Journal of Molecular Structure p. 181 - 197 (2002)
Update date:2022-08-28
Topics:
Dakkouri, Marwan
Typke, Volker
The molecular structure of 1,1-dicyanocyclopentane (DCCP) has been investigated by means of gas-phase electron diffraction and ab initio calculation. Although the electron diffraction data could be fairly good reproduced by a Cs (envelope) model we found it more pertinent to apply a pseudorotation model to account for the dynamic and large amplitude motion in DCCP. Based on this model we analyzed the dependency of the ring geometric parameters and vibrational mean amplitudes on the phase angle φ. For a better elucidation of this distinct dependency we developed particular equations which describe the dependency of the distribution of the delocalized net charges throughout the ring on the phase angle φ. For the purpose of a more systematical study of the substituent effect exerted by the cyano group we also investigated the structure and conformational stability of monocyanocyclopentane (MCCP) by means of various quantum mechanical methods. The MP2 method in combination with the basis sets 6-311 + G(2df,2pd), 6-311 + G(d,p), and 6-31 G(d,p) favors the axial conformer which is in contradiction to earlier results which were obtained from electron diffraction data [J. Mol. Struct., 116 (1984) 29]. Using the same basis sets but the DFT/B3PW91 method, however, leads to a more stable equatorial conformer. This striking behavior is discussed in this paper. The joint electron diffraction and ab initio study has led to the following rα structural parameters of DCCP: r(C≡N) = 1.152(2) A?, r(C42≡) = 1.472(5) A?, average r(C-C)ring = 1.549(3) A?, ∠(C5-Cl-C2) = 103.6(26)°, ∠(NC-C-CN) = 109.0(35)°, ∠(C-C≡N) = 175.2(33)°, and ∠(H-C-H) = 112.7(23)°. The puckering amplitude for the five-membered ring was determined to be q = 0.434(45) A?. The quantum mechanical calculations were carried out by utilizing the Hartree-Fock, density functional B3PW91, and perturbation MP2 methods and applying the basis sets: 6-31 G(d,p), 6-311 G(df,pd), 6-311 + G(d,p) and 6-311 + + (2df,2pd). In contrast to the Mulliken poulation analysis the natural population analysis provided clear evidence for the electronic interaction and bond conjugation within the geminally substituted cyano groups.
View MoreContact:0572-2722882
Address:1201,F3,xinghuibandao,
Shanghai agrotree chemical co.,ltd.
Contact:+86-21-50117563
Address:Room 8A,liangfeng building,No.8 dongfang RD.pudong,shanghai,China
Henan zhongda Biological Engineering Co., Ltd
Contact:86-28-18109029985
Address:shenzhou road,xuedian industrial estate,zhengzhou city,henan province CHN
FUJIAN SHANSHUI CHEMICAL CORP.LTD.
Contact:+86-151-59920036
Address:Jinqiao Gareden, jo@fj-xinyi.com
Hebei Kangtai Pharmaceutical Co.,Ltd
Contact:+86-0317-3512963
Address:Wugang Road,Mengcun of Cangzhou City,Hebei Province ,China
Doi:10.1002/ejoc.201100189
(2011)Doi:10.1007/BF00664967
()Doi:10.1016/j.tetlet.2014.04.020
(2014)Doi:10.1021/acs.inorgchem.9b03476
(2020)Doi:10.1002/jps.2600681220
(1979)Doi:10.1021/acs.oprd.8b00089
(2018)