Intrinsic Lewis base strength based upon valency

COMP 238

Joseph J Rosmus, rosmusj@duq.edu, Joshua A Plumley, plumleyj@duq.edu, and Jeffrey D. Evanseck, evanseck@duq.edu. Department of Chemistry and Biochemistry, Duquesne University, 600 Forbes Ave, Pittsburgh PA, PA 15282
Gilbert Lewis originally defined a base as a molecule that donates a lone pair of electrons. When an acid coordinates to a base, an adduct is formed. Due to its importance, chemists have searched for a way to gauge the strength of a Lewis base. Base strength cannot be determined by direct measurement. Consequentially, it is usually indirectly inferred from the adduct bond strength. However, the adduct bond strength involves other forces which may stabilize or destabilize the bond. Thus, the bond strength does not always correlate with Lewis base strength. Density functional theory and natural bond orbital analysis have been employed to determine the base strength in the gas phase. Based upon Lewis' original ideas concerning valency, we define an “intrinsic Lewis basicity” index based upon excess electron population in the valence orbitals of the coordinating atom, which defines its tendency to donate an electron pair.
 

Poster Session
6:00 PM-8:00 PM, Tuesday, August 18, 2009 Walter E. Washington Convention Center -- Ballroom A, Poster

Division of Computers in Chemistry

The 238th ACS National Meeting, Washington, DC, August 16-20, 2009