From: Rzepa, Henry (h.rzepa$##$ic.ac.uk)
Date: Fri Apr 09 1999 - 04:03:37 EDT
Can I ask the collective pool of organic expertise out there
what the largest stereoelectronic effect known to them is?
For example, the anomeric effect reciprocally aligns oxygen lone pairs
with C-O sigma * orbitals in systems such as O-C-O, and the energetics
of this interaction are thought to be about 4-6 kcal/mol.
I am really searching for similar alignments of lone pairs with bonds
that might generate energy differences which depend on the orientation
of the lone pair. We think we have
found a system where concurrent multiple such interactions cause an
energy difference of perhaps 12 kcal/mol (calculated!) and
would like to place it in context of how large such effects might get.
More interestingly, the ground state for our reactants shows one
direction for stabilisation, which completely reverses at the transition
state for the reaction.
Dr Henry Rzepa, Dept. Chemistry, Imperial College, LONDON SW7 2AY;
mailto:rzepa$##$ic.ac.uk; Tel (44) 171 594 5774; Fax: (44) 171 594 5804.
URL: http://www.ch.ic.ac.uk/rzepa/
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