ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
The structures and optical spectroscopy of the CHFCl radical and cation were studied by ab initio molecular orbital calculations and by experiment. Ab initio calculations at the MP2/ 6–311++G** theory level found that the optimum structure of the CHFCl+ (X˜ 1A') cation is planar with r(C–H)=1.092 A(ring), r(C–F)=1.254 A(ring), r(C–Cl)=1.599 A(ring), (angle)H–C–F=116.85°, and (angle)H–C–Cl=122.14°. CHFCl (X˜ 2A') radical is nonplanar with r(C–H)=1.083 A(ring), r(C–F)=1.335 A(ring), r(C–Cl)=1.705 A(ring), (angle)H–C–F=113.49°, (angle)H–C–Cl=116.68°, and (angle)F–C–Cl=114.44°. The ab initio angle between the F–C–Cl plane and the C–H bond is Φe=38° and the inversion barrier is Binv=1190 cm−1. Using isogyric reactions to obtain empirical corrections, we calculate IPa(CHFCl)=8.37±0.05 eV. Ab initio vibrational frequencies are reported. The electronic spectrum of the CHFCl radicals was observed between 340–420 nm using one color, mass resolved, 2+1 resonance enhanced multiphoton ionization (REMPI) spectroscopy. The spectrum arises from two-photon resonances with the planar F˜(3p) [λlaser=406.7 nm, ν00=49 160(20) cm−1] and J(3d) [λlaser=361.9 nm, ν00=55 250(20) cm−1] Rydberg states. A third laser photon ionized the radicals. Both states produced the same vibrational constants: ν2 (C–H deformation)=1280(30) cm−1, ν4 (C–Cl stretch)=910(30) cm−1, ν5 (CFCl scissors)=440(30) cm−1, ν6 (OPLA)=980(30) cm−1. The REMPI spectrum exhibited v‘6 = 1–6 hot bands of the CHFCl (X˜ 2A) radical. Modeling of these hot bands with a double-well potential gives the inversion barrier, Binv=1180 cm−1, and Φe=42°.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.464226
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