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

Journal Article · Wed Jun 09 00:00:00 EDT 1993 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00064a015· OSTI ID:5785895

Fujita, E; Creutz, C; Sutin, N; Brunschwig, B S ^[1]

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1. Brookhaven National Laboratory, Upton, NY (United States)

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), Vol. 32:12; ISSN 0020-1669
• Country of Publication: United States
• Language: English

Related Subjects

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