A Stacking Interaction between a Bridging Hydrogen Atom and Aromatic π Density in the n-B18H22–Benzene System
✍ Scribed by Ewan J. M. Hamilton; Roman G. Kultyshev; Bin Du; Edward A. Meyers; Shengming Liu; Christopher M. Hadad; Sheldon G. Shore
- Publisher
- John Wiley and Sons
- Year
- 2006
- Tongue
- English
- Weight
- 270 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
Abstract
The structures of n‐B~18~H~22~ and of n‐B~18~H~22~⋅C~6~H~6~ were determined by single‐crystal X‐ray analysis at −60 °C. The geometry of the boron cluster itself does not seem to be appreciably affected by solvation. There does, however, appear to be an unusual interaction of a polyborane bridging hydrogen atom with the benzene π system, giving rise to an extended stacked structure. The ^1^H{^11^B} spectrum of n‐B~18~H~22~ in [D~6~]benzene differs from that in [D~12~]cyclohexane most noticeably in the bridging proton region. Upon moving from the aliphatic to the aromatic solvent, the greatest increase in shielding was for the signal corresponding to the bridge hydrogen atom that interacts with the π system of benzene; the signal was shifted upfield by 0.49 ppm. Density functional theory calculations were performed on 1:1 and 2:1 complexes of the n‐B~18~H~22~ unit with benzene.