IODO- AND FLUOROPENTABORANES . NUCLEAR MAGNETIC RESONANCE COMPARISON OF 2-PENTABORANE(9) DERIVATIVES

被引:37
作者
BURG, AB
机构
[1] Department of Chemistry, University of Southern California, Los Angeles
关键词
D O I
10.1021/ja01008a006
中图分类号
O6 [化学];
学科分类号
0703 ;
摘要
Pentaborane(9) derivatives of the type 1-XB5H8 are more stable when X = heavier halogen, whereas 2-XB5H8 compounds are more stable when X = lighter halogen. The reason may be found in the different π-type interactions with the B5 cage, and similar ideas explain some otherwise anomalous UB nmr chemical shifts. The catalytic isomerization of 1-IB5H8 to the far less stable new isomer 2-IB5H8 (mp -39°; bp 167° est) requires steady removal of this more volatile product. It is argued that halogen exchanges on the B5 skeleton are done best by gas-flow processes at minimal pressure, as when HgCl2 converts 1-IB5H8 to 1-C1B5H8 or SbF3 converts 2-IB5H8 to the new 2-FB5H8 (mp —63°; bp 71° est). However, the analogous synthesis of 1-FB5H8 gave a product too unstable to be isolated. The 11B nmr comparisons include all four of the 2-halogenated pentaboranes and 2-CH3-B5H8, and accurate vapor-phase infrared spectra are reported for the five known XB5H8 compounds not previously so recorded. © 1968, American Chemical Society. All rights reserved.
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页码:1407 / &
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