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Please login to access the full content or check if you have access via Method 1: [Bis(dimethylphosphino)ethane]bis(butadiene)titanium(0) by Reduction of [Bis(dimethylphosphino)ethane]tetrachlorotitanium(IV) by Sodium ­Amalgam in the Presence of Butadiene

DOI: 10.1055/sos-SD-002-00576

Mikami, K.; Matsumoto, Y.; Shiono, T.Science of Synthesis, (20032532.

The reduction of the titanium(IV) chloridebis(dimethylphosphino)ethane complex with sodium amalgam in the presence of butadiene afforded [bis(dimethylphosphino)ethane]bis(buta-1,3-diene)titanium(0) (157), which was isolated as blue crystals from hexanes.[‌298‌] Complex 157 catalyzes the dimerization of alkenes (Scheme 81). This proceeds via a coordinated alkene dimer, followed by β-elimination from the ring and subsequent hydrogen addition. This can either lead to elimination of the newly formed alkene or to formation of a further metallacyclopentane complex by reaction with an additional alkene molecule. Propene is converted into 2,3-dimethylbut-1-ene by a mechanism proposed to involve the formation of a metallacyclopentane complex. The extra coordination site needed for the second alkene is probably generated either by dissociation of one phosphine group of bis(dimethylphosphino)ethane, or by the formation of a η2-buta-1,4-diene unit.

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