Substituted Cyclooctatetraene Complexes of Yttrium and Erbium with Bis(phosphinimino)methanides — Synthesis and Structure

A one pot reaction of Li₂{1, 4‐(Me₃Si)₂C₈H₆}, LnCl₃, and K{CH(PPh₂NSiMe₃)₂} leads to the 1, 4‐bis(trimethylsilyl)cyclooctatetraene bis(phosphinimino)methanide complexes of yttrium and erbium, [{CH(PPh₂NSiMe₃)₂}Ln(η⁸‐{1, 4‐(Me₃Si)₂C₈H₆})] (Ln = Y, Er). Both complexes have been characterized by single crystal X‐ray diffraction. The solid state structures show that the two bulky ligands cause a steric crowding around the lanthanide atom. As a result of this steric crowding both ligands are asymmetrically attached to the lanthanide atom.