Abstract
The equilibrium between five-coordinate CoL(CO2)+ (L=5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) and six-coordinate CoL(CO2)(CD3CN)+ (formed at the expense of the five-coordinate form as the temperature is lowered) was examined by both 1H NMR and FT-IR. The equilibration is rapid on the NMR time scale, but the spectra of the limiting forms have been derived from the temperature dependence of the spectrum. The FT-IR spectra measured over the range 25 to -75°C in CD3CN and in a CD3CN/THF mixture indicate the existence of four CO2 adducts, two with intramolecular hydrogen bonds between the bound CO2 and the amine hydrogens of the ligand: a five-coordinate, non-hydrogen-bonded form (νC=O = 1710 cm-1, νNH - 3208 cm-1), a five-coordinate intramolecularly hydrogen-bonded form (νC=O = 1626 cm-1), a six-coordinate non-hydrogen-bonded form (νC=O = 1609 cm-1, νNH = 3224 cm-1), and a six-coordinate intramolecular hydrogen-bonded form (νC=O = 1544 cm-1, νNH = 3145 cm-1). The binding of CO2 via both its electrophilic center (carbon atom) and its nucleophilic center (oxygen atom) is thus implicated in the stabilization of the CO2 complex at low temperature.
| Original language | English |
|---|---|
| Pages (from-to) | 2657-2662 |
| Number of pages | 6 |
| Journal | Inorganic Chemistry |
| Volume | 32 |
| Issue number | 12 |
| Publication status | Published - 1993 |
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ASJC Scopus subject areas
- Inorganic Chemistry
Cite this
Carbon dioxide activation by cobalt macrocycles : Evidence of hydrogen bonding between bound CO2 and the macrocycle in solution. / Fujita, Etsuko; Creutz, Carol; Satin, Norman; Brunschwig, Bruce S.
In: Inorganic Chemistry, Vol. 32, No. 12, 1993, p. 2657-2662.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Carbon dioxide activation by cobalt macrocycles
T2 - Evidence of hydrogen bonding between bound CO2 and the macrocycle in solution
AU - Fujita, Etsuko
AU - Creutz, Carol
AU - Satin, Norman
AU - Brunschwig, Bruce S.
PY - 1993
Y1 - 1993
N2 - The equilibrium between five-coordinate CoL(CO2)+ (L=5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) and six-coordinate CoL(CO2)(CD3CN)+ (formed at the expense of the five-coordinate form as the temperature is lowered) was examined by both 1H NMR and FT-IR. The equilibration is rapid on the NMR time scale, but the spectra of the limiting forms have been derived from the temperature dependence of the spectrum. The FT-IR spectra measured over the range 25 to -75°C in CD3CN and in a CD3CN/THF mixture indicate the existence of four CO2 adducts, two with intramolecular hydrogen bonds between the bound CO2 and the amine hydrogens of the ligand: a five-coordinate, non-hydrogen-bonded form (νC=O = 1710 cm-1, νNH - 3208 cm-1), a five-coordinate intramolecularly hydrogen-bonded form (νC=O = 1626 cm-1), a six-coordinate non-hydrogen-bonded form (νC=O = 1609 cm-1, νNH = 3224 cm-1), and a six-coordinate intramolecular hydrogen-bonded form (νC=O = 1544 cm-1, νNH = 3145 cm-1). The binding of CO2 via both its electrophilic center (carbon atom) and its nucleophilic center (oxygen atom) is thus implicated in the stabilization of the CO2 complex at low temperature.
AB - The equilibrium between five-coordinate CoL(CO2)+ (L=5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) and six-coordinate CoL(CO2)(CD3CN)+ (formed at the expense of the five-coordinate form as the temperature is lowered) was examined by both 1H NMR and FT-IR. The equilibration is rapid on the NMR time scale, but the spectra of the limiting forms have been derived from the temperature dependence of the spectrum. The FT-IR spectra measured over the range 25 to -75°C in CD3CN and in a CD3CN/THF mixture indicate the existence of four CO2 adducts, two with intramolecular hydrogen bonds between the bound CO2 and the amine hydrogens of the ligand: a five-coordinate, non-hydrogen-bonded form (νC=O = 1710 cm-1, νNH - 3208 cm-1), a five-coordinate intramolecularly hydrogen-bonded form (νC=O = 1626 cm-1), a six-coordinate non-hydrogen-bonded form (νC=O = 1609 cm-1, νNH = 3224 cm-1), and a six-coordinate intramolecular hydrogen-bonded form (νC=O = 1544 cm-1, νNH = 3145 cm-1). The binding of CO2 via both its electrophilic center (carbon atom) and its nucleophilic center (oxygen atom) is thus implicated in the stabilization of the CO2 complex at low temperature.
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M3 - Article
AN - SCOPUS:0000334387
VL - 32
SP - 2657
EP - 2662
JO - Inorganic Chemistry
JF - Inorganic Chemistry
SN - 0020-1669
IS - 12
ER -