Subject: Cyclohexadienes

From: Bert Thomas <[email-masked]>
Date: Tue, 7 May 1996 15:40:00 -0700

Hi,

I haven't followed the whole discourse on MM and AM1 calcs on
1,3-cyclohexadiene, so I will be brief.  Microwave and electron
diffraction studies on 1,3-cyclohexadiene are available.
The structure has C2 symmetry and is well represented at the
RHF/6-31G(d) level.  While in the Houk group, I and others looked
at the electrocyclic reactions of substituted 1,3-cyclohexadienes
and at all levels of theory employed (including AM1) these structures
were staggered about the sp3-sp3 single bond.  The microwave and
electron diffraction references are:

Oberhammer, H. ... JACS 1969, 91, 10
Dallinga, G. ... J. Mol. Struc. 1968, 1, 11
Traetteberg, M.  Acta. Chem. Scand. 1968, 22, 2305
Butcher, S. S.  J. Chem. Phys. 1965, 42, 1830

I hope this helps.

Bert

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