Agostic interactions in organometallic compounds. A Cambridge Structural Database study

Agostic interaction geometries, C–H ⋯ M (M = Li, Group 4 or 5 transition metal or other), have been investigated with data retrieved from the Cambridge Structural Database. Analysis of both neutron- and X-ray-derived structures shows that a strengthening of the H ⋯ M agostic bond is accompanied by a corresponding weakening of the C–H bond. A similarity in behaviour of Li to the heavier transition metals is observed in these agostic interactions. Di- and tri-bridged C–H ⋯ Li geometries involving alkyl groups occur in both intra- and inter-molecular cases.