Structural criteria for the mode of bonding of organoactinides and -lanthanides and related compounds

Structural information accumulated during the last 10 years concerning organoactinides and organolanthanides is summarized. A structural definition of covalent and ionic bonding is developed. Within the scope of this definition, consideration of the general structural features and the metal coordination number for a series of structurallly related compounds indicate that an ionic model best explains the organoactinides and - lanthanides. This same model was noted to not work well for the d-metal Mcp/sub 2/ compounds where Cp = tris(cyclopentadienyl) where covalent bonding often predominates. The ionic model was also shown to explain the observed tris(silylamide) complexes from all over the periodic table. (BLM)