ABSTRACT
This chapter aims to investigate the electronic spectra of cyanocobalamin and the potential energy curve along the Co-C elongated bond. To obtain a more accurate explanation of the S1 potential energy surfaces, more dependable energy of the intermediate related to the internal conversion mechanism and the excited-state geometry of cyanocobalamin were studied by means of time-domain density functional theory calculations. The chapter shows fascinating findings with the hydrogen atoms of the alkyl group being replaced by highly electronegative fluorine. In addition, the fluoroalkylcobaloximes obviously showed that the total or partial fluorination of an alkyl group causes a shortening of both the axial Co-N and Co-C bond lengths as compared to the alkylcobaloximes. This result was explained on the basis of the difference in the steric and electronic properties of the alkyl and the corresponding fluoroalkyl group.
