Microwave spectra of trimethylsilylethyne, Me3SiC CH, 1-cyano-2-trimethylsilylethyne, Me3SiC CC N, and 1-cyano-4-trimethylsilylbutadiyne, Me3Si(C C)2C N
Abstract
The microwave spectra of the title compounds, recorded in the 26.5–40.0 GHz region, are characteristic of symmetric top molecules, complicated by internal rotation and accompanied by vibrational satellites attributed to low-frequency skeletal bending modes. For Me3SiC CH, B0= 1962.163 MHz and relative intensity measurements on the vibrational satellites give a value of 110 ± 15 cm–1 for the degenerate Si—CC bending mode. Measurements on Me3SiC CD have been made, and the Si—C bond length has been determined as 1.83 ± 0.01 Å. For Me3SiC CC N, B0= 711.8646 MHz, whilst for Me3Si(CC)2CN, twenty broad-band symmetric-top transitions, from J= 41 to 60, have been observed and a B value of 331 ± 2 MHz has been estimated.