MS2(Me2PC2H4PMe 2)2 (M = Mo, W): Acid-base properties, proton transfer, and reversible protonolysis of sulfido ligands

Steven J. Smith; C. Matthew Whaley; Thomas B. Rauchfuss; Scott R. Wilson

doi:10.1021/ic051443c

MS₂(Me₂PC₂H₄PMe ₂)₂ (M = Mo, W): Acid-base properties, proton transfer, and reversible protonolysis of sulfido ligands

Steven J. Smith, C. Matthew Whaley, Thomas B. Rauchfuss, Scott R. Wilson

Chemistry

Research output: Contribution to journal › Article › peer-review

Abstract

The acid-base reactivity of MS₂(dmpe)₂, where M = Mo (1) and W (2) and dmpe = Me₂PCH₂CH₂PMe ₂, was examined. Compounds 1 and 2 arise via the one-pot reaction of (NH₄)₂MS₄ and dmpe. Protonation of these species gives the stable salts [MS(SH)(dmpe)₂]X. The pK_a's of the Mo and W compounds are estimated to be 16.5 and 15.5, respectively. Protonation causes the M=S distances to diverge from 2.24 Å to 2.06 and 2.57 Å, whereas the Mo-P distances do not change appreciably. ¹H and ³¹P NMR studies for [1H]BAr^F₄ reveal that the proton exchange is competitive with the NMR time scale; at low temperatures, individual signals for both the parent disulfide and its conjugate acid can be observed. Treatment of 1 with excess HOTf liberates H₂S to afford [MoS(OTf)(dmpe)₂]OTf, which forms an adduct with CD ₃CN and regenerates 1 upon treatment with SH^-/Et ₃N solutions. Consistent with its ready protonation, complex 1 is methylated, and the use of excess MeOTf gives [MoS(OTf)(dmpe)₂] ⁺ and Me₂S in a rare example of double alkylation at a sulfido ligand.

Original language	English (US)
Pages (from-to)	679-687
Number of pages	9
Journal	Inorganic Chemistry
Volume	45
Issue number	2
DOIs	https://doi.org/10.1021/ic051443c
State	Published - Jan 23 2006

ASJC Scopus subject areas

Physical and Theoretical Chemistry
Inorganic Chemistry

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10.1021/ic051443c

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@article{ee298acfd2694537a1d9267711b2e19e,

title = "MS2(Me2PC2H4PMe 2)2 (M = Mo, W): Acid-base properties, proton transfer, and reversible protonolysis of sulfido ligands",

abstract = "The acid-base reactivity of MS2(dmpe)2, where M = Mo (1) and W (2) and dmpe = Me2PCH2CH2PMe 2, was examined. Compounds 1 and 2 arise via the one-pot reaction of (NH4)2MS4 and dmpe. Protonation of these species gives the stable salts [MS(SH)(dmpe)2]X. The pKa's of the Mo and W compounds are estimated to be 16.5 and 15.5, respectively. Protonation causes the M=S distances to diverge from 2.24 {\AA} to 2.06 and 2.57 {\AA}, whereas the Mo-P distances do not change appreciably. 1H and 31P NMR studies for [1H]BArF4 reveal that the proton exchange is competitive with the NMR time scale; at low temperatures, individual signals for both the parent disulfide and its conjugate acid can be observed. Treatment of 1 with excess HOTf liberates H2S to afford [MoS(OTf)(dmpe)2]OTf, which forms an adduct with CD 3CN and regenerates 1 upon treatment with SH-/Et 3N solutions. Consistent with its ready protonation, complex 1 is methylated, and the use of excess MeOTf gives [MoS(OTf)(dmpe)2] + and Me2S in a rare example of double alkylation at a sulfido ligand.",

author = "Smith, {Steven J.} and Whaley, {C. Matthew} and Rauchfuss, {Thomas B.} and Wilson, {Scott R.}",

year = "2006",

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AU - Rauchfuss, Thomas B.

AU - Wilson, Scott R.

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N2 - The acid-base reactivity of MS2(dmpe)2, where M = Mo (1) and W (2) and dmpe = Me2PCH2CH2PMe 2, was examined. Compounds 1 and 2 arise via the one-pot reaction of (NH4)2MS4 and dmpe. Protonation of these species gives the stable salts [MS(SH)(dmpe)2]X. The pKa's of the Mo and W compounds are estimated to be 16.5 and 15.5, respectively. Protonation causes the M=S distances to diverge from 2.24 Å to 2.06 and 2.57 Å, whereas the Mo-P distances do not change appreciably. 1H and 31P NMR studies for [1H]BArF4 reveal that the proton exchange is competitive with the NMR time scale; at low temperatures, individual signals for both the parent disulfide and its conjugate acid can be observed. Treatment of 1 with excess HOTf liberates H2S to afford [MoS(OTf)(dmpe)2]OTf, which forms an adduct with CD 3CN and regenerates 1 upon treatment with SH-/Et 3N solutions. Consistent with its ready protonation, complex 1 is methylated, and the use of excess MeOTf gives [MoS(OTf)(dmpe)2] + and Me2S in a rare example of double alkylation at a sulfido ligand.

AB - The acid-base reactivity of MS2(dmpe)2, where M = Mo (1) and W (2) and dmpe = Me2PCH2CH2PMe 2, was examined. Compounds 1 and 2 arise via the one-pot reaction of (NH4)2MS4 and dmpe. Protonation of these species gives the stable salts [MS(SH)(dmpe)2]X. The pKa's of the Mo and W compounds are estimated to be 16.5 and 15.5, respectively. Protonation causes the M=S distances to diverge from 2.24 Å to 2.06 and 2.57 Å, whereas the Mo-P distances do not change appreciably. 1H and 31P NMR studies for [1H]BArF4 reveal that the proton exchange is competitive with the NMR time scale; at low temperatures, individual signals for both the parent disulfide and its conjugate acid can be observed. Treatment of 1 with excess HOTf liberates H2S to afford [MoS(OTf)(dmpe)2]OTf, which forms an adduct with CD 3CN and regenerates 1 upon treatment with SH-/Et 3N solutions. Consistent with its ready protonation, complex 1 is methylated, and the use of excess MeOTf gives [MoS(OTf)(dmpe)2] + and Me2S in a rare example of double alkylation at a sulfido ligand.

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