Molecular Structure of Dicyclopentadienylberyllium (C5H5)2Be

摘要

The molecular structure of gaseous (C5H5)2Be has been determined from electronhyphen;scattering data. The molecule consists of two planar, symmetrical C5H5rings. C1sngbnd;C2= 1.424plusmn;0.002 Aring; and C1sngbnd;H1= 1.070plusmn;0.005 Aring;. The rings are parallel and staggered with a vertical ringmdash;ring distanceh= 3.37plusmn;0.03 Aring;. The CH skeleton thus has point group symmetryD5d. The beryllium atom may occupy two alternative positions on the fivefold rotation axish= 1.485plusmn;0.005 Aring; from one ring andh2= 1.980plusmn;0.010 Aring; from the other. The complete molecule thus has point group symmetryC5v.It appears then that the potential energy curve of the beryllium atom has two minima. This is readily understood from an ionic binding model. The discrepancy between the values found forhandh1+h2is believed to be due to intramolecular motion.