Conformations of Dimethoxydimethylsilane:  Matrix Isolation Infrared and ab Initio Studies

Abstract

Conformations of dimethoxydimethylsilane (DMDMS) were studied using matrix isolation infrared spectroscopy, by trapping the silane in argon and nitrogen matrixes. The matrix was deposited using both an effusive and a supersonic jet source. The effusive source was maintained at two different temperatures, viz. 298 and 433 K, during deposition to alter the conformational population of the silane. The experimental results were supported by computations performed at both the HF and B3LYP levels, using 6-31++G** basis set. Vibrational frequency calculations were carried out to assign the experimental features and also to ensure that the computed structures did indeed correspond to minima. A conformer with a G+/-G-/+ structure was found to be the ground state, while G+/-T and G+/-G+/- structures were the next higher energy conformers with energies of 1.32 and 1.48 kcal/mol, respectively. Natural bond orbital analysis was carried out at both HF/6-31++G** and B3LYP/6-31++G** level which indicated that the charge-transfer hyperconjugative interactions largely determine the conformational preferences in this molecule. This interaction appears to be smaller in DMDMS than in the corresponding carbon analogue, dimethoxypropane (DMP).

Conformational Landscape of Tri-n-butyl Phosphate: Matrix Isolation Infrared Spectroscopy and Systematic Computational Analysis

“…It is therefore imperative to screen out conformers that are expected to have large energies, relative to the ground state conformer. On the basis of our earlier work on trimethyl phosphate (TMP), − triethyl phosphate (TEP), , acetals/ketals, − and silanes − (all of which have a structural similarity with TBP), it has now become clear that a combination of hyperconjugative (the effect arises due to the delocalization interactions) and steric interactions decide the conformational preferences in these molecules. The study of trimethyl phosphite (TMPhite) which lacks a PO group, has highlighted the importance of the PO group in conformational preferences …”

Influence of Branching on the Conformational Space: Case Study of Tri-sec-butyl Phosphate Using Matrix Isolation Infrared Spectroscopy and DFT Computations

“…The structure–property correlation assumes significance, as understanding at the molecular level in deriving the properties in bulk becomes indispensable. Earlier in our laboratory, a variety of systems, such as acetals–ketals, − silanes, − and carbonates, , were studied for conformations using matrix isolation infrared spectroscopy. These studies highlighted that the conformations of carbons attached to oxygens are driven through hyperconjugative charge transfer interaction and steric factor decides the conformations of rest of the carbons.…”

Unraveling the Conformational Landscape of Triallyl Phosphate: Matrix Isolation Infrared Spectroscopy and Density Functional Theory Computations

“…It is, therefore, imperative to find out the entire conformational picture of TAP through a simplified approach. On the basis of our earlier work on trimethyl phosphate (TMP), − triethyl phosphate (TEP), , acetals/ketals, − silanes, − carbonates, , and phosphite, we concluded that a combination of hyperconjugative (arises due to the delocalization interactions) and steric interactions decides the conformational preferences in these molecules. It is interesting to probe the conformations of TAP as the knowledge on conformations would serve as a platform to understand its chemistry in the condensed phase.…”