Unique reactivity characteristics of Mo-coordinated S2-2 and S2-4 ligands

D. Coucouvanis*, A. Hadjikyriacou, M. Draganjac, M. G. Kanatzidis, O. Ileperuma

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

103 Scopus citations


The synthesis of the new dithiolene complexes, [{(MeOOC)2C2S2}2Mo(μ2-S)]-2 and [OMo(S2C2(COOMe)2)2]-, is reported. These complexes are obtained by the reaction of dicarbomethoxyacetylene (DMA) with either [(S4)Mo(S)(μ2-S)2Mo(S)(S4)]2- or [(CS4)Mo(S)(μ2-S)2Mo(S)(CS4)]2- and [OMo(S4)2]2-, respectively. The reaction of [(S4)Mo(O)(μ2-S)2Mo(O)(S2)]2- with DMA results in the new dithiolene complex [{(MeOOC)2C2S2}Mo(O)(μ2-S)]-2, which is the isomeric form of the vinyl disulfide complex obtained in the reaction of the [(S2)Mo(O)(μ2-S)2Mo(O)(S2)]2- complex with DMA. The difference in reactivity between the two complexes that contain the same [Mo2O2S2]2+ core is attributed to the intrinsically different reactivity characteristics of the S2-4 and S2-2 ligands. As a result of Mo-S dπ-pπ bonding an alternation in the SS bond lengths is observed in virtually all of the structurally characterized Mo-S4 units. The consequent weakening of the SS bonds adjacent to the MoS bonds allows for the ready dissociation of S02 from the Mo-coordinated S2-4 ligands. This weakening also accounts for the facile formation of dithiolenes in cycloaddition reactions of alkynes with the Mo-S4 units. By comparison, the SS bond in side-on Mo-coordinated S2-2 ligands is strengthened as a result of depopulation of the ligand π*-orbitals. Reactions of the latter with alkynes do not proceed by cycloaddition. Instead, insertion into the MoO bond has been reported for at least one such reaction. The importance of activated polysulfide ligands in the hydrodesulfurization reaction is discussed.

Original languageEnglish (US)
Pages (from-to)349-356
Number of pages8
Issue number1-2
StatePublished - 1986

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry


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