Novel Mo(V)-Dithiolene Compounds: Characterization of Nonsymmetric Dithiolene Complexes by Electrospray Ionization Mass Spectrometry

Three new Mo(V) dithiolene compounds have been synthesized by addition of alkynes ((Me3Si)2C2 (TMSA), (Me3Si)2C4, and (Ph)2C4 to MoO2S22- in a MeOH/NH3 mixture: [Mo2(O)2(μ-S)2(η2-S2)(η2-S2C2H2)]2- 1, [Mo2(O)(X)(μ-S)2(η2-S2)(η2-S2C2Ph(C2Ph))]2- 2 (X = O or S), and [Mo2(O)2(μ-S)2(η2-S2)(η2-S2C2H(C2H))]2- 3. The structure of
1 as determined by single-crystal X-ray diffraction study (space group Pbca, a = 13.3148(1) Å, b = 15.7467(4)
Å, c = 28.4108(7) Å, V = 5956.7(2) Å3) is discussed. 2 and 3 have been identified by ESMS (electrospray mass
spectrometry), 1H NMR, 13C NMR, and infrared spectroscopies. This investigation completes our previous study
devoted to the addition of DPA (C2Ph2) to MoO2S22- which led to [Mo2(O)(X)(μ-S)2(η2-S2)(η2-S2C2Ph2)]2- 4 (X =
O or S). A reaction scheme is proposed to explain the formation of the different species present in solution. The
reactivity of the remaining nucleophilic site of these complexes (η2-S2) toward dicarbomethoxyacetylene (DMA) is
also discussed.