Reactions of Dienes with Metal Vapors

Ferrocene and chromocene are formed during condensation of iron or chromium atoms with cyclopentadiene  

Vapors of nickel and cobalt react to give compounds containing allyl, cyclopen-tadiene, and cyclopentadienyl ligands  

The molybdenum and tungsten metals react with C5H5 to afford hydrido complexes  

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A very important method of preparation of diene compounds is the condensation reaction of dienes with metal vapors. The reaction is carried out at low temperature and at low pressure in a specifically designed flask containing the diene either neat or in solution. The metal atoms vaporize from the electrically heated metal wire and react with dienes which are present in the liquid phase(Figure 8.7). Often, such condensations of metal vapors with dienes are carried out in matrices at liquid nitrogen temperature. In this manner, the air-stable compounds [M(C4H6)3] (M = Mo, as... 

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