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

D. Coucouvanis; A. Hadjikyriacou; M. Draganjac; M. G. Kanatzidis; O. Ileperuma

doi:10.1016/S0277-5387(00)84932-3

Unique reactivity characteristics of Mo-coordinated S^2-₂ and S^2-₄ ligands

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

^*Corresponding author for this work

Chemistry

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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 S^2-₄ and S^2-₂ ligands. As a result of Mo-S d_π-p_π 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 S^2-₄ 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 S^2-₂ 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 language	English (US)
Pages (from-to)	349-356
Number of pages	8
Journal	Polyhedron
Volume	5
Issue number	1-2
DOIs	https://doi.org/10.1016/S0277-5387(00)84932-3
State	Published - 1986

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry
Materials Chemistry

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10.1016/S0277-5387(00)84932-3

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@article{d271170c217e46ecb42bc5b5ac35ffbc,

title = "Unique reactivity characteristics of Mo-coordinated S2-2 and S2-4 ligands",

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 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.",

author = "D. Coucouvanis and A. Hadjikyriacou and M. Draganjac and Kanatzidis, {M. G.} and O. Ileperuma",

year = "1986",

doi = "10.1016/S0277-5387(00)84932-3",

language = "English (US)",

volume = "5",

pages = "349--356",

journal = "Polyhedron",

issn = "0277-5387",

publisher = "Elsevier Limited",

number = "1-2",

}

TY - JOUR

T1 - Unique reactivity characteristics of Mo-coordinated S2-2 and S2-4 ligands

AU - Coucouvanis, D.

AU - Hadjikyriacou, A.

AU - Draganjac, M.

AU - Kanatzidis, M. G.

AU - Ileperuma, O.

PY - 1986

Y1 - 1986

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 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.

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 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.

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ER -

Unique reactivity characteristics of Mo-coordinated S^2-₂ and S^2-₄ ligands

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