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1998-FD-03.jpg 132.4Kb JPEG image Thumbnail of A MICROWAVE STUDY OF PARTIALLY BOUND $H_{2}O-BF_{3}$

Creators: Ott, M. E.; Fiacco, D. L.; Howe, T.; Reeve, S. W.; Cramer, C. J.; Leopold, K. R.
Issue Date: 1998
Publisher: Ohio State University
Abstract: We report the microwave spectrum and structure of the partially bonded donor - acceptor adduct $H_{2}O-BF_{3}$. $H_{2}O$ and $BF_{3}$ react to form two compounds, a monohydrate and a dihydrate, both with well defined stoichiometries and melting points. For the monohydrate, previous X-ray diffraction $work^{a}$ indicates a B-O bond distance of 1.532 {\AA} (equal to the sum of covalent radii) and a tetrahedral geometry at the boron. In the gas, however, we find a bond length of 1.90 {\AA} and an out-of-plane distortion of the $BF_{3}$ of only $8^{\circ}$. Thus, while the B-O bond in the solid is an ``ordinary'' dative linkage, the bond in the gas phase system appears to be only partially developed. The large changes in bond length and bond angle which occur upon crystallization (0.4 {\AA} and $9^{\circ}$, respectively) will be discussed in comparison with other partially bound systems which have been investigated in our laboratory. Ab initio calculations place the gas phase binding energy at 9.6 kcal/mol, which is a very reasonable value for a partially formed dative bond.
Description: $^{a}$ Von D. Mootz and M. Steffen Z. Anorg. Allg. Chem. 483, 171, 1981.
Author Institution: Department of Chemistry, University of Minnesota; Department of Chemistry and Biochemistry, Arkansas State University; Department of Chemistry, University of Minnesota
URI: http://hdl.handle.net/1811/18771
Other Identifiers: 1998-FD-03
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