Boese, Roland; Miebach, Thomas; de Meijere, Armin:
[3]Rotane: crystal structure, X-X difference electron density, and phase transition.
1991
In: Journal of the American Chemical Society (J.Am.Chem.Soc.), Jg. 113 (1991), Heft 5, S. 1743 - 1748
Artikel/Aufsatz in Zeitschrift1991Chemie
Titel:
[3]Rotane: crystal structure, X-X difference electron density, and phase transition.
Autor(in):
Boese, RolandLSF; Miebach, Thomas; de Meijere, Armin
Erscheinungsjahr
1991
Erschienen in:
Titel:
Journal of the American Chemical Society (J.Am.Chem.Soc.)
in:
Jg. 113 (1991), Heft 5, S. 1743 - 1748
ISSN:

Abstract:

A newly redetd. x-ray crystal structure of [3]rotane (I) provides structural parameters in close agreement with theor. calcns. Compared to cyclopropane, a shortening of the vicinal bonds at the spiro carbon atoms and a lengthening of the distal bonds is obsd. The latter is apparently due to the increased angular strain at the spiro carbon. In a series of spiro[2.n]alkanes the angle in the (n+1)-membered ring correlates inversely with the length of the distal s bond in the cyclopropane group. The detd. X-X difference electron d. for I strongly corroborates the theor. predicted surface delocalization of electrons in 3-membered rings; this adds an essential argument in favor of the concept of s aromaticity. Upon cooling, the crystal of I undergoes a reversible phase transition at 108.2 K. Most probably the increasing no. of van der Waals contacts in the low-temp. form provides the driving force for the phase transition.