Thermochemistry of Sulfur Atom Transfer. Enthalpies of Reaction of Phosphines with Sulfur, Selenium, and Tellurium, and of Desulfurization of Triphenylarsenic Sulfide, Triphenylantimony Sulfide, and Benzyl Trisulfide

Abstract

The enthalpies of reaction of neat PBu 3 with solid sulfur (-27.1 ( 0.5 kcal/mol), selenium (-20.0 ( 0.6 kcal/ mol), and tellurium (-4.9 ( 0.6 kcal/mol) have been measured by solution calorimetry. The enthalpies of reaction of a series of phosphines with sulfur in toluene solution have been measured as follows (values in kcal/mol): PCy 3 ) -30.9 ( 1.9, PBu 3 ) -28.9 ( 0.3, PMe 3 ) -27.1 ( 0.4, PMe 2 Ph ) -26.0 ( 0.5, PMePh 2 ) -23.8 ( 0.3, PPh 3 ) -21.5 ( 0.3. These values correlate with literature data for enthalpies of protonation and indicate that P to S σ donation is probably the dominant factor in determining the R 3 PdS bond strength, estimates for which range from 88 to 98 kcal/mol. The enthalpies of S atom transfer to PPh 3 by SdAsPPh 3 and SdSbPh 3 in toluene solution are -17.7 ( 1.2 and -21.5 ( 1.0 kcal/mol, respectively. The enthalpy of removal of the central S atom from BzSSSBz by PCy 3 , yielding BzSSBz and SdPCy 3 , is -29.0 ( 1.8 kcal/mol. These data are used to establish a range of enthalpies of S atom transfer in these compounds which spans 31 kcal/mol from SdSbPPh 3 to SdPCy 3 .

On the Chalcogenophilicity of Mercury: Evidence for a Strong Hg−Se Bond in [TmBut]HgSePh and Its Relevance to the Toxicity of Mercury

“…Consideration of the literature indicates that for many systems involving bonds to sulfur and selenium, e.g. E–H,6d E–C6d, E–P,47 and E–transition metal48,49,50 (E = S, Se), the bond to sulfur is generally the stronger; however, there are situations in which the reverse is observed. For example, the opposite trend has been observed for coordination of thio- and selenoethers to transition metals 51.…”

Reactions of Ph3Sb═S with Copper(I) Complexes Supported by N-Donor Ligands: Formation of Stable Adducts and S-Transfer Reactivity

“…Several studies have shown that triphenyl antimony sulfide (Ph 3 Sb=S) is useful for sulfur transfer reactions,9 including for the preparation of transition metal sulfide complexes 10,11. The utility of Ph 3 SbS likely stems from the thermodynamic instability of the Sb-S bond, which is weaker than the related bonds in R 3 E=S (E = P or As) congeners 12. Herein, we report the results of an investigation of the reactivity of Ph 3 Sb=S with selected Cu(I) complexes of N,N,N’,N’ -tetramethyl-2 R ,3 R -cyclohexanediamine (TMCHD) and 1,4,7-trialkyltriazacyclononanes (R 3 tacn; R = Me, Et, iPr).…”

Computational Study of Sulfur Atom-Transfer Reactions from Thiiranes to ER3(E = As, P; R = CH3, Ph)

“…52 ) The reported G3//B3LYP value is 85.1 kcal/mol, 51 which is not significantly different than the value reported here, but both vary from the experimental estimate of 94 kcal/mol. 15 It Ph3AsdS + Me3As f Ph3As + Me3AsdS 1.2 1.0 -1.1 2 a All energy calculations at the MP2 geometry using 6-31+G(d) for S, 6-31G(d) for As and P, and 6-31G for C and H with ZPE included. All values are calculated for 0 K. All energies calculated with G3Large for As, P, and S and 6-31(d) for C and H. b Derived from ref 15.…”

“…15 It Ph3AsdS + Me3As f Ph3As + Me3AsdS 1.2 1.0 -1.1 2 a All energy calculations at the MP2 geometry using 6-31+G(d) for S, 6-31G(d) for As and P, and 6-31G for C and H with ZPE included. All values are calculated for 0 K. All energies calculated with G3Large for As, P, and S and 6-31(d) for C and H. b Derived from ref 15. c Based on the square root of the sum of the square of reported errors.…”