MICROWAVE SPECTRUM HINDERED ROTATION POTENTIAL FUNCTION AND DIPOLE MOMENT IN 1-METHYLCYCLOPROPENE

The microwave spectrum of 1-methylcyclopropene (CH3-C3H3) has been observed in the ground and first excited torsional states. Thes A-level ground state rotational constants are A = 20,556.19 ± 0.09 MHz, B = 6356.98 ± 0.02 MHz, and C = 5176.42 ± 0.02 MHz. The first excited state A-level rotational constants are A = 20,322.35 ± 0.10 MHz, B = 6342.62 ± 0.02 MHz, and C = 5172.44 ± 0.02 MHz. The value of the first two terms in the hindered rotation potential function, determined from splittings in rotational transitions for the = 0 and v = 1 torsional states, are V3 = 1381 ± 2 cal/mole and V6 = 39 ±30 cal/mole. Analysis of the Stark effect yields molecular dipole moment components of µa = 0.818 ± 0.008 D and µb = 0.19 ± 0.02 D with the total moment H = 0.84 ± 0.01 D. © 1969, American Chemical Society. All rights reserved.