Spectroscopy of "invisible" alkylchlorocarbenes: Dynamics and solvent interactions

ORGN 451

Robert A. Moss, moss@rutchem.rutgers.edu, Jingzhi Tian, Karsten Krogh-Jespersen, and Ronald R. Sauers. Department of Chemistry & Chemical Biology, Rutgers University, 610 Taylor Road, Piscataway, NJ 08854
Contrary to implications in the literature, the sigma to p absorptions of alkychlorocarbenes (RCCl) are readily acquired by laser flash photolysis with UV-vis detection in solution at ambient temperature. Examples include RCCl with R = methyl, benzyl, t-butyl, 1-adamantyl, and cyclopropyl. These absorptions permit direct monitoring of carbene reactions and the formation of carbene-solvent complexes. The kinetics of the reactions of ‘free' and complexed methylchlorocarbene and benzylchlorocarbene were directly followed with tetramethylethylene and 1-hexene. Particularly effective complexation was provided by anisole and 1,3-dimethoxybenzene, which modulated the rates of intermolecular carbene additions. Computational studies are presented which aid in understanding the carbene absorption spectra and the nature of the solvent complexes.