Reactions of Laser-Ablated Boron Atoms with Methyl Halides in Excess Argon. Infrared Spectra and Density Functional Theory Calculations on CH3BX, CH2BX, and CHBX (X = F,Cl,Br)

Abstract

Laser-ablated boron atoms react with methyl fluoride in an argon stream to form two major products: CH2BF and CHBF. In similar reactions of boron with methyl chloride and methyl bromide, both CH2BX and CHBX are also observed, as well as the primary insertion products, CH3BCl and CH3BBr, respectively. Infrared spectra of isotopic combinations of B and CH3X and density functional theory frequency calculations provide evidence for the product identification. Both products form via insertion into the C−X bond followed by loss of one or two H atoms for all reactions. Comparisons are made with the products of the reactions of B with C2H6, CH3NH2, and CH3OH, all of which are isoelectronic with CH3F. The calculations not only predict the vibrational frequencies exceptionally well, but also predict that there is no dative bonding in either CH2BX or CHBX, despite the empty p-orbital on B and the filled p-orbitals on the halogen atom.