Journal of Molecular Structure p. 1 - 8 (2011)
Update date:2022-08-11
Topics:
Bell, Stephen
Stidham, Howard D.
LaPlante, Arthur J.
Zheng, Ya Ying
Guirgis, Gamil A.
The infrared spectrum (3200-400 cm-1) of the gas and the Raman spectrum (3200-50 cm-1) of liquid and solid 1,1-difluoro-1- silacyclopentane and 1,1-dichloro-1-silacyclopentane have been recorded. In all of these physical states only the twisted (C2) conformer was detected. The conformational energies have been calculated with the Moller-Plesset perturbation method to the second order; MP2(Full) as well as the density functional theory by the B3LYP method utilizing a variety of basis sets up to 6-311 + G(2df,2pd). All the calculations predict only the twisted form as the stable conformer of 1,1-difluoro-1-silacyclopentane with the average barrier to planarity of 2548 cm-1 (30.49 kJ/mol) from the MP2 calculations and a significantly lower value of 1422 cm-1 (17.01 kJ/mol) from the density functional calculations. Neither calculation was significantly affected by the inclusion of diffuse functions. The Cs conformer has a lower energy of 1703 cm-1 (MP2) and 1334 cm -1 (B3LYP) than the planar form. Thus the path between the two identical C2 conformers is by pseudorotational motion rather than through the planar form. Similar results obtain for 1,1-dichloro-1- silacyclopentane. The optimized geometry calculated with the 6-311 + G(2df,2pd) basis is given together with a complete vibrational assignment for the twisted (C2) conformer. These assignments are supported by normal coordinate calculations with scaled force constants from MP2(Full)/6-31G(d) calculations. The results of these spectroscopic and theoretical studies are discussed and compared to the corresponding results for silacyclopentane.
View MoreAnhui Redstar Pharmaceutical Corp., Ltd
Contact:+86-563-5120837
Address:Jingxian Industrial Development Zone, Anhui , China
Ningbo Inno Pharmchem Co., Ltd.
Contact:86-574-87319282
Address:6F-5,NO.163 RUIQING RD.,NINGBO 315000 CHINA
Rugao Jinling Chemical Co., Ltd.
Contact:0086-513-68005586
Address:Lianluo new village huangshi town Rugao city Jiangsu Province.
Contact:+44 7958 511245
Address:PO Box 469, Manchester, UK
KINHENG CHEMICAL(SHANGHAI)CO., LTD.
Contact:+8621-60490170
Address:Room401, No.28,Lane 189, Yangshupu Rd. Shanghai, China.
Doi:10.1039/c4cp04241g
(2015)Doi:10.1021/ja01295a034
()Doi:10.1039/c8ce00021b
(2018)Doi:10.1021/acsmedchemlett.1c00071
(2021)Doi:10.1021/jf980949t
(1999)Doi:10.1021/ja01047a024
(1969)