Beiträge zur Chemie der Silicium‐Schwefel‐Verbindungen. XXIV. Schwingungsspektroskopische Untersuchungen der Acidität von Silanthiolen; quantitative Zusammenhänge zwischen der Struktur und den δ⁻n̈(SH)‐, HNP‐ und pK‐Werten

Abstract

Für Vertreter von Silanthiolen wurde die Verschiebung der SH‐Valenzschwingungsbande bestimmt. Der Zusammenhang zwischen δν(SH) des Thiols und seiner Struktur wurde ermittelt. Die Beziehungen zwischen δν(SH)‐, HNP‐ und pK‐Werten wurden festgestellt.

Variable-temperature X-ray diffraction study of structural parameters of NH---S hydrogen bonds in triethylammonium and pyridinium silanethiolates

“…Stretching vibrations of the thiol group S-H are observed within the range 2500 to 2600 cm À1 (Baranowska et al, 2012;Biswal et al, 2010;Kieninger & Ventura, 2011;Dołęga et al, 2012;Yablonskii et al, 1973;Rozenberg et al, 1999;Becker et al, 1982;Wojnowski & Herman, 1976;Mielcarek & Dołę ga, 2016). We observe this band for TDST at 2556 cm À1 (Fig.…”

“…DFT calculations were performed using the ADF program (Version 2014.01; Baerends et al, 2013;Guerra et al, 1998;Scott & Radom, 1996) with the GGA BLYP-D XC potential (Becke, 1988;Lee et al, 1988) and TZP basis set in the SCF model as implemented in ADF and using the GAUSSIAN09 program with B3LYP hybrid functional and 6-31G(d,p) basis set (Becke, 1993;Frisch et al, 2009;Lee et al, 1988;Miehlich et al, 1989;Vosko et al, 1980) with Grimme's correction for dispersion with Becke-Johnson damping (Grimme et al, 2011). The relaxed potential energy surface scans were performed using GAUSSIAN09 [B3LYP/6-31G(d,p)].…”

Protonation of the Cysteine Axial Ligand Investigated in His/Cys c-Type Cytochrome by UV–Vis and Mid- and Far-IR Spectroscopy

“…We thus conclude that the Cys axial ligand of M58C becomes protonated upon heme reduction, since Cys58 is the only Cys residue of the protein not involved in covalent linkage of the heme. The Cys58 ν­(SH) mode frequency is at the lower limit of those reported in the literature for thiols involved as donors in very strong hydrogen bonds. − Since the structural data on M58C (Scheme ) evidence an interaction between Cys58 and Gln50, we propose that the protonated Cys58 interacts with the carbonyl group of Gln50 in M58C RED . Note that, although in Scheme the Gln50 amine group points toward the Cys thiol, the other conformer with the carbonyl group pointing toward the SH could also be fitted in the electron density (not shown).…”

Imidazolium silanethiolates relevant to the active site of cysteine proteases. A cooperative effect in a chain of NH+⋯S− hydrogen bonds

“…A weak n SH band is usually registered between 2550 and 2600 cm À1 . 39,[42][43][44] The n SH of cysteine was reported to peak at 2550-2592 cm À139 whereas a very weak band n SH of tri-tert-butoxysilanethiol was measured at 2592 cm À1 . 43 The solid state FT-IR spectrum of polycrystalline 2 features a very broad and intensive absorption in the region of -SH and hydrogen bonded NH stretching modes; the absorption band is centered at about 2375 cm À1 (Fig.…”