THE ELECTRONIC-STRUCTURE OF CIS-DECALIN AND TRANS-DECALIN RADICAL CATIONS IN HALOCARBON MATRICES - AN ESR AND MNDO STUDY

The ESR spectra of radical cations of cis- and trans-decalin have been recorded in different halocarbon matrices within the temperature range 4.2 to 130 K. The ground-state structures of both isomers have been calculated using the UHF/MNDO technique and found to be 2Ag or 2Bg for trans-decalin+ and 2A1 or 2B1 for cis-decalin+, respectively. Calculated hyperfine splittings were found to be in good agreement with experiments. In contrast to cis-decalin+ where only the 2A1 state was observed in the experiments, the electronic ground state of trans-decalin+ has been shown to depend on the matrix and to be either 2Ag or 2Bg. In the perfluoromethylcyclohexane and CF2ClCFCl2 matrices both these states of trans-decalin+ were observed at 4.2 K. The ESR spectrum of trans-decalin+ observed in these matrices at 77 K corresponds to a rapid exchange between the 2Ag and 2Bg states. © 1990.