Ab initio calculations have been carried out that demonstrate an essentially linear correlation between the vibrational frequency of carbon monoxide and its carbon-13 and oxygen-17 chemical shifts, under a variety of external electrical influences. However, the correlations for carbon-13 and oxygen-17 shifts turn out be in opposite directions. Electronic structure calculations reveal that it is polarization of the electron charge density along the intermolecular axis that changes the chemical shielding oppositely for the carbon and oxygen nuclei. Recent experiments have pointed to just such a correlation in a wide range of carbonmonoxyheme proteins, and so electrical perturbation is a possible cause of distal ligand effects. Furthermore, the experimentally determined correlation of the vibrational frequency with oxygen-17 quadrupole coupling constants is also seen in the calculations.
ASJC Scopus subject areas
- General Chemistry
- Colloid and Surface Chemistry