MICROWAVE SPECTRUM AND STRUCTURE OF THE 2,6-DIFLUOROPYRIDINE-CO$_{2}$ COMPLEX
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Date
2013
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Publisher
Ohio State University
Abstract
The microwave spectrum of the weakly bound complex formed from 2,6-difluoropyridine and CO$_{2}$ has been obtained using the Amherst broadband microwave spectrometer. Preliminary analysis indicates a structure in which the nitrogen of the 2,6-difluoropyridine is directed toward the carbon of the CO$_{2}$. However, unlike the related complex pyridine-CO$_{2}$, which is planar, the CO$_{2}$ is rotated out of the plane of the heterocycle. The nitrogen-carbon van der Waals distance is 2.916 \AA, significantly larger than the 2.7977(64) \AA\ value previously reported for pyridine-CO$_{2}$. \emph{Ab initio} calculations at the MP2/6-311++G(2d,2p) level support a nitrogen bound geometry, but indicate an equilibrium structure in which the CO$_{2}$ lies off the C$_{2}$ axis of the 2,6-difluoropyridine. One dimensional discrete variable representation (DVR) calculations using an \emph{ab initio} potential restricted to rotation of CO$_{2}$ about the C$_{2}$ axis of the difluoropyridine indicate that the complex is in the high-barrier limit to internal rotation and that no splittings due to internal rotation will be observed in the spectrum.
Description
Author Institution: Department of Chemistry, University of Minnesota, 207 Pleasant St., SE, Minneapolis, MN 55455; Department of Chemistry, Amherst College, P.O. Box 5000, Amherst, MA 01002-5000; Department of Chemistry, University of Minnesota, 207 Pleasant St., SE, Minneapolis, MN 55455