ic049214y_si_009.cif (81.9 kB)
Effect of Crystal Packing on the Structures of Polymeric Metallocenes○
dataset
posted on 2005-02-21, 00:00 authored by R. E. Dinnebier, Sander van Smaalen, F. Olbrich, S. CarlsonThe pressure dependencies of the crystal structures of the polymeric metallocenes lithium cyclopentadienide (LiCp)
and potassium cyclopentadienide (KCp) have been determined by synchrotron X-ray powder diffraction. The decrease
of the volume of LiCp by 34% up to a pressure of p = 12.2 GPa and of KCp by 23% at p = 5.3 GPa as well as
the bulk moduli of K = 7.7 GPa for LiCp and 4.9 GPa for KCp indicate a high compressibility for these compounds.
The crystal structures of KCp have been determined up to p = 3.9 GPa. An increase of the bend angle is found
from 45° at p = 0 GPa up to 51° at p = 3.9 GPa. This variation is completely explained by a model invoking
attractive K+ Cp- interaction and repulsive nonbonded carbon−carbon interactions. It is proposed that the bend
angle in the polymeric alkali metal metallocenes is the result of the optimization of the crystal packing.