Mechanisms of the Reaction of Elemental Sulfur and Polysulfides with Cyanide and Phosphines**

Abstract

The reactions of elemental sulfur (S8) and polysulfides with nucleophiles are relevant to organic synthesis, materials science and biochemistry, but the mechanisms by which they operate are still unknown due to the inherent thermodynamic and kinetic instability of polysulfide intermediates. Using Density Functional Theory (DFT) calculations at the ωB97X‐D/aug‐cc‐pV(T+d)Z/SMD(MeCN) // ωB97X‐D/aug‐cc‐pVDZ/SMD(MeCN) level of theory, we studied the mechanisms behind the reaction of elemental sulfur and polysulfides with cyanide and phosphines, which quantitatively generate the monosulfide products thiocyanate and phosphine sulfides, respectively. All plausible pathways including nucleophilic decomposition, unimolecular decomposition, scrambling reactions, and attack on thiosulfoxides, have been considered to provide the first comprehensive mechanistic picture for this class of reactions. Overall, intramolecular cyclization is identified as the most favorable decomposition pathway for long polysulfides. For short polysulfides, a mixture of unimolecular decomposition, nucleophilic attack, and scrambling pathways can be expected.

Generation and Reactivity of Polychalcogenide Chains in Binuclear Cobalt(II) Complexes

“…Reaction of cyanide (CN – ) with elemental (neutral) sulfur to generate thiocyanate (SCN – ) has implications in biology in the context of cyanide detoxification. − Reactions of elemental sulfur and polysulfide, organopolychalcogenides, and transition metal–polysulfido complexes , with CN – have also been reported in the literature. The mechanism for the reaction of elemental sulfur and polysulfide with CN – has been studied very recently which suggested intramolecular cyclization to be the most favorable decomposition pathway for long chain polysulfides, while a mixture of unimolecular decomposition, nucleophilic attack, and scrambling pathways was proposed to be operative in the case of short chain polysulfides . The reaction of 9b and 8 with (Bu 4 N)­(CN) was therefore examined using IR spectroscopy (Figures and S100).…”

“…The mechanism for the reaction of elemental sulfur and polysulfide with CN − has been studied very recently which suggested intramolecular cyclization to be the most favorable decomposition pathway for long chain polysulfides, while a mixture of unimolecular decomposition, nucleophilic attack, and scrambling pathways was proposed to be operative in the case of short chain polysulfides. 174 The reaction of 9b and 8 with (Bu 4 N)(CN) was therefore examined using IR spectroscopy (Figures 8 and S100 2− chain and CN − . Identities of both 14 and 15 were confirmed by single crystal X-ray structure determinations (Figure 9).…”

Elemental Sulfur Promoted Cyclization of Aryl Hydrazones and Aryl Isothiocyanates Yielding 2-Imino-1,3,4-thiadiazoles

“…MS spectra were compared with the spectra gathered in the NIST library. Proton and carbon-13 ( 1 H NMR, 13 C NMR) spectra were recorded on Bruker AV 500 or 600 spectrometers using residual solvent or tetramethylsilane (TMS) as reference. Splitting is reported with the following symbols: s = singlet, d = doublet, t = triplet, q = quartet, dd = doublet of doublets, td = triplet of doublets, ddd = doublet of doublets of doublets and m = multiplet.…”

“…4. 5, 152.5, 146.6, 139.9, 130.6, 130.5, 129.7, 128.9, 128.8, 126.2, 126.1, 124.0, 122.3, 121.0 13 C{ 1 H} NMR (151 MHz, CDCl 3 ) δ 155. 3, 150.0, 146.5, 139.9, 133.5, 130.6, 130.4, 130.2, 128.9, 128.8, 126.2, 125.9, 122.3, 120.7, 21.0.…”

1,1‐Diethoxyethane as an interfacial‐stabilizing solvent for lithium–sulfur batteries

“…This is believed to be owing to the intrinsic characteristics of PS; the terminal site of the PS species is composed of highly nucleophilic sulfur anions that are known to promptly undergo chemical reactions with electrophilic functional groups. 31 These functional groups, such as C═O functional groups, are present in typical conventional electrolytes (i.e., carbonate-based electrolytes), which means that these conventional carbonate-based electrolytes cannot be used for LSBs. This is because the PS can easily be consumed in chemical reactions with these conventional electrophilic electrolytes, thereby leading to drastic capacity fading.…”