Knowledge Bank

Fourier transform infrared studies have resulted in the first observation of vibrational spectra of the linear SiCH and nonplanar $H2SiCCH$ radicals produced by trapping the products of the vacuum ultraviolet photolysis of a mixture of $SiH4$ silane, and $C2H2$ acetylene, in an Ar matrix at about 10 K. The silicon-carbon stretching mode $\nu 1(\sigma )$ of SiCH has been observed at $1010.4cm-1$. Two vibrational fundamentals of $H2SiC2H$ have been identified, the $v3(a\prime )$, silicon-carbon stretching mode at $2055.6cm-1$ and the $v4(a\prime )$, hydrogen-silicon bending mode at $926.8cm-1$. The results of extensive measurements of D and $\mathrm{<mrow\; data-mjx-texclass="ORD">13</mrow>}C$ isotopic shifts are in good agreement with the predictions of coupled cluster ab initio calculations performed at the CCSD(T)/6-$31G\ast \ast$ level and confirm the proposed identifications.