Background and mechanism

Treatment of the yellow-brown octacarbonyldicobalt, Co2(CO)g, with an acetylene in ethereal or hydrocarbon solvent at room temperature under an inert atmosphere generates over several hours time the red-violet hexacarbonyldicobalt-alkyne complex, Co2(CO)s al-kyne. These species may be isolated and purified under inert atmosphere conditions at room temperature and readily characterized by the usual spectroscopic techniques [89]. Reaction of this complex with an olefin occurs at temperatures ranging from about 60 to 120 °C over a period of hours to days Eq. (36) depicts one of the best examples [1, 90]. 

The mechanistic picture developed for the Pauson-Khand reaction is the result of analyses by many groups of, mostly, product selectivities in widely varied systems. Direct evidence is unavailable, because, aside from the Co2(CO)6-alkyne complexes themselves, few observa- 

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This handbook highlights the limitations of iron, nickel, zinc and their alloys in various water grades and provides vital information on corrosion protection measures. The chapters are arranged by the media leading to individual corrosion reactions, and a vast number of alloys are presented in terms of their behaviour in these media. The key information consists of quantitative data on corrosion rates coupled with commentaries on the background and mechanisms of corrosion behind these data, together with the dependencies on secondary parameters, such as flow-rate, pH, temperature, etc. Where necessary this information is complemented by more detailed annotations and by an immense number of references Usted at the end of each chapter. 

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