Bicorannulenyl: stereochemistry of a C40H18 biaryl composed of two chiral bowls.
The bicorannulenyl molecule is composed of two chiral bowls tethered by a single bond in a helical fashion. This simple combination of two chiral motifs gives rise to rich dynamic stereochemistry, where 12 conformers interconvert through bowl inversions and central bond rotation, and enantiomerizations occur via multistep processes. Interestingly, 8 out of 10 transition states are chiral, giving rise to mostly chiral enantiomerization pathways, where the molecule changes chirality without passing through an achiral conformation. However, analysis of the stereochemical landscape by DFT calculations and variable temperature NMR spectroscopy reveals that the energetically most favorable enantiomerization pathway passes through one of the two achiral transition states. Single-crystal X-ray diffraction corroborates the DFT results and provides information on packing modes of bicorannulenyl molecules in the solid state that have not been seen previously for other buckybowls.
Eisenberg
David
D
Institute of Chemistry and The Lise Meitner-Minerva Center for Computational Quantum Chemistry, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Filatov
Alexander S
AS
Jackson
Edward A
EA
Rabinovitz
Mordecai
M
Petrukhina
Marina A
MA
Scott
Lawrence T
LT
Shenhar
Roy
R