INFRARED-ABSORPTION OF CYCLIO-NANO2 AND TRANS-NANO2 AND KNO2 IN SOLIDARGON

Sodium nitrite dispersed in solid argon exhibited infrared absorption at 1293.0, 1222:8, and 825.6 cm-1, corresponding, respectively, to sym metric and asymmetric stretching, and bending, modes of cm the NO2- mo iety in a bidentate planar cyclic structure of C-2 upsilon symmetry (d esignated cyclic-NaNO2). After irradiation of the matrix sample with e mission from the KrF laser at 248 nm, new lines at 1446.2, 1159.1, and 787.1 cm(-1) were recorded. A sample containing (NaNO2)-N-15 absorbed at 1272.1, 1198.2, and 821.7 cm(-1) before irradiation; new lines at 1419.6, 1136.9, and 782.81 cm(-1) were observed after irradiation. New lines observed after irradiation are assigned to sodium nitrite with a monodentate planar trans structure (designated trans-NaNO2). Ab init io calculations according to density functional theory at Becke3LYP/6- 311+G level predicted line positions, isotopic shifts, and relative I R intensities similar to those observed experimentally for both isomer s. Similar results were obtained for cyclic-KNO2 at (1313.4, 1310.8), (1217.3, 1207.9), and (807.2, 809.5) cm(-1) before irradiation, and fo r trans-KNO2 at (1412.4, 1413.2), (1171.0, 1178.2, 1176.4), and 783.1 cm(-1) after irradiation at 248 nn; the numbers grouped in parentheses reflect link splitting. (C) 1996 American Institute of Physics.