Theoretical Study of the Gauche and Trans Conformers of SiH2X–CH2X, SiH2F–CH2Y and SiH2Y–CH2F (X = F, Cl, Br, I and Y = Cl, Br, I) in the Gas and Solution Phases

Microwave, r0 Structural Parameters, Conformational Stability, and Vibrational Assignment of (Chloromethyl)fluorosilane

“…Previous studies of (chloromethyl)­chlorosilane determined the enthalpy difference between the two conformers to be 175 and 177 cm –1 with trans being more stable. , Similarly, the trans conformer was also found to be the more stable conformer for studies on (chloromethyl)­bromosilane which determined the enthalpy difference to be 175 and 216 cm –1 . , Collectively, these studies, including this study, have a qualitative agreement in conformational stability. If the enthalpy difference for (chloromethyl)­bromosilane is higher than 175 cm –1 , then it would confirm earlier theoretical predictions that the energy difference increases when the halogen atom on the silyl group becomes larger in size …”

“…If the enthalpy difference for (chloromethyl)bromosilane is higher than 175 cm −1 , then it would confirm earlier theoretical predictions that the energy difference increases when the halogen atom on the silyl group becomes larger in size. 2 The most probable reasons for not observing the high energy gauche conformer in the microwave spectra of the sample are mainly due to the conformational relaxation of (chloromethyl)fluorosilane due to supersonic expansion. The same pattern was observed for 1-hexanal where high energy conformers were also not detected.…”

“…According to calculations for all (halomethyl)­halosilane derivatives, the trans conformer was predicted as the most stable form. The energy differences between the two conformers and the rotational barrier height of (halomethyl)­halosilane compounds increases as the size of halogen increases . Theoretical studies help to understand conformational stability, structural parameters, enthalpy differences, and the rotational barrier heights of (halomethyl)­halosilane.…”