Molybdenum imido complexes

C. Electronic Structure and Reactivity of Molybdenum Nitrido and Imido Complexes... 

Schrock and coworkers have generated and tested more than forty molybdenum and tungsten imido complexes with pincer iridium complex for AM [59]. In general, tungsten complexes perform better than molybdenum complexes, presumably due to... 

Imido complexes also react with organic electrophiles. For example, the molybdenum-imido complex in Equation 13.87 reacts with methyl bromide to generate the metal dibromide and trialkylaiulinium bromide. Simple alkylations of an 0x0 group to generate an aUcoxide product are uncommon, but one example of alkylation of a zironocene-oxo complex is shown in Equation 13.88. One example of a related silylation to generate a siloxide complex is shown in Equation 13.89. 

The catalysts for these reactions are derived from both molybdenum and ruthenium, although products with higher enantiomeric excess have been obtained to date with molybdenum catalysts. As noted above, this molybdenum catalyst is based on the structure of Schrock s original bisalkoxide catalyst, but with an optically active bisnaphtholate in place of the two tertiary fluoroalkoxides. These catalysts can be used as isolated complexes or they can be generated in situ from the imido carbene molybdenum bistriflate DME complex and the diolate, as shown in Equation 21.16, or from the bispyrrolyl complex, as shown in Equation 21.17. ... 

The development of well-defined ROMP initiators has expanded the scope of the metathesis reaction, permitting the controlled polymerisation of highly functionalised monomers. Schrock s well-defined olefin metathesis initiators became available in the mid 1980s and they were based on alkoxy imido complexes of tungsten and molybdenum of general... 

Stepwise conversion of dinitrogen co-ordinated to molybdenum into an amine and an imido-complex. Relevance to the reactions of nitrogenase... 

The possible formation of molybdenum imido complexes during the reaction was also considered, but no conclusion concerning their possible role could be drawn. Note that a catalytic cycle in which a molybdenum complex reduces nitrobenzene (to aniline) forming an intermediate molybdenum-oxo complex has indeed been reported, but the reducing agent was a thiol, not CO... 

The reaction of [Ru3(GO)n] dianion with molybdenum bis(imido) complexes [Mo(NAr)2Gl2(dme)] led to the isolation of new high-low valent clusters Ru3(GO)i2 Mo(NAr)2 (Ar = G6H3Me2-2,6 163). These compounds are unstable in polar solvents, such as THF, which may reflect the strong polarization of the Ru-Mo bonds and the electron deficiency at the molybdenum center. 

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