr(III) in mesoporous cages. Furthermore, as shown on Figure 9d, the concentration of CUS Cr(III) detected by CO adsorption at low temperature undoubtedly decreases with increasing amount of coordinated ED.…”