Lead complexes cobalt carbene

The conversion of methanol to ethanol with carbon monoxide and hydrogen has attracted considerable attention. Further carbonylation to higher alcohols occurs much more slowly, but acetic acid formation is a competing reaction and this leads to ester formation. Using CoI2 in presence of PBu 3 as catalyst, the selectivity to ethanol was improved by addition of the borate ion B4072. 399 This was attributed to an enhanced carbene-like nature of an intermediate cobalt-acyl complex by formation of a borate ester (equation 76). This would favour hydrogenolysis to... 

The running order in this chapter is essentially similar to that used in the preceding one. The main section, dealing with metal-carbon Group VIII triads in the order, iron, cobalt, and nickel, and is followed by a shorter section on carbene and carbyne complexes. Oxidative addition or reductive elimination reactions are included only when they lead directly to the formation or rupture of metal-carbon bonds. 

Finally, reference is made to the remarkably facile cyclization which alkynyl Fischer carbene complexes can undergo under conditions normally leading only to alkyne-cobalt complex formation (eq 66) (M = Cr or W R=Ph or Et). 

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