X-ray Crystal Structures of a Benzonorbornenyl Cation and of
a Protonated Benzonorbornenol<sup>†</sup>
Thomas Laube
10.1021/ja040115t.s003
https://acs.figshare.com/articles/journal_contribution/X_ray_Crystal_Structures_of_a_Benzonorbornenyl_Cation_and_of_a_Protonated_Benzonorbornenol_sup_sup_/3325690
The crystal structure of the 9-methylbenzonorbornenyl cation Me-<b>1</b><b><sup>+</sup></b><sup></sup> shows a relatively strong
interaction between the sp<sup>2</sup>-hybridized carbon atom C9 and the aromatic ring (C4a−C9 ≡ C8a−C9 =
1.897(10) Å). The anion Sb<sub>2</sub>F<sub>11</sub><sup>-</sup> is refined as rotationally disordered along the Sb···Sb axis. In sharp contrast
to the findings about Me-<b>1</b><b><sup>+</sup></b><sup></sup>, the protonated <i>anti</i>-benzonorbornenol <b>5</b><b><sup>+</sup></b><sup></sup> is essentially an oxonium ion with
only weak interaction between the C9 bridge and the aromatic ring despite the fact that it is already a
positively charged ion, which upon loss of a water molecule is expected to give the parent cation H-<b>1</b><b><sup>+</sup></b><sup></sup>.
The hydrogen atoms on the oxonium O atom are involved in strong hydrogen bonds to chlorosulfonate
anions and probably partially disordered despite the large estimated p<i>K</i><sub>a</sub> differences between the
corresponding acid−base pairs. The experimentally determined cation structures are compared with
structures computed by DFT methods. Detailed experimental procedures are given.
2004-09-08 00:00:00
crystal structure
cation structures
parent cation H
hydrogen atoms
chlorosulfonate anions
Benzonorbornenyl Cation
oxonium O atom
p K
hydrogen bonds
oxonium ion
DFT methods
anion Sb 2 F 11
interaction
hybridized carbon atom C 9
sp 2
water molecule
C 9 bridge
benzonorbornenol 5