Propargylene: A C3H2 isomer with unusual bonding
- 15 October 1989
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 91 (8) , 4763-4773
- https://doi.org/10.1063/1.456765
Abstract
Propargylene was identified in a matrix as a product of photolysis of cyclopropenylidene and diazopropyne. The molecule is a triplet. The optimum geometry predicted by ab initio calculations corresponds to a structure HC≡C–C̈H. The transition structure in the interconversion HC≡C–C̈H⇄HĊ=C=ĊH⇄HC̈–C≡CH is very low in energy and close to the energy of the vibrational ground state. Owing to this nonrigidity, computed infrared (IR) frequencies based on a harmonic treatment do not match the experimental spectrum. When this nonrigidity is taken into account by using a nonharmonic approximation calculated UMP2/6‐31G** IR spectra are in good agreement with the observed spectra of HCCCH and DCCCD.Keywords
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