Microwave spectrum, average structure and dipole moment of 1-chloropropyne, CH3C CCl

Abstract

The microwave spectrum of 1-chloropropyne, CH₃C CCl, has been reinvestigated in the frequency range 8–41 GHz. Previous ambiguities in the ground-state centrifugal distortion constants have been removed. Microwave data for ten isotopomers have been used to calculate the zero-point average structure after the necessary vibrational corrections:

r(CC)= 1.201(2)Å, r(C—C)= 1.461(1)Å, r(C—Cl)= 1.643(2)Å, ∠HCH = 108.4(2)°, r(C—H)= 1.103(5)Å

The ground-state dipole moment has been determined to be 1.409(3) D (1D ≈ 3.335 64 × 10^–30C m) from Stark-effect measurements. The vibrational satellite series from the lowest degenerate bending mode ν₁₀ has been assigned. For V₁₀= 1/-type doubling has been measured, giving q₁₀= 2.029 (5) MHz which gives the wavenumber of ν₁₀ to be 184(8) cm^–1.