Generation and Microwave Spectrum oftrans-1-Chloro-2-nitrosoethene, ClCH=CH—N=O

Abstract

trans-1-Chloro-2-nitrosoethene,[formula](synform:8in Fig. 1), has been generated in the gas phase from 1,1-dichloro-2-(hydroxyimino)ethane by pyrolysis or by chemical reaction of the precursor with NaHCO3and identified by microwave spectroscopy. The microwave spectrum has been observed in the frequency range from 8.0 to 40.0 GHz. The rotational constants (MHz) have been determined asA= 38935 (147),B= 1519.056 (6), andC= 1461.595 (6) for[formula](35Cl species) andA= 38 546 (81),B= 1481.667 (3), andC= 1426.835 (3) for[formula](37Cl species). The observed inertial defects of the35Cl and37Cl species were found to be −0.099 (51) and −0.003 (30) u Å2, respectively. The nuclear quadrupole coupling constants (MHz) were determined to be χaa= −50.4 (21) and χbb= 31.1 (63) MHz for the35Cl species, and χaa= −40.9 (10) and χbb= 27.7 (22) MHz for the37Cl species. One vibrationally excited state was observed and assigned to the C–N torsional mode [120 (30) cm−1] that was almost harmonic. The observed pyrolysate was determined to betrans-1-chloro-2-nitrosoethene by comparing the observed and calculated rotational constants and coordinates of the chlorine atom. Ther0structural parameters of[formula]and[formula]and bond angle of[formula]were determined by fitting them to the observed rotational constants. Interesting reaction products, such as formyl chloride and hydrogen cyanide, were also detected during the pyrolysis of the precursor. The lifetime oftrans-1-chloro-2-nitrosoethene is ca. 1 min in the waveguide cell.