W. Luef, R. Keese*, H. Bürgi
May 6, 1987
Citations
0
Influential Citations
12
Citations
Journal
Helvetica Chimica Acta
Abstract
The configuration of the spiro centre in polycyclic compounds containing a spiro[4.4]nonane substructure is analyzed in terms of symmetry coordinates. As revealed by X-ray structures of such compounds, the local distortions around the quaternary C-atom are dominated by a decrease of the ring-bond angles at the spiro centre and a twist of one ring relative to the other. The planoid deformations given by the planarization index PC are comparatively small for spiro[4.4]nonanes, which contain either no additional bridges between the rings or only α,β′–or β,β′-polymethylene bridges. This indicates that the local strain in the spiro C(C)4 fragments is rather small.