FAR INFRARED SPECTRA OF ETHERS AND SOME BORON TRIHALIDE-AMINE COMPLEXES.
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Date
1965
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Ohio State University
Abstract
A Perkin-Elmer Model 301 Far Infrared Spectrophotometer has been used to record the far infrared spectra of aliphatic ethers and boron trihalide addition complexes. The ethers are of two types: (1) Saturated ethers: These include dimethyl, diethyl, di-n-propyl and diisopropyl ethers. (2) Unsaturated ethers: These include methyl vinyl, ethyl vinyl, isopropyl vinyl and isobutyl vinyl ethers. A high resolution spectrum of dimethyl ether was obtained with the Beckman IR-12. A normal coordinate analysis is in progress on this molecule and preliminary results show that the force constant for torsion about the C-C bond in ethane is transferable to the torsion about the C-O bond in dimethyl ether. Di-n-propyl ether (gas) has the following absorption bands below $550 cm^{-1}: 159.2$ (s), 221.9 (vvw), 272.1 (w), 323.2 (w), 410.5 (s), 460.7 (vw), 513.9 (s) 550 (wsh) $cm^{-1}$. Ethyl vinyl ether (gas) has the following absorption band centers: 245.7 (s, very complex structure), 329 (bw), about 335 (vw), 402.9 (s), 495 (w) $cm^{-1}$. All the ethers appear to display methyl torsional frequencies, which appear in the range $170-270 cm^{-1}$. Ethers with more than four carbon atoms show a strong absorption in the range $140 cm^{-1}$ to $200 cm^{-1}$. This may be a torsional frequency about the C-O bond; but skeletal modes will also have to be assigned in the range $150-300 cm^{-1}$. The far infrared spectra of $BF_{3}NH_{2}CH_{3}, BF_{3}NH(CH_{3})_{2}$ and $BF_{3}N(CH_{3})_{3}$ have been obtained. $BF_{3}NH_{2}CH_{3}$ (nujol mull) gave the following absorption bands: about 80 (w), 110 (bw), 212 (vw), 312 (sh), 353 (m), 471.2 (m), 541.8 (m) $cm^{-1}$. In addition, the PMR spectra of these complexes will be discussed. It appears that the methyl protons are coupled to the $^{11}$B atom with a $J_{11B; H3}$ of 2.1--1.5 cps.
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These studies are being supported by the MCA Research Project in the Department of Chemistry and by The Robert A. Welch Foundation, Houston, Texas.
Author Institution: Department of Chemistry, Texas A\&M University
Author Institution: Department of Chemistry, Texas A\&M University