Molybdenum complexes ammonia formation

Perhaps chemists will be able to mimic nature without duplicating the iron-sulfur-molybdenum structure. For example, a zirconium complex with tetramethyl cyclopentadiene can bind dinitrogen in a manner that breaks the NON bond, as shown below. Treatment with hydrogen gas results in formation of small amounts of ammonia. Although the yields are too low to make this a viable commercial process, researchers hope to make the process more efficient through chemical modifications and changes in conditions. 

The current experiment involves the preparation of the sterically hindered amine A -ferf-butyl-3,5-dimethylaniline. Other preparations of this amine involve addition of methyllithium to lV-3,5-dimethylphenylacetone imine and the reaction of l-bromo-2,4-dimethylbenzene with terf-butylamine either via aryne formation or by palladium-catalyzed alkylation. The current method, the reaction of tert-butylamine with the 2,4,6-trimethylpyrylium cation, involves inexpensive starting materials and proceeds in high yield. The molybdenum(III) complex of the deprotonated form of this amine, Mo[N(f-Bu)(3,5-C6H3Me2)]3, splits the N=N triple bond in N2 to afford molybdenum(VI) nitrido products. This latter reaction is the key step in the recently discovered catalytic process to convert N2 to ammonia under ambient conditions. 

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