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

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

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Abstract

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 S0 2 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
Pages (from-to)349-356
Number of pages8
JournalPolyhedron
Volume5
Issue number1-2
DOIs
Publication statusPublished - 1986

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reactivity
Ligands
ligands
Alkynes
Cycloaddition
Cycloaddition Reaction
cycloaddition
alkynes
Polysulfides
Hydrodesulfurization
Bond length
Disulfides
polysulfides
alternations
disulfides
insertion
dissociation
orbitals
synthesis

ASJC Scopus subject areas

  • Biochemistry
  • Inorganic Chemistry
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this

Unique reactivity characteristics of Mo-coordinated S2- 2 and S2- 4 ligands. / Coucouvanis, D.; Hadjikyriacou, A.; Draganjac, M.; Kanatzidis, Mercouri G; Ileperuma, O.

In: Polyhedron, Vol. 5, No. 1-2, 1986, p. 349-356.

Research output: Contribution to journalArticle

Coucouvanis, D, Hadjikyriacou, A, Draganjac, M, Kanatzidis, MG & Ileperuma, O 1986, 'Unique reactivity characteristics of Mo-coordinated S2- 2 and S2- 4 ligands', Polyhedron, vol. 5, no. 1-2, pp. 349-356. https://doi.org/10.1016/S0277-5387(00)84932-3
Coucouvanis, D. ; Hadjikyriacou, A. ; Draganjac, M. ; Kanatzidis, Mercouri G ; Ileperuma, O. / Unique reactivity characteristics of Mo-coordinated S2- 2 and S2- 4 ligands. In: Polyhedron. 1986 ; Vol. 5, No. 1-2. pp. 349-356.
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abstract = "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 S0 2 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.",
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T1 - Unique reactivity characteristics of Mo-coordinated S2- 2 and S2- 4 ligands

AU - Coucouvanis, D.

AU - Hadjikyriacou, A.

AU - Draganjac, M.

AU - Kanatzidis, Mercouri G

AU - Ileperuma, O.

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N2 - 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 S0 2 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.

AB - 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 S0 2 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.

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