Derivatization of Dinitrogen by Molybdenum in Triamidoamine Complexes

The reduction of [N3N]MoCl by an excess of Mg powder in THF under dinitrogen (1 atm) yields the diazenido
species {[N3N]Mo−NN}2Mg(THF)2 (1), which reacts with MCl2(PPh3)2 (M = Ni or Pd) or ZnCl2 to yield
[N3N]Mo(N2) (2). Heating toluene solutions of 2 under dinitrogen yields the homobimetallic dinitrogen complex
[N3N]Mo−NN−Mo[N3N] (3). Derivatization of dinitrogen is achieved by reaction of 1 with (TMS)Cl to yield
the diazenido complex [N3N]Mo−NN−TMS (4). 4 reacts with an excess of MeOTf to give two products, the
dimethyl hydrazido complex {[N(CH2CH2NSiMe3)2(CH2CH2NCH3)]MoN−NMe2}OTf (5) and the diazenido
complex {[(Me3SiNCH2CH2)2NCH2CH2NMe2]Mo−NNSiMe3}OTf (6). Both 5 and 6 react readily with MeMgCl
to yield products arising from methylation at molybdenum, [N(CH2CH2NSiMe3)2(CH2CH2NMe2)]Mo(CH3)(N2TMS) (7) and [N(CH2CH2NSiMe3)2(CH2CH2NMe)]Mo(CH3)(NNMe2) (8), respectively. In 7, the dimethylamino
group is not bound to the metal. Compound 8 is thermally unstable, decomposing via N−N bond cleavage to
yield the nitrido complex [(Me3SiNCH2CH2)2N(CH2CH2NMe)]Mo⋮N (9). X-ray studies are reported for
compounds 1, 2, 5, 6, and 7.