Synthesis and Reactivity of Transition of Metal Homo- and Heterobinuclear Ketene Complexes

Citation

Ho, Suzzy Chen Hsi (1986) Synthesis and Reactivity of Transition of Metal Homo- and Heterobinuclear Ketene Complexes. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/bmj9-a007. https://resolver.caltech.edu/CaltechTHESIS:04152019-104421637

Abstract

The rearrangement of β-phenyltitanacyclobutane (1) to α-phenyltitanacyclobutane (2) is shown through labeling experiments to proceed by a stepwise mechanism. Ring opening of 1 to the metalmethylidene species followed by readdition of styrene affords both complexes 1 and 2.

The reaction of titanacyclobutanes with oxidizing agents produces cyclopropanes in good yield. The stereochemistry of this reaction has been investigated using cis-2,3-dimethyltitanacyclobutane and trans-2-deutero-3-phenyltitanacyclobutane. By the use of ²H NMR, the stereochemistry of each step of the reaction has been determined.

The crystal and molecular structure of zirconaenolate anion Cp₂Zr(η²-OCCH₂-O,C)CH₃Na•2 THE prepared by deprotonation of the corresponding acyl complex has been determined. The reactivity of this anion with electrophilic reagents is studied. Reaction with alkyl halides leads to C-substituted acyl complexes. Reaction with metal chlorides L₂M(CH₃)Cl leads to binuclear ketene complexes (Cp₂ZrCH₃)(µ-η²-OCCH₂-O,C)-(MCH₃L₂) (M = Zr, Pt; L = Cp, phosphines). The mechanism for the formation of these complexes and their reactivities are discussed in detail.

The interaction of phosphonium and sulfoxonium ylides with acyl complexes of titanium and zirconium is examined. Reaction of Cp₂Zr(COR)R' (R,R' = akyl, aryl) with CH₂Pφ₃ and CH₂SO(CH₃)₂ gives enolate complex Cp₂Zr(OCR=CH₂)R'. Treatment of titanocene chloro acyls with CH₂SO(CH₃)₂ affords ketene complexes which react with excess ylides to give titanaoxacyclobutanes. The structure of titanaoxacyclobutane is determined by Dynamic NMR techniques. The zirconium chloro acyls react with CH₂SO(CH₃)₂ to give mixtures of ketene and enolate complexes. Both react further with the ylides to yield zirconaoxacyclobutanes.

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