The Structure and Conformation of (CH₃)₃CSNO

Abstract

The gas-phase molecular structure of (CH3 )3 CSNO was investigated by using electron diffraction, allowing the first experimental geometrical parameters for an S-nitrosothiol species to be elucidated. Depending on the orientation of the -SNO group, two conformers (anti and syn) are identified in the vapor of (CH3 )3 CSNO at room temperature, the syn conformer being less abundant. The conformational landscape is further scrutinized by using vibrational spectroscopy techniques, including gas-phase and matrix-isolation IR spectroscopy, resulting in a contribution of ca. 80:20 for the anti:syn abundance ratio, in good agreement with the computed value at the MP2(full)/cc-pVTZ level of approximation. The UV/Vis and resonance Raman spectra also show the occurrence of the conformational equilibrium in the liquid phase, with a moderate post-resonance Raman signature associated with the 350 nm electronic absorption.

Electronic Properties and Ionic Photodissociation of Thionitrite Compounds RSNO [R=(CH3)3C- and (CH3)2CH-]

“…In our case, the extension of this behavior toward tertiary species is also valid, provided that R is electron donating as the tert ‐butyl group. The change in the order of the virtual orbitals between I and II , mostly explained by the stabilization of the π*(NO) for compound II , can be also analyzed by examining their UV‐Vis spectra . In effect, the HOMO→ LUMO transitions for I and II occur at 550 and 590 nm, respectively in the experimental spectra, in qualitative agreement with our TIY spectra.…”

“…Now the He(I) PE spectrum of (CH 3 ) 3 CSNO is depicted in Figure , and the experimental and theoretical ionization energies are listed in Table . The geometry of both syn and anti conformers of (CH 3 ) 3 CSNO in the ground electronic state belongs to the C S symmetry point group . Thus, the canonical molecular orbitals of type a′ are typically σ‐orbitals lying in the symmetry plane, while those of type a“ are π‐orbitals.…”

Computational Structural Biology of S-nitrosylation of Cancer Targets

“…S -nitrosothiols exhibit a highly complex chemistry, which represents a real challenge for theoretical studies. In the last decade, efforts have been dedicated to the development of an accurate structural and electronic description of the -SNO group, by both experimental and theoretical means ( 174 – 176 ). Concerning theoretical investigations, a certain amount of high-level quantum chemistry studies has been performed on small RSNOs (mainly with R = H,Me).…”

Structure and Stability Studies of Pharmacologically RelevantS-Nitrosothiols: A Theoretical Approach

“…A better understanding of how the stability of RSNO compounds in aqueous media is related to their chemical structure is therefore clearly needed in view of developing novel drug candidates for therapeutic uses. Actually, this issue has already motivated a number of theoretical works that have tried to clarify the chemical properties of the SNO function, providing estimations for the BDEs of several model systems. − Calculations and experiments reported by Bartberger et al , have provided a new consistent picture of the conformational behavior of the RSNOs. Their results suggest a competing steric effect that favors the anti orientation of the RSNO group when the R group is large.…”