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In the presence of CO, facile N-N bond cleavage of N(2)O occurs at the formal Mo(II) center within coordinatively unsaturated mononuclear species derived from Cp*Mo[N((i)Pr)C(Me)N((i)Pr)](CO)(2) (Cp* = η(5)-C(5)Me(5)) (1) and {Cp*Mo[N((i)Pr)C(Me)N((i)Pr)]}(2)(μ-η(1):η(1)-N(2)) (9) under photolytic and dark conditions, respectively, to produce the nitrosyl, isocyanate complex Cp*Mo[N((i)Pr)C(Me)N((i)Pr)](κ-N-NO)(κ-N-NCO) (7). Competitive N-O bond cleavage of N(2)O proceeds under the same conditions to yield the Mo(IV) terminal metal oxo complex Cp*Mo[N((i)Pr)C(Me)N((i)Pr)](O) (3), which can be recycled to produce more 7 through oxygen-atom-transfer oxidation of CO to produce CO(2).

Under an atmosphere of CO, the Mo(IV) imido complex Cp*Mo[N(iPr)C(Me)N(iPr)](NSiMe3) (Cp* = η5-C5Me5) (1) serves as a catalyst for production of an isocyanate via metal-mediated nitrene group transfer in benzene solution under mild conditions (55 °C, 10 psi) according to RN3 + CO → N2 + RNCO. Mechanistic and structural studies support a catalytic cycle for nitrene group transfer involving formal Mo(II) monocarbonyl and Mo(IV) (κ2-C,N)-isocyanate intermediates. These results complement an earlier finding that catalytic production of isocyanates can alternatively proceed through oxygen-atom transfer and an isomeric Mo(IV) (κ2-C,O)-isocyanate according to N2O + CNR → N2 + RNCO.

(I(t)Pe)AuBr(2)(N-imidate) complexes, prepared in high yield by oxidative bromination, are active catalysts for 1,5-enyne cycloisomerization. An efficient tandem nucleophilic substitution-1,5-enyne cycloisomerization is promoted by these novel Au(III) precatalysts. Catalyst efficacy is affected by the imidate ligand and the silver salt used (e.g. Ag[Al(OC(CF(3))(3))(4)]).