18433-84-6Relevant academic research and scientific papers
Chemical and phase transformations in the systems hydrogen-sorbing intermetallic compound-diborane
Kravchenko,Kalinnikov,Shilkin
, p. 865 - 867 (2007/10/03)
The reactions of the intermetallic compounds CeFe2, CeCo 2, and λ3-ScFe2 with B2H 6 at 4.8 × 103 Pa, 293-573 K, and various contact times were studied. CeFe2 decompose
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.
KINETICS AND MECHANISM OF THE THERMOLYSIS AND PHOTOLYSIS OF BINARY BORANES.
Greenwood,Greatrex
, p. 857 - 868 (2008/10/08)
The mechanisms by which gaseous boron hydrides so readily interconvert and build up into larger clusters has excited considerable academic and industrial interest for several decades. This paper describes recent progress that has been made in unravelling this complex series of interconversion reactions. Initial reaction rates have been studied mass spectrometrically to obtain rate equations, orders of reaction and energies of activation. Detailed and continuous product analysis for H//2 and all the volatile boranes formed, coupled with a study of cothermolysis reactions of selected pairs of boranes gives further insight into the processes occurring. Crucial aspects of the thermolysis of B//2H// 6, B//4H//1//0, B//5H//1//1, and B//6H//1//0 are discussed, as are the effects of the added H//2 and the cothermolysis of B//6H//1//0 with alkenes. The final section presents data on the UV absorption spectra and photolytic stability of eight volatile boranes and the reaction kinetics of B//6H//1//0 photolysis.
New, systematic syntheses of boron hydrides via hydride ion abstraction reactions: Preparation of B2H6, B4H10, B5H11, and B10H14
Toft, Mark A.,Leach,Himpsl, Francis L.,Shore, Sheldon G.
, p. 1952 - 1957 (2008/10/08)
The boron hydrides B2H6, B4H10, B5H11, and B10H14 are prepared in good yields through hydride ion abstraction reactions when the borane anions BH4-, B3H8-, B4H9-, and B9H14- respectively are treated with 1 molar equiv of a Lewis acid BX3 (X = F, Cl, or Br), generally in the absence of a solvent, for reaction periods of 1-4 h. A high-yield (85-90%) method for the conversion of B5H9 to B9H14- is presented as the precursor to the practical conversion of B5H9 to B10H14 (45-50%). Additionally, treatment of the anion BrB3H7- with BBr3 results in the formation of 2-BrB4H9 in low yield (15%). The hydride ion abstraction reactions by BBr3 and BCl3 lead to the new anions HBBr3- and HBCl3-.
