Coupled cluster study of the phenyl-acetylide anion

Using coupled cluster theory with singles and doubles substitutions (CCSD) we have characterized the ground-state geometry and electronic structure of the phenyl acetylide anion (1) which has been recently isolated and characterized by NMR spectroscopy [Y. Tanaka et al., Chem. Asian. J. 1 (2006) 581]. Calculations indicate the bond in the acetylide moiety being an elongated triple carboncarbon bond which becomes strengthened upon interaction with the Li+ ion. Fluorine substitution stabilizes the carbanion, as testified by the increase in the HOMO–LUMO energy gap. Minor structural problems encountered with the DFT-optimized geometries are also discussed.