Aspects of the lanthanide-carbon sigma-bond

Although the first sigma-bonded organolanthanides were not fully characterized for some 20 years after the isolation of the first pi-cyclopentadienyls, a wide range of these compounds is unfolding. The review discusses synthetic routes to the compounds, both with and without ''supporting'' polyhapto ligands and including the very recent carbenes, exploring the principles behind their isolation. Structural information is critically reviewed, with the effects of bulky ligands and the lanthanide contraction considered. (C) 1997 Elsevier Science S.A.