Tuck-in complex

In organometallic chemistry, a tuck-in complex usually refers to derivatives of Cp* ligands wherein a methyl group is deprotonated and the resulting methylene attaches to the metal.

The term "tucked in" was coined to describe derivatives of organotungsten complexes.

[1] Although most "tucked-in" complexes are derived from Cp* ligands, other pi-bonded rings undergo similar reactions.

The original example proceeded via sequential loss of two equivalents of H2 from decamethyltungstocene dihydride, Cp*2WH2.

The Lewis acid attaches to the CH2 group, exposing a vacant site on the electrophilic Zr(IV) centre.