Rate constants for H+(CH3)4−nSiHn, n=1–4

Rate constants for the reactions of H atoms with SiH4 and the methylsilanes, (CH3)4−nSiHn, n=1–4, have been measured at 298 K in pulsed photolysis experiments with H atoms produced by the mercury-sensitised photolysis of H2 and monitored by Lyman-α absorption. The values obtained, for n=1–4, respectively, are: k1 =(2.70±0.20)×10−13, k2=(3.94±0.29)×10−13, k3=(3.88±0.21)×10−13, and k4=(3.38±0.16)×10−13 cm3 s−1. These results show that methyl substitution enhances the reactivity of the Si–H bond towards H atom attack, and comparisons are made with the corresponding reactions of Cl, Br and O atoms.