1228384-07-3Relevant academic research and scientific papers
Phenylhydroxycarbene
Gerbig, Dennis,Reisenauer, Hans Peter,Wu, Chia-Hua,Ley, David,Allen, Wesley D.,Schreiner, Peter R.
, p. 7273 - 7275 (2010)
Phenylhydroxycarbene (Ph-C-OH, 1), the parent of all arylhydroxycarbenes, was generated by high-vacuum flash pyrolysis of phenylglyoxylic acid at 600 °C and spectroscopically characterized (IR, UV-vis) via immediate matrix isolation in solid Ar at 11 K. The identity of 1 was unequivocally confirmed by the precise agreement between the observed IR bands and (unscaled) anharmonic vibrational frequencies computed from a CCSD(T)/cc-pVDZ quartic force field. The UV-vis spectrum of 1 displays a broad band with maximum absorption at 500 25 nm (2.5 ± 0.1 eV) that extends to ～640 nm (1.9 eV), in full accord with combined CCSD(T)/cc-pVQZ and EOM-CCSD/cc-pVTZ computations that yield a gas-phase vertical (adiabatic) excitation energy of 2.7 (1.9) eV. Unlike singlet phenylchlorocarbene, 1 does not undergo photochemical ring expansion. Instead, 1 exhibits quantum-mechanical hydroGenetunneling to benzaldehyde underneath a formidable barrier of 28.8 kcal mol-1, even at cryogenic temperatures. The remarkable hydroGenetunneling mechanism is supported by the temperature insensitivity of the observed half-life (2.5 h) and substantiated by a comparable theoretical half-life (3.3 h) determined from high-level barrier penetration integrals computed along the intrinsic reaction path. As expected, deuteration turns off the tunneling mechanism, so d-1 is stable under otherwise identical conditions.
