Molybdenum complexes nitride

Nitrido molybdenum complexes have been reported for MoVI, Mov, and MoVI. Among these, MoVI nitrides have been the most extensively studied. For the other two classes of nitrido molybdenum complexes, phosphine and thioalkoxide ligands are common, as they are suggested to stabilize the lower oxidation states through n-back bonding. 

Ligand exchange reactions with nitrido molybdenum complex 56 has been documented (Eq. (19)). Treatment of 56 with 2 equiv. of HX (X = Cl or Br) leads to the formation of 57 which, following treatment with triethylamine, afforded 58, wherein a halide has been substituted for the azide ligand found in 56 [27]. The introduction of a nitride onto a Mov complex has been carried out by treatment of Mom or Mo ... 

Monomeric non-oxo molybdenum(V) complexes have been isolated with nitride (N3 ), imide (NR2-) and amide (NRR -) ligands, which may act as models for intermediates in the degradation of dinitrogen in nitrogenase. However, no molybdenum(V) compounds are yet known which correspond to the diazenide or hydrazide analogues of the molybdenum(IV) complexes described in Section 36.4.2.3. 

This method has been used most widely, but it is limited to the availability of reactive nitrido complexes. The molybdenum nitrides simply abstract sulfur from episulfides (MeCHCH2S) or... 

There are selected examples of the use of additional nitrogen sources such as NSC1, N2, and NC13 (Eqs. (29,30)). The molybdenum nitride halide complexes were isolated from the reaction of a MoVI complex and NSC1 in the presence of Cl- or F [34]. Cummins reported the remarkable reaction of low-valent Mom triamide with N2 (1 atm) to afford the corresponding nitride 80 (Eq. (29)). The presence of bulky amide ligands is critical to the success of the reaction, for it prevents the formation of the stable dimer [(ArRN)3Mo]2. 

In retrospect, it is ironic to it that when I met Ernst Schumacher in 1969 (he was then Professor at the University of Bern in Switzerland) we did not talk about the experiments he did at Zurich in the same building where I was at that time. Instead, his interest focussed on our work on borazine transition metal compounds and we discussed in some detail whether it would be possible to incorporate metal atoms like chromium or molybdenum between the layers of hexagonal boron nitride (BN) in a similar way as it can be done with graphite. In the course of these discussions I did not mention that, after I had moved to Zurich, we had begun to investigate the reactivity of nickelocene towards both nucleophilic and electrophilic substrates. The reason was that we were still at the beginning, and while we had been able to prepare a series of monocyclopentadienyl nickel complexes from Ni(C5H5)2 and Lewis bases, our attempts to obtain alkyl- or acyl-substituted nickelocenes by the Friedel-Crafts reaction failed. 

This type of reaction also works with complex catalysts resulting from the decomposition of molecular molybdenum nitrides such as 7 [14, 17]. The thermolysis product (Structure 8) is mostly 5-MoN (eq. (12)), and the incorporated oxygen is likely to originate from air and moisture. In the absence of ammonia, a product with lower nitrogen content (Mo/N = 1 0.68) is obtained [17]. 

The side-on -coordinated N2 attains a nitride-like structure and is comparatively reactive. Thus, the formation of a side-on metal N2-complex in the nitrogenase is a reasonable way for N2-activation (for rev. see Ref.170)), but it should be mentioned that end-on -complexes have also been discussed as models171). Recent experiments showed170) that side-on -metal N2-complexes built up on reduced oxo-molybdenum in the valence state +4 and coordinated by cystein lead to diimid-for-mation followed by a rapid disproportion or decomposition of diimid and subsequent reduction of the generated hydrazine to NH3. The reaction sequence is given by ... 

An impressive synthetic advance is the complete cleavage of the N—N bond of N2 by well-characterized, isolable compounds. The three-coordinate molybdenum(III) tris-anilide complex (3a) reacts quantitatively with 0.5 equivalents of N2 at ambient temperature to give the molyb-denum(VI) nitride (5a).There is no evidence that analogous tris-alkoxomolybdenum(III) and tris-thiolatomolybdenum(III) conmlexes can cleave N2, although the alkoxide can cleave N2 in combination with the anilide.Steric effects play an important role, as the related anilide complex (3b) does not split The mechanism of the reaction involves the formation of a... 

Nitride, ruthenium cluster complex, 26 287 Nitrido, ruthenium clusters, 26 286 Nitrogen, iridium(III) complex, 26 119 Nitrosyls, molybdenum, 26 132 tungsten, 26 133... 

Bindl, M., Stade, R., Heilmann, E. K., Picot, A., Goddard, R., and Fiirstner, A. (2009) Molybdenum nitride complexes with PhsSiO ligands are exceedingly practical and tolerant precatalysts for alkyne metathesis and efficient nitrogen transfer agents. J. Am. Chem. Soc., 131, 9468-9470. 

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