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A Crossed Beam and ab Initio Investigation on the Formation of Boronyldiacetylene (HCCCC11BO; X1Σ+) via the Reaction of the Boron Monoxide Radical (11BO; X2Σ+) with Diacetylene (C4H2; X1Σg+)
journal contribution
posted on 2013-08-29, 00:00 authored by Dorian
S. N. Parker, Nadia Balucani, Domenico Stranges, Ralf I. Kaiser, Alexander MebelThe reaction dynamics of the boron
monoxide radical (11BO; X2Σ+) with diacetylene
(C4H2; X1Σg+) were investigated at a nominal collision energy
of 17.5 kJ mol–1 employing the crossed molecular
beam technique and supported by ab initio and statistical
(RRKM) calculations. The reaction is governed by indirect (complex
forming) scattering dynamics with the boron monoxide radical adding
with its boron atom to the carbon–carbon triple bond of the
diacetylene molecule at one of the terminal carbon atoms without entrance
barrier. This leads to a doublet radical intermediate (C4H211BO), which undergoes unimolecular decomposition
through hydrogen atom emission from the C1 carbon atom via a tight
exit transition state located about 18 kJ mol–1 above
the separated products. This process forms the hitherto elusive boronyldiacetylene
molecule (HCCCC11BO; X1Σ+) in a bimolecular gas phase reaction under single collision
conditions. The overall reaction was determined to be exoergic by
62 kJ mol–1. The reaction dynamics are compared
to the isoelectronic diacetylene (C4H2; X1Σg+)–cyano
radical (CN; X2Σ+) system
studied previously in our group. The characteristics of boronyl-diacetylene
and the boronyldiacetylene molecule (HCCCC11BO; X1Σ+) as well as numerous intermediates
are reported for the first time.