Open AccessLong Carbon–Carbon Bonding beyond 2 Å in Tris(9-fluorenylidene)methane
Author(s) -
Takashi Kubo,
Yuki Suga,
Daisuke Hashizume,
Hiroki Suzuki,
Tatsuya Miyamoto,
Hiroshi Okamoto,
Ryohei Kishi,
Masayoshi Nakano
Publication year - 2021
Publication title -
journal of the american chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.115
H-Index - 612
eISSN - 1520-5126
pISSN - 0002-7863
DOI - 10.1021/jacs.1c07431
Subject(s) - chemistry , homo/lumo , diradical , molecular orbital , atomic orbital , covalent bond , orbital overlap , non bonding orbital , carbon fibers , methane , crystallography , molecular physics , electron , photochemistry , atomic physics , molecule , organic chemistry , physics , materials science , quantum mechanics , composite number , singlet state , composite material , excited state
We report on our investigation of C-C bonding longer than 2.0 Å, which can be realized by perpendicularly facing two fluorenyl rings in the title compound. A small orbital overlap between the distantly positioned carbon atoms is observed as a small concentration of electrons on the X-ray electron density map. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the compound originate from the in-phase and out-of-phase interactions of the overlapping orbitals, respectively, with a gap of 2.39 eV. Solid-state 13 C NMR spectroscopy shows a sharp peak at 82.9 ppm for the long-bonded carbons, and a CASSCF(6,6) calculation indicates small diradical character. The experimental and theoretical analyses reveal sufficient covalent-bonding interaction in the long-bonded carbon pair.
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