- A Kinetic Study of the Gas-phase Thermolysis of Pentaborane(11)
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The kinetics of thermal decomposition of pentaborane(11) have been investigated by a mass-spectrometric technique in the pressure range 1.75-10.50 mmHg and temperature range 40-150 deg C.In conditioned Pyrex vessels the reaction was shown to occur by a homogeneous gas-phase process according to the first-order initial-rate low -d/dt=1.3*107 exp(-72600/RT).The main volatile products are H2 and B2H6, the latter appearing at the rate of ca. 0.5 mol per mol of B5H11 consumed.Pentaborane (9) is also produced, at less than half the rate of B2H6, together with even smaller amounts of hexaboranes and B10H14, and traces of B4H10; some 40-45percent of the boron is converted into involatile solid hydride BHx, where x varies from ca. 2.0 at 40 deg C to ca. 1.1 at 150 deg C.No obvious dependence on temperature was detected in the overall distribution of boron between volatiles and solid, but the production of B5H9 was favoured at higher temperatures.Mechanistic implications of these results are discussed.
- Attwood, Martin D.,Greatrex, Robert,Greenwood, Norman N.
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