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C 2 in a Box: Determining Its Intrinsic Bond Strength for the X 1 Σ g + Ground State
Author(s) -
Zou Wenli,
Cremer Dieter
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201503750
Subject(s) - triple bond , chemistry , bond strength , single bond , bond order , bond dissociation energy , bond length , chemical bond , atomic physics , ground state , sextuple bond , acetylene , bond energy , bent bond , quadruple bond , molecular geometry , molecule , dissociation (chemistry) , double bond , physics , alkyl , adhesive , organic chemistry , layer (electronics) , polymer chemistry
The intrinsic bond strength of C 2 in its 1 Σ g + ground state is determined from its stretching force constant utilizing MR‐CISD+Q(8,8), MR‐AQCC(8,8), and single‐determinant coupled cluster calculations with triple and quadruple excitations. By referencing the CC stretching force constant to its local counterparts of ethane, ethylene, and acetylene, an intrinsic bond strength half way between that of a double bond and a triple bond is obtained. Diabatic MR‐CISD+Q results do not change this. Confinement of C 2 and suitable reference molecules in a noble gas cage leads to compression, polarization, and charge transfer effects, which are quantified by the local CC stretching force constants and differences of correlated electron densities. These results are in line with two π bonds and a partial σ bond. Bond orders and bond dissociation energies of small hydrocarbons do not support quadruple bonding in C 2 .