A cascade reaction: ring-opening insertion of dioxaphospholane into lutetium alkyl bonds

Geometrically constrained dioxaphospholane rings were incorporated into a bis(phosphinimine)carbazole ligand (HL) in an effort to generate an ancillary ligand system that is capable of supporting reactive lutetium alkyl functionalities and resistant to cyclometalation reactivity. This new ligand was used to prepare a lutetium dialkyl species, LLu(CH2SiMe3)2; however, the complex exhibited low thermal stability at ambient temperature. This dialkyl compound was found to be highly susceptible to a cascading inter- and intramolecular reaction that resulted in the sole formation of an asymmetric bimetallic tetraalkoxide complex. The product of this reaction, generated by the ring-opening insertion of dioxaphospholane moieties into lutetium-carbon bonds, was characterized by multinuclear NMR spectroscopy and single crystal X-ray diffraction.