The ring-puckering potential energy function and theoretical calculations for silacyclopent-2-ene-d0 and 1,1-d2 and the difluoro and dichloro derivatives

Al‐Saadi, Abdulaziz A.; Meinander, N.; Laane, Jaan

doi:10.1016/j.jms.2007.01.002

Cited by 6 publications

(6 citation statements)

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“…The potential energy constant for eq and the calculated reduced masses for each are given in Table . As found before, the hydride is slightly puckered with a barrier of 49 cm –1 and the fluoride is planar. The chloride is essentially planar with a tiny calculated blip of a barrier of 4 cm –1 , and the dibromide has a calculated barrier of 36 cm –1 .…”

Section: Resultssupporting

confidence: 75%

“…This molecule is very floppy and much less rigid than the asymmetric silacyclopent-2-enes. We have previously speculated that the 2SiCP molecule may have some pπ–dπ bonding between the silicon atom and the double bond, − and this may account for the greater rigidity of the asymmetric 2-enes.…”

Section: Resultsmentioning

confidence: 99%

“… a Units for a are cm –1 /Å 4 ; units for b are cm –1 /Å 2 . The reduced mass is in atomic units. b From CCSD/cc-pVTZ computations. c From MP2/cc-pVTZ computations. d Reference . e Reference . …”

Section: Resultsmentioning

confidence: 99%

“…The far-infrared, Raman, and microwave investigations of the ring-puckering vibration of the four-membered rings and pseudo-four-membered rings have been the subject of a number of reviews. − Among the five-membered rings that were studied are silacyclopent-3-ene (3SiCP) and silacyclopent-2-ene (2SiCP). 3SiCP was found to be planar with a nearly perfect quartic oscillator PEF. − 2SiCP was initially believed to be planar and highly rigid, − but a reanalysis of the spectra showed it to be puckered with a dihedral angle of 13° and a barrier to the planarity of 49 cm –1 . In the same study, it was gratifying to see that the ab initio calculations did an excellent job of predicting the structure and barrier.…”

Section: Introductionmentioning

confidence: 99%

“…3SiCP was found to be planar with a nearly perfect quartic oscillator PEF. 18−20 2SiCP was initially believed to be planar and highly rigid, 21−23 but a reanalysis of the spectra 24 showed it to be puckered with a dihedral angle of 13°and a barrier to the planarity of 49 cm −1 . In the same study, it was gratifying to see that the ab initio calculations did an excellent job of predicting the structure and barrier.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical Calculations, Microwave Spectroscopy, and Ring-Puckering Vibrations of 1,1-Dihalosilacyclopent-2-enes

et al. 2020

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High-level theoretical CCSD/cc-pVTZ computations have been carried out to calculate the structures and ringpuckering potential energy functions (PEFs) for 1,1-difluorosilacyclopent-2-ene (2SiCPF 2 ) and 1,1-dichlorosilacyclopent-2-ene (2SiCPCl 2 ). The structure and PEF for 1,1-dibromosilacyclopent-2-ene (2SiCPBr 2 ) were obtained by ab initio MP2/cc-pVTZ computations. The parent silacyclopent-2-ene (2SiCP) is puckered with a 49 cm −1 barrier to planarity, 2SiCPF 2 has a planar ring system, 2SiCPCl 2 has a calculated tiny 4 cm −1 barrier but is essentially planar, and the dibromide has a calculated barrier of 36 cm −1 . Microwave spectra of seven isotopic species of 2SiCPF 2 were recorded on a chirped pulse, Fourier transform microwave (CP-FTMW) spectrometer in the 6−18 GHz region. The a-type and b-type transitions were observed. The rotational constants and three quartic centrifugal distortion constants were determined for the parent, 29 Si, 30 Si, and all singly substituted 13 C isotopologues in natural abundance. This allowed for the determination of the heavy-atom structure of the ring and showed the ring to be planar. The experimentally determined rotational constants and geometrical parameters agree very well with the theoretical values and confirm the planarity of the five-membered ring. A comparison of the PEFs for the silane and the three dihalides shows the silane to have the stiffest puckering motion and the dibromide to be the least rigid.

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Section: Resultssupporting

confidence: 75%