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Benzdiynes revisited: ab initio and density functional theory
Author(s) -
Arulmozhiraja Sundaram,
Sato Tadatake,
Yabe Akira
Publication year - 2001
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.1055
Subject(s) - density functional theory , ab initio , thermodynamics , computational chemistry , chemistry , valence (chemistry) , standard enthalpy of formation , physics , organic chemistry
Ab initio and density functional theory (DFT) studies were performed on three isomers of tetradehydrobenzene (benzdiynes). Four different density functionals (BPW91, BLYP, B3LYP, and B1LYP) and two higher levels of theory [QCISD and CCSD(T)] incorporating basis sets up to Dunning's correlation‐consistent polarized valence triple‐ζ (cc‐pVTZ) were utilized for this purpose. Stability tests showed that more stable solutions were available for 1,4‐benzdiyne with unrestricted than with restricted DFT, while solutions obtained with later descriptions of 1,3‐benzdiyne and 1,2,3,5‐tetradehydrobenzene were stable. UB3LYP provided better geometry for 1,4‐benzdiyne. Unlike in an earlier study, the energy difference between 1,2,3,5‐tetradehydrobenzene and 1,4‐benzdiyne calculated with the B3LYP functional coincided well with that calculated at CCSD(T): 13.07 and 14.32 kcal/mol at the B3LYP/cc‐pVTZ and CCSD(T)/cc‐pVTZ levels, respectively. 1,2,3,5‐Tetradehydrobenzene was 8 kcal/mol more stable than 1,3‐benzdiyne at the CCSD(T)/cc‐pVTZ level. The heats of formation of benzdiynes were obtained by using the G2, CBS‐Q, and CBS‐QB3 methodologies. The heats of formation calculated for 1,3‐benzdiyne and 1,2,3,5‐tetradehydrobenzene were 208.6 and 197.9 kcal/mol, respectively, at the CBS‐QB3 level of theory. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 923–930, 2001