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>From lou_at_degas.scripps.edu Tue Jun 20 15:11 PDT 2000
Date: Tue, 20 Jun 2000 15:11:40 -0700 (PDT)
From: Lou Noodleman <lou_at_scripps.edu>
To: duke_at_citrin.chemie.uni-dortmund.de
Subject: Re: ADF-LIST: Protonation energies
Cc: lou_at_scripps.edu

Dear Frank Glahe,
Another term you may have missed is the Zero-Point-Energy (ZPE) term.
The ZPE term for breaking an N-H or O-H bond (by deprotonating) is
about -7 or -8 kcal/mol. It can be obtained by calculating the vibrational
frequencies for both species, and then evaluating the ZPE term. The remaining
vibrational energy difference can be obtained similarly (as discussed in
the book: Ab initio molecular orbital theory by Hehre, Radom,
 von Schleyer, Pople). Our group has done a fair number of gas phase
deprotonation as well as solvation calculations both for organic and
metal complexes, evaluating also pKa's. You can look at: Richardson et al.,
Int.J.Quantum Chem. 61,207, 1997, Chen et al., J.Phys.Chem. 98,11059, 1994,
Konecny et al., Inorg. chem. 38,940, 1999, Li et al., Inorg. Chem. 38,929,1999.
We are continuing to work on these difficult, but important problems as
 are other groups. There is a recent review in Chem.Rev. by Cramer and Truhlar,
and work by groups like Truong and Stefanovich and C. Lim. A considerable
literature is now developing on these topics.
Lou Noodleman
Scripps
.

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Received on 2000-06-21 19:55:21