Nucleophilicity of the boron atom in compounds R-B, (R = F, Cl, Br, I, CN, NC, CH 3 , SiH 3 , CF 3 , H): a new look at the inductive effects of the group R.

Nucleophilicities N R-B of molecules R-B (R = F, Cl, Br, I, CN, NC, CH 3 , SiH 3 , CF 3 , H) are determined from the equilibrium dissociation energies D e of 70 hydrogen-bonded complexes R-B⋯HX (X = F, Cl, Br, I, HCN. HCCH, HCP). The change in N R-B relative to N H-B of H-B allows a quantitative measure of the inductive effect I R 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 R , suggested by the strong correlation of the N R-B values with the minimum value σ min of the molecular electrostatic surface potential on the 0.001 e Bohr -3 iso-surface along the R-B axis leads to excellent agreement between the two definitions.