The microwave spectrum and conformations of halomethyl oxiranes: Bromomethyl oxirane

Abstract The microwave spectrum of bromomethyl oxirane has been recorded in the range 12.5–18 and 26.5–40 GHz. Lines of the two bromine isotopic species of three rotamers, gauche -1 (Br near the O atom), gauche -2 (Br near the CH 2 of the ring) and cis have been identified. The gauche -1 lines are strongest, and the cis lines the weakest. The rotational constants (in MHz) are: gauche -1 ( 79 Br) A = 12 296.050, B = 1 391.677, C = 1 317.360, ( 81 Br) A = 12 199.162, B = 1 378.321, C = 1 309.142; gauche -2 ( 79 Br) A = 12 278.436, B = 1 378.830, C = 1 304.852, ( 81 Br) A = 12 189.869, B = 1 369.696, C = 1 301.584; cis ( 79 Br) A = 7 733.314, B = 1 808.087, C = 1 737.340, ( 81 Br) A = 7 726.16, B = 1 801.159, C = 1 730.125.