Subject: Re:Solvated TS Searches

From: Olga G Dmytrenko <odmitr[at]UDel.Edu>
Date: Fri, 5 Dec 2003 14:53:33 -0500 (EST)

Dear Dr. Hultin,

I think we've had similar problems when did our studies on epoxidation
reactions.

A Computational Study Of The Hydroxyl-Group Directivity In The
Peroxyformic Acid Epoxidation Of The Chiral Allylic Alcohol
(Z)-3-Methyl-3-Penten-2-ol: Control Of Threo Diastereoselectivity Through
Allylic Strain And Hydrogen Bonding, Adam, W.; Bach, R.D.; Dmitrenko, O.;
Saha-Moeller C.R. J.OrgChem 65(20) (2000) 6715-6728

And scipcm model was the best at that time. Then we found that COSMO does
great job and switched to it completely. From my experience, I can tell
that one can do very different TSes optimizations at DFT+COSMO without
much problems. But usually it's better to start from the gas phase TS,
maybe correct the geometry  in accord to the solvent-induced
change of the reaction endo- or exothermicity (solvent can make TS
either earlier or later, or do not affect at all). So, some chemical
intuition is of great help. Usually if optimization in solvent is
terminated abnormally, the increase of TSNUM helps.

We do COSMO in gaussian98. As I see from the Andreas Klamt msg (THANKS!),
it should be great in g03 and in GAMESS programs as well.

Best regards,
Olga