Floppy Molecules

 Subject:      Floppy Molecules
 Apologies for coming into this late in the day.  There is a
 fairly large literature on "floppy" or "non-rigid"
 I think that the already-mentioned reference to Bunker's
 book "Molecular Symmetry and Spectroscopy" covers the
 most important work in the field.
 But there is much else.  2 references I have to hand are:
 H. Frei, A. Bauder, H. H. Gunthard, "The Isometric Group of
 Nonrigid Molecules", in Top. Curr. Chem., Vol. 81, Large
 Amplitude Motion in Molecules, I, p3, (1979)
 "Symmetries and Properties of Non-Rigid Molecules", Ed. J.
 Maruani and J. Serre, Studies in Physical and Theoretical
 Chemistry, 23, Elsevier, Amsterdam, (1982).
 There is also a recently published book-volume edited by
 Yves Smeyers "Structure and Dynamics of Non-Rigid Molecular
 Systems",  Kluwer, 1994, in which I have an article with
 some perspectives on how to treat the problem of inter-
 conversions between minima of different geometries/symm-
 One small point on the use of the term "fluxional":  I have
 also seen it used to refer to inorganic molecules where no
 valence tautomerisation occurs, the archetypal example of
 which is PF_5.  The Smith-Berry internal rotation which
 interconverts all the indistinguishable Trig-bipy isomers
 doesn't change any bonding very much.
 Richard Bone
 Richard G. A. Bone, PhD.
 Terrapin Technologies, Inc.
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 Tel. +1 (415) 244 9303
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 E-mail  rgab "-at-" trpntech.com