Matrix isolation study of ethyl chloroformate, ClC(O)OCH2CH3

The FTIR spectra of the syn-anti and syn-gauche forms of ethyl chloroformate, ClC(O)OCH2CH3, isolated in solid argon or nitrogen, were presented and completely assigned. Photolysis of the matrixes with broad band UV–visible radiation results in a decrease of the intensities of the IR absorptions assigned to the most stable syn-anti conformer while the corresponding to the less stable syn-gauche form increase their intensities. Besides the randomisation process, no changes were observed in the matrix spectra upon irradiation. The IR spectra of the two conformers were simulated using DFT methods (B3LYP/6–311++G**), and the predicted conformational ratio was 62% of the syn-anti form and 38% of syn-gauche conformer.