Using zirconium half-sandwich complexes as building blocks in a new class of Zr-M heterobimetallics containing unsupported Zr-M bonds (M = Fe, Ru, Co)

Article abstract of DOI:10.1021/om00011a060

A new class of Zr-M heterobimetallic complexes (M = Fe, Ru, Co) containing the {CH₂(CH₂-NSiMe₃)₂(Cp)Zr} fragment as a building block has been synthesized by salt metathesis of CH₂(CH₂NSiMe₃)₂(Cp)ZrCl (5) with K[CpM′(CO)₂] (M′ = Fe, Ru) and Na[Co(CO)₃(PR₃)] (R = Ph, Tol). The zirconium half-sandwich complex 5 was obtained in four reaction steps from ZrCl₄ via the spirocyclic complex [CH₂(CH₂NSiMe₃)₂]₂Zr (1), the (diamido)dichlorozirconium complex CH₂(CH₂NSiMe₃)₂ZrCl₂ (2), and its soluble THF-adduct CH₂(CH₂NSiMe₃)₂-ZrCl ₂(THF)₂ (3). The latter was converted to 5 in good yield by reaction with LiCp. The Zr-Fe heterodinuclear complex CH₂(CH₂NSiMe₃)₂(Cp)Zr-Fe(CO) ₂Cp (6) has been characterized by X-ray crystal structure analysis which has established the presence of an unsupported Zr-Fe bond. The v(CO) infrared bands of the CpM′(CO)₂ moieties in the Zr-M′ complexes (M′ = Fe, Ru) indicate a significant ionic contribution to the Zr-M′ bonding.