Phosphorescent complexes of {Mo6I8}4+ with triazolates: [2+3] cycloaddition of alkynes to [Mo6I8(N3)6]2-

(Bu4N)(2)[Mo6I8(N-3)(6)], prepared in a clean high-yield reaction from (Bu4N)(2)[Mo6I8(CH3COO)(6)] and Me3SiN3, undergoes [3+2] cycloaddition with CH3O(O)CC(O)OCH3 with the formation of a novel hexakis(triazolate) complex, (Bu4N)(2)[Mo6I8(N3C2(COOCH3)(2))(6)] with symmetrically coordinated 4,5-di(carbmethoxy)triazol-2-yl ligands. The product was characterized by X-ray analysis, NMR, IR and ESI-mass spectrometry. It undergoes a quasi reversible oxidation in CH3CN at E-1/2 = 1.36 V (vs. Ag/AgCl) and is red-light emissive upon UV photoexcitation. Reaction with methylpropiolate also yields a corresponding hexakis(triazolate) complex, [Mo6I8(N3C2H(COOCH3))(6)](2-), which exists as a 1 : 1 mixture of two isomers. Alkynes that lacking strongly electron-withdrawing substituents fail to undergo the cycloaddition reaction.