Photochemistry of iodoform in methanol: formation and fate of the iso-CHI2-I photoproduct.
Ultrafast population and structural dynamics due to the iso-CHI(2)-I isomer product formed upon UV excitation of iodoform (CHI(3)) in solution is monitored by femtosecond transient absorption with deep-UV through near-IR probing and picosecond transient resonance Raman spectroscopy. Iso-CHI(2)-I is found to be a major photochemical product regardless of excitation wavelength (266 and 350 nm) and choice of solvent (methanol, acetonitrile, and cyclohexane), and is produced in 50% quantum yield upon 266 nm excitation of CHI(3) in CH(3)OH. The isomer remains stable up to at least several nanoseconds in C(6)H(12) and CH(3)CN, but undergoes decay with a 740 ps lifetime in CH(3)OH simultaneously with the formation of an iodide ion. In agreement with the experiments, MP2 calculations suggest that iso-CHI(2)-I readily reacts with CH(3)OH via O-H insertion/HI elimination reactions.
Department of Chemistry, Center for Photochemical Sciences, Bowling Green State University, Bowling Green, OH 43402, USA.
Patrick Z
PZ
El-Khoury
Wai Ming
WM
Kwok
Xiangguo
X
Guan
Chensheng
C
Ma
David Lee
DL
Phillips
Alexander N
AN
Tarnovsky