Defense Date

11-20-2013

Graduation Date

2013

Availability

Immediate Access

Submission Type

thesis

Degree Name

MS

Department

Chemistry and Biochemistry

Committee Chair

Jeffrey D Evanseck

Committee Member

Ellen S Gawalt

Committee Member

Jeffry D Madura

Committee Member

Douglas J Fox

Keywords

basicity, Lewis, NBO, Valence

Abstract

The Lewis definition of basicity has no single reference to establish a universal order of base strength. To explore valency as an gauge of Lewis basicity, quantum mechanical calculations have been performed using the meta-hybrid density functional M06-2X with Dunning style basis sets. The electronic and thermodynamic properties of 132 isolated Lewis bases and 28 boroamine adducts have been computed. Natural bond orbital (NBO) analysis was conducted to calculate the valence population and to define the excess valency, EV, as a scale of Lewis basicity. A final equation of EV=-1.07(χ ̅_sub-χ_donor )+0.74(r ̅_sub-r_donor) results in a correlation of 0.87 for all investigated bases. The use of this model alleviates the confusion of multiple base scales and underscores the periodic nature of the electronic component of basicity. Combining excess valency with the double-scale equation of Drago resulted in the use of excess valency as a means of predicting adduct bond enthalpies by -∆H=(1.25EV+.10)*E_A+C_B C_A.

Format

PDF

Language

English

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