Microwave spectrum, structure, dipole moment and excited states of (CH3)3CCP

Abstract

The microwave spectra of four isotopic species of (CH₃)₃CCP have been studied in the frequency range 9–40 GHz. The zero-point average structure has been determined for the heavy atoms to be: r(C₁P)= 1.543(3)Å, r(C₂—CP)= 1.478(3)Å and r(C₂—C₃[methyl])= 1.544(3)Å with ∠ C₁—C₂—C₃= 109.2(1)°. The ground-state dipole moment has been determined to be 1.486(3) D (1 D = 3.335 64 × 10^–30 C m) from Stark-effect measurements. Two prominent vibrational satellite series have been assigned. The lowest bending vibration is determined to have a wavenumber of 140(10) cm^–1 from the l-type doubling constant q= 1.474(4) MHz, in agreement with relative intensity measurements corrected for the effects of l-type doubling and resonance.