Electronic spectroscopy of monohalogenated carbenes
Abstract
The work presented in this dissertation--the thorough characterization of the Ã1 A" level of the monohalocarbenes CDF, CHBr and CDBr--is an essential step towards the determination of the singlet-triplet energy gap in carbenes, which in turn is central to the understanding of their chemistry. We surveyed the visible region recording fluorescence excitation spectra of the three monohalocarbenes. Subsequently, we rotationally analyzed cold bands in the pure bending progressions and combination bands involving the C--H(D) stretch and/or C--F or C--Br stretch, in addition to a number of hot bands. The analysis yielded band origins and effective rotational constants B¯' for the singlet excited state in all three cases, as well as A' rotational constants for a number of bands in CDF. We also derived barriers to linearity and gathered information about the onset of the Renner-Teller effect. We examined the isotope shift in the Ã1A" [arrow left] X 1A' system of CH(D)Br and estimated the C--H(D) and C--Br stretching frequencies. Where they overlapped, our results were in excellent agreement with theoretical predictions.
This paper has been withdrawn.