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Carbon dioxide activation by cobalt macrocyles: Evidence of hydrogen bonding between bound CO[sub 2] and the macrocycle in solution

Journal Article · · Inorganic Chemistry; (United States)
DOI:https://doi.org/10.1021/ic00064a015· OSTI ID:5785895
; ; ;  [1]
  1. Brookhaven National Laboratory, Upton, NY (United States)
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The equilibrium between five-coordinate CoL(CO[sub 2])[sup +](L = 5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradeca-4,11-diene) and six-coordinate CoL(CO[sub 2])(CD[sub 3]CN)[sup +] (formed at the expense of the five-coordinate form as the temperature is lowered) was examined by both [sup 1]H 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 [minus]75[degrees]C in CD[sub 3]CN and in a CD[sub 3]CN/THF mixture indicate the existence of four CO[sub 2] adducts, two with intramolecular hydrogen bonds between the bound CO[sub 2] and the amine hydrogens of the ligand: a five-coordinate, non-hydrogen-bonded form (v[sub c[double bond]O] = 1710 cm[sup [minus]1], v[sub NH] = 3208 cm[sup [minus]1]), a five-coordinate intramolecularly hydrogen-bonded form (v[sub C[double bond]O] = 1626 cm[sup [minus]1]), a six-coordinate non-hydrogen-bonded form (v[sub C[double bond]O] = 1609 cm[sup [minus]1], v[sub NH] = 3145 cm[sup [minus]1]). The binding of CO[sub 2] via both its electrophilic center (carbon atom) and its nucleophilic center (oxygen atom) is thus implicated in the stabilization of the CO[sub 2] complex at low temperature.
DOE Contract Number:
AC02-76CH00016
OSTI ID:
5785895
Journal Information:
Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 32:12; ISSN 0020-1669; ISSN INOCAJ
Country of Publication:
United States
Language:
English

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Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ABSORPTION SPECTROSCOPY
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL ACTIVATION
COBALT COMPLEXES
COMPLEXES
ENERGY LEVELS
EXCITED STATES
MAGNETIC RESONANCE
MOLECULAR STRUCTURE
NUCLEAR MAGNETIC RESONANCE
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
RESONANCE
SPECTROSCOPY
STABILIZATION
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TRANSITION ELEMENT COMPLEXES
VIBRATIONAL STATES