Subject: RE: Keto-enol tautomerism studies

From: "Forlani Roberto" <roberto.forlani^at^nikemresearch.com>
Date: Thu, 10 Jun 2004 17:42:52 +0200

Dear CCLers,

	below you'll find my original question about tautomerism computational approaches and all the obtained replies.
Thank you very much to all of them for their kind replies.

Regards,

Roberto Forlani

> 
> 	I'm looking for some general references about keto-enol 
> tautomerism studies with different semiempirical and/or ab 
> initio methods (... not sure about goodness of my keywords in 
> article retrieval). I'm particularly interested in methods comparison.
> 
> I'll summarize all replies.
> 

- Andrea Klamt

Robert,

unfortunately I do not have real results to tell, but only some 
preliminary experiences: With our COSMO-RS solvation model based on BP86 
DFT/COSMO calculations with TZVP basis set we were by almost 5 kcal/mol 
off (just comparing the total free energies of keto and enol forms in 
bulk liquid phases). Since this is far beyond the error of the solvation 
model, it must mainly be an error resulting from the DFT calculation level.

Nevertheless, you will always have to take the solvation appropriately 
into account. Perhaps a look on COSMOtherm for this purpose.

- Uko Maran

Following ref. provides comaprison of semi-emp. gas phase and SCRF 
calculations:

M. Karelson, U. Maran and A. R. Katritzky, 
Theoretical Study of the Keto-Enol Tautomerism in Aqueous Solutions 
Tetrahedron 1996, 52, 11325-11328.

-