Boron atom reactions with the halomethanes

Rate constants have been measured for the reactions of boron atoms with a series of halomethanes. The experiments were performed in a linear flow tube apparatus at 300 K. The measured rate constants in units of cm3 molecule−1 s−1 are CCl4:9.5×10−11; CCl3H:4.8×10−11; CCl2H2:6.2×10−11; CClH3:1.4×10−11; CCl3F:3.1×10−11; CCl2F2:5.5×10−12; CClF3:1.7×10−13; CF4:<3×10−14; CF3H:<2×10−14. The reaction of boron with all the chloromethanes is facile. The chlorofluoromethanes present a more complex pattern. Noteworthy is the low reactivity of the channel to produce BF, furthermore, the presence of fluorine in the halomethanes reduces the reactivity at the chlorine site. Semiempirical MNDO calculations were performed on the reacting systems. These calculations suggest possible explanations for the observed results.