Bimetallic systems catalysed reactions

For a further discussion of the structure and properties of bimetallic systems, see Sections 2.6 and 3.2.3 for the preparation of bimetallic catalysts, see Section 4.6 and for the mechanisms by which they work in oxidations, see Section 8.2.2. Most textbooks of physical chemistry have sections on adsorption and catalysis, but they frequently focus on studies made under ultra-high vacuum conditions with single crystal surfaces. While this work produces beautiful pictures, it has limited relevance to the more mundane world of practical catalysis. Other introductory treatments of about the level of this chapter, or slightly more advanced, are available,5,7,11 as are deeper discussions of the kinetics of catalysed reactions.12 14 Industrial processes using catalysts have also been described in detail.15,16... 

Some reactions catalysed by bimetallic systems (adapted from [1]). 

C in the presence of CO, H2O, base and a phase transfer catalyst (particularly 18-crown-6, 87 turnovers). Aromatic nitro compounds are reduced under mild conditions in a genuine bimetallic phase transfer catalysed reaction (reaction 7) , or by a (PtClj (PPhs )2 ]/SnCli,/Et3N system under more forcing conditions. ... 

An account of a method for the homologation of methyl esters, catalysed by a ruthenium-cobalt bimetallic system, may have some future synthetic potential. Six- and seven-membered heterocyclic enamino-esters (74) undergo ring-contraction to give five- and six-membered azacyclic esters (75) in 89-92% yield (Scheme 40). The reactions of dianions derived from carboxylic acids and esters have been reviewed. ... 

Abstract Bimetallic catalysts are capable of activating alkynes to undergo a diverse array of reactions. The unique electronic structure of alkynes enables them to coordinate to two metals in a variety of different arrangements. A number of well-characterised bimetallic complexes have been discovered that utilise the versatile coordination modes of alkynes to enhance the rate of a bimetallic catalysed process. Yet, for many other bimetallic catalyst systems, which have achieved incredible improvements to a reactions rate and selectivity, the mechanism of alkyne activation remains unknown. This chapter summarises the many different approaches that bimetallic catalysts may be utilised to achieve cooperative activation of the alkyne triple bond. 

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