Reductions of the in situ generated CO and N-2 complexes of Cummins' molybdenum(III) tris(anilide) complex, viz. {[}Mo(L)\{N(Ar')Bu-t\}(3)] (L=CO or N-2, Ar'=3,5-dimethylphenyl), using a dimagnesium(I) compound, {[}\{((Mes)Nacnac)Mg\}(2)] ((Mes)Nacnac={[}HC(MeCNMes)(2)](-), Mes=mesityl), are reported. Reduction of {[}Mo(CO)\{N(Ar')Bu-t\}(3)] afforded a mixture of products, three of which were isolated in low yield and crystallographically characterized. These were a molybdenum(II) tris(carbamoyl) complex, {[}((Mes)Nacnac)Mg\{mu-(O=){[}Bu-t(Ar')N]C\}(3)Mo(CO)(3)] 1, a magnesium(II) carbamate, {[}\{((Mes)Nacnac)Mg{[}mu-O2CN(Ar')Bu-t]\}(2)] 2, and the 1,3-diamino-1,2,3-trione, Bu-t(Ar')NC3(=O)(3)N(Ar')Bu-t 3. The mechanisms of formation of these products are speculated upon. The reduction of {[}Mo(N-2)\{N(Ar')Bu-t\}(3)] with {[}\{((Mes)Nacnac)Mg\}(2)], in the presence of the N-heterocyclic carbene, :C\{N(Me)C(Me)\}(2) TMC, gave the heterobimetallic molybdenum(II) diazenido complex, {[}((Mes)Nacnac)(TMC)Mg(mu-N-2)Mo\{N(Ar')Bu-t\}(3)] 4, in a low-moderate isolated yield. Reaction of this with chlorotrimethylsilane afforded an essentially quantitative yield of the known silyldiazenido complex, {[}(Me3SiN2)Mo\{N(Ar')Bu-t\}(3)] 5.