Synthesis, Spectroscopic, and Structural Characterization of Organyl Disulfanides and a Tetrasulfanide

Abstract

Various room-temperature-stable monoorganylpolysulfanides of the form X + RSn -(n ≥ 2) were synthesized in a simple and versatile one-step process starting from sodium thiolates and elemental sulfur. The compounds were characterized by X-ray crystal structure analysis, NMR spectroscopy, microelemental analysis and electrospray mass ionization spectrometry including collision-induced dissociation experiments. While these salts are well-defined species as crystals, they undergo complex equilibria in solution. In one case, compounds ranging from n = 1-8 have been observed in solution. Structural features, dynamics in solution as well as thermochromic properties of one of the compounds, PPh4 + PhS2 -, are investigated in detail by temperature-and pressure-dependent X-ray crystal structure analysis. The experimental data is complemented by periodic boundary density functional theory calculations on the crystal structures, as well as energy decomposition analyses.

Synthesis, Isolation, and Characterization of a Phenylsulfane-Selenolate Compound

“…The energetic maximum (non-zero-point-corrected electronic energies) is in all cases found at a dihedral angle of 90°with values around 30 kJ mol −1 . This high barrier is comparable to the torsional barrier of the π-conjugated benzaldehyde In general, the [PhSSe] − anion is structurally very closely related to the [PhS 2 ] − anion 11,12 (Table S1). The C−S−Se bond angle in the former, amounting to 106.99( 14 During our search for crystal structures in the CCDC similar to the title compound, we were surprised by the paucity of terminal, singly bound selenide species that are not stabilized by an adjacent carbon−carbon double bond.…”

“…This high barrier is comparable to the torsional barrier of the π-conjugated benzaldehyde molecule which is also located around 30 kJ mol - 1 16-18 and the torsional barrier in [PhS2]anion, amounting to 37 kJ mol -1 . 12 Figure 2: C-C-S-Se dihedral angle scan of the [PhSSe]anion in steps of 10°. Maximum is at -90° (30 kJ mol -1 ).…”

“…In general, the [PhSSe]anion is structurally very closely related to the [PhS2]anion 11,12 (Table S1). The C-S-Se bond angle in the former amounting to 106.99 (14) During our search for crystal structures in the CCDC similar to the title compound we were surprised by the paucity of terminal, singly bound selenide species that are not stabilized by an adjacent carbon-carbon double bond.…”

“…This can be explained by a molecular orbital analysis as described for the [PhS 2 ] − anion. 12 To see how much this delocalization is worth in terms of energy, we performed a density functional theory (DFT) C−C−S−Se dihedral scan in steps of 10°on the anion, with all other structural parameters allowed to relax. We used four different functionals (PBE0, B3LYP, M06-L, and TPSS) and the def2-TZVPD basis set (Figure 2 for PBE0, Figure S1 for B3LYP, M06-L, and TPSS).…”

“…According to NMR, the exchange reactions for [PhSSe] − are faster than for [PhS 2 ] − , since for the former, on contrast to the latter, anion peak separation was not achieved even at −40 °C. 12 In addition, 77 Se-NMR in MeCN-d 3 was attempted at temperatures ranging from −30 to 80 °C (Figure S5). In all cases, the measured peaks were extremely broad and hampered a clean interpretation.…”