Iron Polyynes

Partial catalytic hydrogenation of polyynes to give polyenes with cw configuration has been accomplished with a variety of substrates. Palladium catalysts, particularly the Lindlar catalyst ", are generally the most satisfactory. Side-reactions include over-hydrogenation, isomerization of cis to Irons isomers and double-bond migration. 

Cobalt complexes among other metals such as iron and nickel are known to catalyze the growth of carbon nanotube (CNT) by chemical vapor deposition (CVD) [79-81]. Thanks to the thermal stability of the hyperbranched polyyne backbone, spin-coated films of the organometalhc polymer were successfully probed to function as catalyst and arrays of CNT bundles could be prepared (Figure 2.4). This preliminary result already suggests potential application in the field of paUemable tailor-made catalysts. 

The interest in transition metals with <7-bound alkynyl ligands continues, since metal acetyiides are potential nonlinear optical, conducting, or liquid crystalline materials. Their chemistry and applications have been reviewed in 2003 and 2004. Another review dealing on organoiron polymers includes also rigid-rod iron acetyiides. " The chemistry of metal complexes with 1,3-diynes and polyynes was surveyed in 2001. " ... 

A diiron polyyne complex, Cp Fe(CO)2-(CC)n-Fe(CO)2Cp (n=3 or 4) showed site-selective cleavage reaction of the C-C triple bond when it reacted with Fe2(CO)9 or Fe3(CO)i2 (Eq. 25) [36], The second C-C triple bond from the terminal was selectively cleaved at room temperature, although the yield was relatively low. The cleaved fragment was stabilized by three iron metals. Similar... 

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