Gas Electron Diffraction and Quantum-Mechanical Study of Dimethyloxalate
Authors: Vishnevskiy Yu.1; Ivanov A.1; Oberhammer H.1; Vilkov L.2
Source: Structural Chemistry, Volume 16, Number 1, February 2005 , pp. 41-46(6)
Publisher: Springer
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Abstract:
The geometrical structure and conformation of dimethyloxalate, CH3OC(O)–C(O)OCH3, have been studied by gas electron diffraction (GED) and quantum-chemical calculations (MP2 and B3LYP methods with 6-31G* and cc-pVTZ basis sets). The GED analysis with a dynamic model (T = 323 K) results in a mixture of two planar conformers, anti (C2h symmetry) and syn (C2v symmetry) orientation of the two C=O bonds. The energy difference between these conformers is 0.02(0.18) kcal/mol and barrier to internal rotation around the C–C bond is 0.44(0.41) kcal/mol. The CH3 groups occupy synperiplanar positions with respect to the C=O bonds. The following main geometrical parameters for the anti conformer (Å and degrees) have been derived: rg(C–C) = 1.532(3), rg(C=O) = 1.203(2), rg(Csp3–O) = 1.436(3), rg(Csp2–O) = 1.333(3),
(Csp2–Csp2–O) = 111.9(1.9), (Csp2–O–Csp3) = 116.3(1.6), (O–C= O) = 127.0(1.8).
Keywords: Dimethyloxalate; gas electron diffraction; ab initio and DFT calculations
Document Type: Research article
DOI: 10.1007/s11224-005-1079-y
Affiliations: 1: Department of Chemistry, Moscow State University, Moscow, 119899, Russia, 2: Department of Chemistry, Moscow State University, Moscow, 119899, Russia, Email: lvvilkov@phys.chem.msu.ru
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