1191248-07-3Relevant academic research and scientific papers
Heterolytic cleavage of disulfides by frustrated lewis pairs
Dureen, Meghan A.,Welche, Gregory C.,Gilbert, Thomas M.,Stephan, Douglas W.
, p. 9910 - 9917 (2010/01/06)
The addition of diphenyl disulfide (PhSSPh) to tBu2P(C 6F4)B(C6F5)2 (1) affords the zwitterionic phosphonium borate [tBu2P(SPh)(C6F 4)B(SPh)(C6F5)2] (2), while the addition of a base or donor solvent to 2 effected the liberation of disulfide and the formation of [tBu2P(C6F4)B(donor) (C6F5)2]. The reaction of 1 with S8 gave tBu2P(S)(C6F4)B(C6F 5)2 (3). In a similar fashion, the frustrated Lewis pair of tBu3P/B(C6F5)3 reacts with RSSR to give [tBu3P(SR)]-[(RS)B(C6F5)3] (R = Ph (4), p-tolyl (5), iPr (6)). In contrast, the corresponding reaction of BnSSBn yields a 1:1:1 mixture of tBu3P=S, Bn2S, and B(C6F5)3. Species 4 reacts with p-tolylSSp-tolyl to give a mixture of 4,5, PhSSPh, and p-tolyISS p-tolyl, while treatment of 5 with PhSSPh afforded a similar mixture. To probe this, a crossover experiment between [tBu3P(SPh)][B(C6F 5)4] (7) and [NBu4][(p-tolylS)B(C 6F5)3] (9) was performed. The former species was prepared by a reaction of 4 with [Ph3C][B(C6F 5)4], while cation exchange of [(Et2O) 2Li(p-tolylS)B(C6F5)3] (8) with [NBu4]Br gave 9. The reaction of compounds 7 and 9 gave a statistical mixture of the cations [tBu3P(SR)]+ and anions [(RS)B(C6F5)3]-, R = Ph, Sp-tolyl. The mechanism of this exchange process was probed and is proposed to be an equilibrium involving disulfide and the frustrated Lewis pair. Crystallography data are reported for compounds 4-8, and the natures of the P-S cations are examined via DFT calculations.
