Isomers of SNO2: Production and infrared spectra of cis- and trans-OSNO from irradiated inert matrices containing OCS and NO2

New species cis- and trans-OSNO, designated c-OSNO and t-OSNO, respectively , are produced and identified with infrared absorption spectra when an argo n or nitrogen matrix containing OCS and NO2 is irradiated with laser emissi on at 248 nm. Lines at 1156.1 and 1454.4 cm(-1) are assigned to c-OSNO and those at 1178.0 and 1459.0 cm(-1) are assigned to t-OSNO in solid N-2. Line s at 1154.9 and 1450.8 cm(-1) are assigned to c-OSNO and those at 1181.2 an d 1456.0 cm(-1) are assigned to t-OSNO in solid Ar; further lines associate d with minor matrix sites are identified. Assignments of spectral lines are based on results of both experiments with N-15- and O-18-isotopic substitu tion and theoretical calculations using density-functional theories, B3LYP with an aug-cc-pVTZ basis set; these calculations predict the geometry, ene rgy, vibrational frequencies, and infrared intensities of SNO2 as four isom ers: C-2v-SNO2, t-SONO, t-OSNO, and c-OSNO, in increasing order of stabilit y. Mechanisms are proposed to rationalize that c-OSNO and t-OSNO, rather th an t-SONO or C-2v-SNO2, are produced from irradiated matrices containing OC S and NO2, and that no reaction product is observed in an Ar matrix contain ing CS2 and NO2 after irradiation at 193 nm. (C) 2001 American Institute of Physics.