| Title
| - A Family of Oxo-Chalcogenide Molybdenum and Tungsten Complexes,(n-Bu4N)2[M2O2(μ-Q)2(1,3-dithiole-2-thione-4,5-dithiolate)2] (M = Mo, W; Q= S, Se): New Synthetic Entries, Structure, and Gas-Phase Behavior
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| Abstract
| - The reduction of the disulfide bridges in the trinuclear cluster [M3Q7(dmit)3]2- (M = Mo, W; Q = S, Se) results in the [M3Q4(dmit)3]2- complex with a vacant site at the metal-coordination environment. Despite the robustness of the Mo3S4 unit, which remains intact at very high cone voltages as seen in the ESI-MS experiments, these trinuclear complexes degrade in air to give a series of M2O2(μ-Q)2(dmit)2 (M = Mo, Q = S, Se) dimers, where the oxygen atoms are in a syn configuration.
- A new series of complexes with the general formula (n-Bu4N)2[M2O2(μ-Q)2(dmit)2] (where M = Mo, W; Q = S, Se;dmit = 1,3-dithiole-2-thione-4,5-dithiolate) have been prepared. Fragmentation of the trinuclear cluster (n-Bu4N)2[Mo3(μ3-S)(μ-S2)3(dmit)3] in the presence of triphenylphosphine (PPh3) gives the dinuclear compound (n-Bu4N)2[Mo2O2(μ-S)2(dmit)2] {(n-Bu4N)2[2]}, which is formed via oxidation in air from the intermediate (n-Bu4N)2[Mo3(μ3-S)(μ-S)3(dmit)3] {(n-Bu4N)2[1]} complex. Ligand substitution of the molybdenum sulfur bridged [Mo2O2(μ-S)2(dimethylformamide)6]2+ dimer with the sodium salt of the dmit dithiolate also affords the dianionic compound(n-Bu4N)2[2]. The whole series, (n-Bu4N)2[Mo2O2(μ-Se)2(dmit)2] {(n-Bu4N)2[3]}, (n-Bu4N)2[W2O2(μ-S)2(dmit)2] {(n-Bu4N)2[4]}, (n-Bu4N)2[W2O2(μ-Se)2(dmit)2] {(n-Bu4N)2[5]}, and (n-Bu4N)2[Mo2O2(μ-S)2(dmid)2] {(n-Bu4N)2[6]; dmid= 1,3-dithiole-2-one-4,5-dithiolate}, has been synthesized by the excision of the polymeric (Mo3Q7Br4)x phaseswith PPh3 or 1,2-bis(diphenylphosphanyl)ethane in acetonitrile followed by the dithiolene incorporation and furtherdegradation in air. Direct evidence of the presence of the intermediates with the formula [M3Q4(dmit)3]2- (M = Mo,W; Q = S, Se) has been obtained by electrospray ionization mass spectrometry. The crystal structures of (n-Bu4N)2[1], (PPh4)2[Mo2O2(μ-S)2(dmit)2] {(PPh4)2[2]; PPh4 = tetraphenylphosphonium}, (n-Bu4N)2[2], (n-Bu4N)2[4],(PPh4)2[W2O2(μ-Se)2(dmit)2] {(PPh4)2[5]}, and (n-Bu4N)2[6] have been determined. A detailed study of the gas-phase behavior for compounds (n-Bu4N)2[2−6] shows an identical fragmentation pathway for the whole family thatconsists of a partial breaking of the two dithiolene ligands followed by the dissociation of the dinuclear cluster.
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