Understanding the chemical reactivity of phenylhalocarbene systems:: an analysis based on the spin-polarized density functional theory

Global and local indices based on the spin-polarized density functional theory (SP-DFT) have been used to rationalize the philicity power and spin polarization pattern of a family of singlet substituted phenylhalocarbenes, (pYPhXC, Y = -NO2 , -CN, -CHO, -F, -H, -CH3 , -OH, -OCH3 , -NH2 ; X = -F, -Cl, -Br). The local reactivity may be traced out by the simple condensed-to-atoms model for the SP-DFT Fukui functions, namely f(NS,k)(+) and f(SS,k)(+). For the addition of some singlet phenylhalocarbenes on tetramethylethylene a linear correlation among the global (omega(N)) and local electrophilicity index (omega(N,C)), and the observed rate constants were found. This result supports a mechanistic model where the carbene adds to the olefin in a single step that is controlled by the carbene electrophilicity. These results emphasize the usefulness of general SP-DFT philicities in the rationalization of chemical reactivity at initial stages of reactions that could involve both charge transfer and spin polarization processes.