18433-84-6Relevant articles and documents
Gibb, Terence C.,Greenwood, Norman N.,Spalding, Trevor R.,Taylorson, Derek
, (1979)
Gibb, Terence C.,Greenwood, Norman N.,Spalding, Trevor R.,Taylorson, Derek
, (1979)
Kinetic studies of reactions of hexaborane(10) with other binary boranes in the gas phase
Attwood, Martin D.,Greatrex, Robert,Greenwood, Norman N.,Potter, Christopher D.
, p. 144 - 152 (2007/10/03)
Cothermolysis reactions of B6H10 with the binary boranes B2H6, B4H10, B5H9, and B5H11 have been studied by a quantitative mass-spectrometric technique to gain insight into the role of B6H10 in borane interconversion reactions. Except in the B6H10-B5H9 system the initial rate of consumption of B6H10 was found to be considerably more rapid than in the thermolysis of B6H10 alone, indicating that interactions were occuring. Detailed kinetic studies of the B6H10-B2H6 and B6H10-B4H10 reactions showed that the rate of consumption of B6H10 was governed in each case by the rate-determining step in the decomposition of the co-reactant, the orders being 3/2 with respect to B2H6 and 1 with respect to B4H10; a considerable increase in the conversion of B6H10 to B10H14 at the expense of polymeric solids was also observed. Added hydrogen was found to have very little effect on the reaction rates and product distributions in the cothermolysis reactions, in marked contrast to its effect on the reactions of B2H6 and B4H10 alone. The kinetic results are entirely consistent with earlier suggestion, based on qualitative observations, that the reactive intermediates {B3H7} and {B4H8} are scavenged by reactions with B6H10, and suggest strongly that this borane, unlike B6H12, plays a pivotal role in the build-up to B10H14 and other higher boranes.
Influence of Added Hydrogen on the Kinetics and Mechanism of Thermal Decomposition of Tetraborane(10) and of Pentaborane(11) in the Gas Phase
Attwood, Martin D.,Greatrex, Robert,Greenwood, Norman N.
, p. 391 - 398 (2007/10/02)
The effects of added hydrogen on the kinetics of the first-order thermal decomposition of the two arachno species tetraborane(10) and pentaborane(11) have been studied in detail by a mass-spectrometric method.In the case of B4H10, the order and activation energy were unaltered, but the reaction rate was retarded and there was a marked change in product distribution: the percentage yield of B5H11 remained the same, but B2H6 was formed in preference to B5H9, B6H12, B10H14, and involatile solids.These results provide cogent new evidence that B4H10 decomposes via the single rate-determining step (i), but raise doubts about the validity of subsequent steps in the B4H10+H2 (i) previously proposed mechanism.In the thermolysis of B5H11 there was a dramatic change in product distribution, but the order, activation energy, and initial rate of disappearance of B5H11 were all unaffected by the presence of the added H2.These results establish for the first time that the so-called 'equilibrium' (ii) proceeds in the forward direction via the rate-determining B5H11+H2B4H10+1/2B2H6 (ii) dissociation (iii), followed by the rapid reactions (-i) and (iv).They also imply that in the thermolysis B5H11->+ (iii) 2->B2H6 (iv) of B5H11 in the absence of added H2 the reactive intermediate reacts subsequently with itself and is not consumed by reaction with B5H11.
