Unusually Short Be-Be Distances with and without a Bond in Be2 F2 and in the Molecular Discuses Be2 B8 and Be2 B7 (.).
Quantum-chemical calculations at the CCSD(T)/cc-pVTZ level of theory show that beryllium subfluoride, Be2 F2 , has a bond dissociation energy of De =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 Be2 B8 and Be2 B7 (-) possess the shortest Be-Be distance for a molecule in the electronic ground state, but there is no Be-Be bond. The cyclic species Be2 B8 and Be2 B7 (-) exhibit double aromaticity with 6σ and 6π electrons, which strongly bind the Be2 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.
Institute of Theoretical Chemistry, Jilin University, Changchun, 130023, P.R. China.|College of Chemistry, Jilin University, Changchun, 130012, P.R. China.
Zhong-Hua
ZH
Cui
College of Chemistry, Jilin University, Changchun, 130012, P.R. China.
Wen-Sheng
WS
Yang
Fachbereich Chemie, Philipps-Universität Marburg, 35032, Marburg, Germany. lili.zhao@staff.uni-marburg.de.
Lili
L
Zhao
Institute of Theoretical Chemistry, Jilin University, Changchun, 130023, P.R. China. yhdd@jlu.edu.cn.
Yi-Hong
YH
Ding
Fachbereich Chemie, Philipps-Universität Marburg, 35032, Marburg, Germany. frenking@chemie.uni-marburg.de.|Donostia International Physics Center (DIPC), P.K. 1072, 20080, Donostia, Euskadi, Spain. frenking@chemie.uni-marburg.de.
Gernot
G
Frenking
aromaticity; beryllium subfluoride; bonding analysis; boron