A crossed beam and ab initio investigation on the formation of vinyl boron monoxide (C2H3BO; X1A′) via reaction of boron monoxide (11BO; X2Σ+) with ethylene (C2H4; X1Ag)

Abstract

The reaction dynamics of the boron monoxide radical (¹¹BO; X²Σ⁺) with ethylene (C₂H₄; X¹A_g) were investigated at a nominal collision energy of 12.2 kJ mol⁻¹ employing the crossed molecular beam technique and supported by ab initio and statistical (RRKM) calculations. The reaction is governed by indirect scattering dynamics with the boron monoxide radical attacking the carbon–carbon double bond of the ethylene molecule without entrance barrier with the boron atom. This addition leads to a doublet radical intermediate (O¹¹BH₂CCH₂), which either undergoes unimolecular decomposition through hydrogen atom emission from the C1 atom via a tight transition state located about 13 kJ mol⁻¹ above the separated products or isomerizes via a hydrogen shift to the O¹¹BHCCH₃ radical, which also can lose a hydrogen atom from the C1 atom. Both processes lead eventually to the formation of the vinyl boron monoxide molecule (C₂H₃BO; X¹A′). The overall reaction was determined to be exoergic by about 40 kJ mol⁻¹. The reaction dynamics are also compared to the isoelectronic ethylene (C₂H₄; X¹A_g) – cyano radical (CN; X²Σ⁺) system studied earlier.