THE HYDROXYETHYNYL RADICAL (CCOH) - AN ACCESSIBLE ISOMER OF THE KETENYL RADICAL (HCCO)

The two lowest-lying states ((X) over tilde(2)A '' and (A) over tilde( 2)A') of the hydroxyethynyl radical (CCOH), an isomer of the ketenyl r adical (HCCO), have been investigated theoretically using ab initio el ectronic structure theory. The ground and first excited electronic sta tes of CCOH were determined to have trans-planar bent structures. At t he TZ3P(2f,2d) CCSD(T) level of theory the two lowest-lying states of CCOH were predicted to lie 54.2 kcal/mol (2.35 eV, 19000 cm(-1)) and 6 5.8 kcal/mol (2.85 eV, 23000 cm(-1)) classically above the ground stat e of HCCO. Due to its large dipole moments and significantly large vib rational infrared (IR) intensities, the CCOH radical may be suitable f or microwave and IR spectroscopic investigations. (C) 1998 Elsevier Sc ience B,V. All rights reserved.