Nucleophilicity of the boron atom in compounds R-B, (R = F, Cl, Br, I, CN, NC, CH3, SiH3, CF3, H): a new look at the inductive effects of the group R

Abstract

Nucleophilicities N of molecules R-B (R = F, Cl, Br, I, CN, NC, CH, SiH, CF, H) are determined from the equilibrium dissociation energies D of 70 hydrogen-bonded complexes R-B⋯HX (X = F, Cl, Br, I, HCN. HCCH, HCP). The change in N relative to N of H-B allows a quantitative measure of the inductive effect I of each group R because only the group R affects the electron density associated with the axial non-bonding electron pair carried by the boron in R-B. An alternative definition of I, suggested by the strong correlation of the N values with the minimum value σ of the molecular electrostatic surface potential on the 0.001 e Bohr iso-surface along the R-B axis leads to excellent agreement between the two definitions.