Reactions nitrido intermediates

In the managanese system [Mn3(i7-C5Me5)3(/i,-NO)3(/i,3-NO)] (279), very similar chemistry is observed but in addition, reduction of the nitrosyl group occurs, yielding the imido cluster [Mn3(i7-C5Me5)3(/u,3-NH)(/i2-NO)3] in low yield. Such a reaction undoubtedly proceeds by a nitrido intermediate, though the exact mechanism is, at present, unknown. 

In 1983, Groves demonstrated the stoichiometric aziridination of alkenes from a manganese-imido complex generated in situ from an isolable (porphyrin)man-ganese-nitrido intermediate (Scheme 1) [4]. This reactivity has recently been exploited with success by DuBois, Carreira and coworkers in the context of (salen)manganese-derived systems for the amination of enol ether derivatives (Scheme 2) [5,6,7,8]. Although not isolated, aziridine intermediates are probably involved in these reactions. 

Nitrido ligands are often formed from 0x0 precursors by reactions with hydrazine derivatives. More details of the formation of hydrazido and diazenido species will be given in Section 5.3.2.10. Here, only those complexes which still contain 0x0 ligands and, thus may be regarded as intermediates of this conversion are regarded. The dithiocarbamato complex... 

The nitrido complex was applied to the direct asymmetric animation with a silyl enol ether as a substrate. Although several examples for achiral aminations of silyl enol ethers have been reported [32], an asymmetric version of reagent-controlled reaction has not appeared except for the one recent example [33] and the diastereoselective reactions with silyl enol ethers having a chiral auxiliary [34], The amination, which is presumed to take place via an aziridine intermediate [5g, lid,32], proceeded smoothly to give the A-tosylated a-aminoketone in 76% yield with 48% ee. When the same silyl enol ether was treated with complex 15 under Carreira s condition, the TV-trifluoroacetylated a-aminoketone was obtained in 58 % yield with 79 % ee (Scheme 24). 

The two isostructural clusters [Co6N(CO)i5] and [Rh6N(CO)i5] were synthesized by reaction of the octahedral clusters [M6(CO)i5] (M = Co, Rh) with nitrosonium tetrafluoborate. Better yields of the rhodium species were obtained by treatment, in a strongly reducing medium, of [RhyjCOjie] " with NO (diluted 1 1 with CO). The reactions are complex and no intermediate step could be identified. However, a nitrosyl derivative is very likely to be involved, and subsequent reduction, by the reaction medium or the starting reduced carbonyl itself, would yield the nitrido cluster. 

Nitrido clusters have also been proposed as models of intermediate species in many important catalytic reactions such as the Haber process and the reduction of NO c pollutants. Several surface reactions involving NO or N2 are known to occur via an adsorbed nitrogen atom in the Haber process the mechanism is believed to occur via formation of the metal nitride followed by successive addition of hydrogen atoms to the nitrogen, giving ammonia.t ... 

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