Microwave Spectrum of Bromocyclobutane

TLDR: In this paper, the rotational transitions of four isotopic species of bromocyclobutane have been observed, and a set of structural parameters which reproduce these constants within 1.8 Mc were obtained with an electronic computer.

Abstract: Rotational transitions of four isotopic species of bromocyclobutane have been observed. For C4H7Br79, [Complex chemical formula] or [Complex chemical formula] the rotational constants are A = 10 003.4±13 Mc, B = 1629.41±0.03 Mc, C = 1488.48±0.03 Mc; for C4H7Br81, A = 10 002.6±13 Mc, B = 1615.14±0.03 Mc, and C = 1476.50±0.03 Mc. The values for the α‐deuterated compound are, for C3H6CDBr79, A = 9534.7±13 Mc, B = 1613.67±0.03 Mc, and C = 1486.24±0.03 Mc; for C3H6CDBr81, A = 9533.4±13 Mc, B = 1599.55±0.03 Mc, and C = 1474.24±0.03 Mc. A set of structural parameters which reproduce these constants within 1.8 Mc were obtained with an electronic computer: bond distances Cα–Cβ = 1.540±0.003 A, Cβ–Cγ = 1.548±0.003 A, C–Br = 1.939 A, C–H = 1.096 A, and C—D = 1.087 A; bond angles CβCγCβ = 88° 06′±08′, CβCαCβ = 88°41′±08′, HCγH = 110°44′, HCβH = 108°44′, HCαBr = 111°, angle of CβCαCβ plane with C–Br = 131°00′±08′, and dihedral angle = 29°22′±08′ (the dihedral angle is the angle made by the normals of the CβCαCβ and Cβ...