Subject: Re: pi-stacking interactions

From: <[email-masked]>
Date: Thu, 7 May 1998 12:07:34 +0200 (DFT)

Dear CCLers,

Many theoretical studies on pi-stacking interactions have been achieved.

Ab initio calculations yield satisfactory results if high level theoretical levels are used. See:

P. Hobza, H. L. Selzle, E. W. Schlag, Chem. Rev. 1994, 94, 1767 and
references therein.

C. Chipot, R. Jaffe, B. Maigret, D. A. Pearlman, P. A. Kollman, J. Am. Chem.
Soc. 1996, 118, 11217.

An AM1 study on arene-arene complexes has been published:

V. E. Williams, R. P. Lemieux, G. R. J. Thatcher, J. Org. Chem. 1996, 61,
1927.

According to the authors, the results "showed good agreement with
literature data on related experimental systems". In my opinion, the
agreement is purely qualitative. I think that semiempirical methods are not
adequate for pi-stacking studies due to their poor performance of
medium-range interactions:

V. Buss, J. Messinger, N. Heuser, QCPE Bull. 1991, 11, 5.
G. I. Csonka, J. Comp. Chem. 1993, 14, 895.
G. I. Csonka, J. G. Angyan, J. Mol. Struct. (THEOCHEM) 1997, 393, 31.

Finally, MM3 method has been specifically parametrised in order to consider
pi interactions:

N. L. Allinger, Z.-q. Zhu, K. Chen, J. Am. Chem. Soc. 1992, 114, 6120.

However, I think that there are not specific studies on the performance of the
MM3 method on pi-stacking interactions.

Luis Salvatella
Departement de Chimie Theorique
Universite de Nancy I
France