Nucleophilicity of diatomic Lewis bases MA in Hydrogen-bonded Complexes MA⋯HX: Influence of Group and Row of M in the Periodic Table. 1

Abstract

Nucleophilicities N MA of diatomic Lewis bases MA acting as hydrogen-bond acceptors in complexes MA⋯HX are reported. The molecules MA were chosen so that the atom M adjacent to the atoms A directly involved in the hydrogen bonds belonged to Groups 13, 14, 15, 16 and 17 of the Periodic Table. The effects of changing atom M from Rows 1 to 4 within a given Group were also investigated. The hydrogen-bond donors HX involved in the complexes were HF, HCl, HBr, HI, HCCH, and HCP. Nucleophilicities N MA were determined from dissociation energies D e for the process MA⋯HX = MA + HX by using D e = cN MA .E HX + d, where E HX are electrophilicities of the Lewis acids HX, and c and d are constants. The order of NM A values was found to be: Row 4 > Row3~ Row2 >> Row 1 in each of the Groups 13, 15, 15, 16 and 17. The effect of adding an H atom to MA to give linear triatomic molecules HMA is considered. The reduced nucleophilicities И MA = N MA /σ min (σ min is the minimum value of the molecular electrostatic surface potential of MA) as a function of Group and Row of atom M were also discussed for diatomic molecules MA. 1 Dedicated to Professor Resnati, celebrating a career in fluorine and noncovalent chemistry on the occasion of his 70 th birthday.