Allyl reaction with chromocene

Although organochromium catalysts are not well characterized, organochromium compounds are thought to bind to the support by reaction with surface hydroxyls as other types do. When Cr(allyl)3 or Cr(allyl)2 is used, propylene is released (59,60). Chromocene loses one ring (52-55), and / -stabilized alkyls of chromium lose the alkane (81). 

However, it is assumed that the active centers are coordinatively unsaturated Cr or Cr centers that are generated by reaction with ethylene (Eq. 8-11). It is also possible to convert the chromate deposited on the silica surface to an active form by high-temperature reduction with CO. In an alternative method of catalyst production, low-valent organochromium compoimds such as chromocene and tris( -allyl)-chromium are used as catalyst precursors. 

With ff-cyclopentadienylcobalt dicarbonyl, it has been shown that when allyl iodide is used a neutral complex w-CsH5Co(ir-C3H5)I is formed in 10% yield, as well as the analogous iodide salt of complex (IV) 48). The reaction of chromocene with allyl iodide does not give an allyl complex (26). 

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