TUNNELING IN DIBORANE-HYDROGEN CHLORIDE DIMERS$^{\ast}$
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Date
1987
Authors
Chuang, C.
Klots, T. D.
Ruoff, R. S.
Emilsson, T.
Gutowsky, H. S.
Journal Title
Journal ISSN
Volume Title
Publisher
Ohio State University
Abstract
K = 0 transitions have been assigned in the microwave rotational spectra for six isotopic variations of the $B_{2}H_{6}-HCl$ dimer. The homonuclear dimens, with $^{1}B-{^{11}}B$ and $^{10}B-{^{10}}B$, have tunneling splittings of several MHz, while the mixed species with $^{10}B-{^{11}}B$ and $^{11}B-{^{10}}B$ show no tunneling. This contrasts with $B_{3}H_{6}-H_{F}$ which has a torsionally averaged, linear B-B-F structure with no evidence of $tunneling.^{1}$ The line center of the $^{11}B{^{11}}B-H{^{35}}Cl J = 3 \to 4, K = 0$ transition is at 10 186.777 MHz. The splitting due to tunneling is 2.587 MHz, a value which decreases somewhat for both lower and higher J. In the $^{11}B{^{11}}B-H{^{37}}Cl$ species the splitting for $J = 3 - 4$ decreases to 2.325 MHz while that in $^{10}B{^{10}}B-H{^{35}}Cl$ is 4.726 MHz. This indicates that the tunneling motions involve both subunits. Work is in progress to locate the $K = \pm 1$ transitions so that accurate rotational constants and the structure can be deduced. The results so far indicate a near linear H-B-Cl configuration.
Description
$^{\ast}$ Work supported by NSF and PRF. $^{1}$ H.S. Gutowsky, T. Emilsson, J.D. Keen, J.D. Klots, and C. Chuang, J. Chem. Phys. 85, 683 (1986).
Author Institution: Noyes Chemical Laboratory, University of Illinois
Author Institution: Noyes Chemical Laboratory, University of Illinois