Understanding Reactive Sulfur Species through P/S Synergy

Abstract

We investigated the differential oxidative and nucleophilic chemistry of reactive sulfur and oxygen anions (SSNO − , SNO − , NO 2 − , S 4 2−, and HS − ) using the simple reducing electrophile PPh 2 Cl. In the case of SSNO − reacting with PPh 2 Cl, a complex mixture of mono and diphosphorus products is formed exclusively in the P(V) oxidation state. We found that the phosphine stoichiometry dictates selectivity for oxidation to P=S/ P=O products or transformation to P 2 species. Interestingly, only chalcogen atoms are incorporated into the phosphorus products and, instead, nitrogen is released in the form of NO gas. Finally, we demonstrate that more reducing anions (S 4 2− and HS − ) also react with PPh 2 Cl with P=S bond formation as a key reaction driving force.

Synergistic Activation of Nitrite and Thiocarbonyl Compounds Affords NO and Sulfane Sulfur via (Per)thionitrite (SNO−/SSNO−)

“…While the generation of NO from the reactions of TAA/thioacetate and nitrite is attributed to the intermediacy of SSNO À species as confirmed by UV/Vis and 15 N NMR (Figures S29, S33, S35, and S36), N 2 O is proposed to form through the decomposition of in situ generated HSNO intermediate formed due to the presence of acidic TAA (Figure 5A). [4,15,18] Consistent with previous reports and the present 31 P NMR data showing the interception of transient nitroxyl (HNO) species by Ph 3 P (Figure S30), [30] HSNO is capable of producing HNO, which rapidly dimerizes to provide N 2 O.…”

“…À /SNO À /SSNO À ). [31] The 15 N NMR study on a sample generated from a reaction of LR and 15 NO 2 À in a 1 : 4 molar ratio in CDCl 3 exhibited two resonances at δ( 15 N) = 847.6 and 779.2 ppm rather than the chemical shifts of S 15 NO À /SS 15 NO À (Figures 6 and S37). Guided by the previously reported δ( 15 N) values ranging between 750 and 850 ppm (vs. liq.…”

“…[28] An equimolar reaction between TAA and [TBA][NO 2 ] in acetonitrile cleanly provided acetate (as observed by UV/ Vis and NMR analyses) along with the formation of elemental sulfur S 8 in 72 % gravimetric yield (Figures 5A and S27-S29). 31 P NMR quantification of S 8 using excess Ph 3 P during the reaction of TAA and nitrite provided near quantitative yield (Figure S30). Analysis of the headspace for NO gas revealed 70 % yield (Figure S31).…”

“…Notably, a recent report shows that electrophilic organophosphorus reagent Ph 2 PCl reacts with various nucleophilic reactive S/N/O species (e.g. NO 2 − /SNO − /SSNO − ) [31] . The 15 N NMR study on a sample generated from a reaction of LR and 15 NO 2 − in a 1 : 4 molar ratio in CDCl 3 exhibited two resonances at δ( 15 N) = 847.6 and 779.2 ppm rather than the chemical shifts of S 15 NO − /SS 15 NO − (Figures 6 and S37).…”

“…Hence, the present results outline the transformation of S (oxidation state -II) in CS 2 into biorelevant sulfane sulfur (oxidation state 0) coupled to nitrite reduction. To quantify the S 0 equivalents generated per CS 2 molecule, the reaction of CS 2 and nitrite was carried out in the presence of Ph 3 P (2 equiv) as the sulfane sulfur trap and subsequently analyzed by 31 P NMR spectroscopy to estimate the transformed S 0 species as Ph 3 P=S. 31 P NMR spectrum shows the generation of Ph 3 P=S (0.7 equiv), Ph 3 P=O (0.3 equiv), and unreacted Ph 3 P (1.0 equiv) as obtained from the relative integrations of the 31 P chemical shifts at 43.2, 29.1, and À 5.6 ppm, respectively (Figures 4B and S18).…”