Silaethene H₂CSiH₂: Millimeter Wave Spectrum and Ab Initio Calculations

Abstract

139 rotational lines of the 28 Si isotopomer of free silaethene H 2 CSiH 2 ( 1 ) have been observed in the gas phase by millimeter wave spectroscopy. The search was guided by ab initio calculations at the MP 2 , CCSD, and CCSD(T) levels with TZ2Pf basis sets. The rotational constants determined experimentally and by ab initio methods for 1 with a planar C 2v ‐symmetric structure agree within about 0.5%. Compound 1 was best produced by vacuum pyrolysis of 5,6‐bis(trifluoromethyl)‐2‐silabicyclo[2.2.2]octa‐5,7‐diene in an Ar stream; 1 decomposes exponentially with a 1/ e lifetime at ambient temperature of 30±2 ms.