C1-insertion reactions at cyclodimeric (η2-acetaldehyde)zirconocene complexes

Article abstract of DOI:10.1016/0022-328X(95)05730-D

Carbonylation of dimethylzirconocene, followed by treatment with zirconocene dihydride, benzyl chloride and then methyllithium, gave the (η²-acetaldehyde)zirconocene dimer (9) as a mixture of trans- and cis-isomers isolated in a 1.5:1 ratio under kinetic control and in a 1:1.7 ratio under thermodynamic control, respectively.Complexes trans-9/cis-9 were treated with carbon monoxide to give the trans-10/cis-10 monoinsertion products, and with isonitriles RNC (R=CH2SiMe3 (a), CMe3 (b)) to give the mono- and bis-insertion products trans- and cis-11(a,b) and 12(a,b), respectively.Complex 12a was characterized by X-ray diffraction.In all cases the trans/cis stereochemical information was predominantly retained in the products, which indicates that dimettalic pathways are favoured in these insertion reactions of the metallatricyclic (η²-aldehyde) metallocene dimers.Keywords: (η²-Aldehyde)zirconocenes; Carbonylation; Isonitrile insertion; Iminoacyl complexes; CO insertion