KINETICS OF THE GAS-PHASE REACTION BETWEEN IODINE AND TRIMETHYLGERMANE AND THE BOND-DISSOCIATION ENERGY D(ME3GE-H)

The title reaction has been investigated in the temperature range 420-474 K. The only products, formed in equal quantities, were trimethylgermyl iodide and hydrogen iodide. Despite some surface sensitivity, the reaction was found to obey the nonsurface-dependent rate law -d[I2]/dt = k[I2]1/2[Me3GeH]/(1 + k′[HI]/[I2]) provided that the ratio [Me3GeH]0/[I2]0 was sufficiently large. This expression is consistent with an iodine atom abstraction mechanism and for the step I· + Me3GeH → Me3Ge· + HI (1), log (k1/dm3 mol-1 s-1) = (9.94 ± 0.10) - (45.3 ± 0.9 kJ mol-1)/RT ln 10, has been obtained. From this the bond dissociation energy D(Me3Ge-H) = 340 ± 10 kJ mol-1 (81 kcal mol-1) is deduced. This value is compared with other estimates. © 1979 American Chemical Society.