Disulfide Competition for Phosphine Gold(I) Thiolates: Phosphine Oxide Formation vs. Thiolate Disulfide Exchange

Inorganics

Gamage S. P. Garusinghe²  S. Max Bessey²  Mostapha Aghamoosa²  Meaghan McKinnon²  Alice E. Bruce¹  Mitchell R. M. Bruce¹ 

[1] Department of Chemistry, University of Maine, Orono, ME 04469-5706, USA;

关键词: phosphine gold(I) thiolate;    thiolate disulfide exchange;    phosphine oxide;    ROSEY 2D NMR;   

DOI  :  10.3390/inorganics3010040

来源: mdpi

【 摘 要 】

Phosphine gold(I) thiolate complexes react with aromatic disulfides via two pathways: either thiolate–disulfide exchange or a pathway that leads to formation of phosphine oxide. We have been investigating the mechanism of gold(I) thiolate–disulfide exchange. Since the formation of phosphine oxide is a competing reaction, it is important for our kinetic analysis to understand the conditions under which phosphine oxide forms. ¹H and ³¹P{¹H} NMR, and GC-MS techniques were employed to study the mechanism of formation of phosphine oxide in reactions of R₃PAu(SRʹ) (R = Ph, Et; SRʹ = SC₆H₄CH₃, SC₆H₄Cl, SC₆H₄NO₂, or tetraacetylthioglucose (TATG)) and R*SSR* (SR* = SC₆H₄CH₃, SC₆H₄Cl, SC₆H₄NO₂, or SC₆H₃(COOH)(NO₂)). The phosphine oxide pathway is most significant for disulfides with strongly electron withdrawing groups and in high dielectric solvents, such as DMSO. Data suggest that phosphine does not dissociate from gold(I) prior to reaction with disulfide. 2D (¹H-¹H) NMR ROESY experiments are consistent with an intermediate in which the disulfide and phosphine gold(I) thiolate are in close proximity. Water is necessary but not sufficient for formation of phosphine oxide since no phosphine oxide forms in acetonitrile, a solvent, which frequently contains water.

【 授权许可】

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