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Unusually Short Be−Be Distances with and without a Bond in Be 2 F 2 and in the Molecular Discuses Be 2 B 8 and Be 2 B 7 −
Author(s) -
Cui Zhonghua,
Yang Wensheng,
Zhao Lili,
Ding Yihong,
Frenking Gernot
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201601890
Subject(s) - beryllium , crystallography , molecule , chemistry , bond length , atoms in molecules , chemical bond , single bond , hypervalent molecule , atomic physics , bond dissociation energy , bond order , physics , crystal structure , group (periodic table) , organic chemistry , reagent
Quantum‐chemical calculations at the CCSD(T)/cc‐pVTZ level of theory show that beryllium subfluoride, Be 2 F 2 , has a bond dissociation energy of D e =76.9 kcal mol −1 , which sets a record for the strongest Be−Be bond. The synthesis of this molecule should thus be possible in a low‐temperature matrix. The discus‐shaped species Be 2 B 8 and Be 2 B 7 − possess the shortest Be–Be distance for a molecule in the electronic ground state, but there is no Be−Be bond. The cyclic species Be 2 B 8 and Be 2 B 7 − exhibit double aromaticity with 6σ and 6π electrons, which strongly bind the Be 2 fragment to the boron atoms. The very short interatomic distance between the beryllium atoms is due to the Be−B σ and π bonds, which operate like spokes in a wheel pressing the beryllium atoms together. The formation of the Be−B bonds has effectively removed the electronic charge of the valence space between the beryllium atoms. Along the Be–Be axis, there are two cage critical points adjacent to a ring critical point at the midpoint, but there is no bond critical point and no bond path.