MOLECULAR-STRUCTURES OF ALKALINE-EARTH-METAL METALLOCENES - ELECTRON-DIFFRACTION AND ABINITIO INVESTIGATIONS

The thermal average molecular structures of Sr(C5Me5)2 and Ba(C5Me6)2 have been determined by gas electron diffraction. For both compounds the experimental data are consistent with molecular models where the C5Me5 rings are approximately η5-bonded to the metals and with ring centroid ̶ metal ̶ ring centroid angles close to 150°. The metal ̶ carbon bond distances are ra(Sr–C) = 275.0 (8) pm and ra(Ba–C) = 289.8 (10) pm (mean values). The experimental results are compared to calculations on the model compounds Mg(C5H5)2 and Ca(C5H5)2 in a discussion of the bonding and structure of alkaline-earth-metal metallocenes. © 1990, American Chemical Society. All rights reserved.