Boron hydride

Boron Hydrides.—Ground-state wavefunctions of BH have been calculated using the GI and SOGI methods. Allowing ir-character in the orbitals produced a significant improvement in the description of the system. 

The use of average natural orbitals in configuration interaction calculations on the BH molecule has been discussed.  

MO calculations carried out on the BH3 system have been used to calculate harmonic force constants and vibrational frequencies for BH3.  

Some qualitative MO calculations on B2H6 and C2H6 indicate that dimerization of both BHg and CH3 should have zero or negligible activation energies. SCF calculations, using a basis of all j-type Gaussians, carried out to investigate the dimerization  

Upper limits for B- B nuclear-spin coupling constants have been obtained for a three-centre, two-electron B—— B bond in B2H3 ( 1.1 Hz) 

As is usually the case in the study of complicated reactions that involve a great many different species, more attention has been given to the analysis of reaction products and intermediates than to the problems of the investigation of the kinetics of possible elementary reaction steps. Analytical studies of the systems have been advanced by the development of techniques such as gas chromatography for the analysis of multicomponent systems and mass spectrometry for the detection of free radicals and other highly unstable species. Furthermore, since most 

However, in this structure 14 electrons are shown but the atoms have a total of only 12 valence electrons. It was also believed that borane, BH3, should be a stable compound because a structure for it could be drawn as 

However, Stock found after numerous attempts that it was impossible to isolate borane. We now see that compound as being electron deficient, and that characteristic usually leads to some sort of molecular aggregation. 

A molecular orbital diagram for a three-center B-H-B bond in diborane. In this diagram, f represents an atomic orbital and and represent the bonding and antibonding three-center wave functions, respectively. Note the relative energies of the atomic orbitals on boron and hydrogen atoms (ionization potentials 8.3 eV and 13.6 eV, respectively). 

The bonds are considered to arise from the combination of two boron orbitals that are hybrids of s and p orbitals with a b orbital on the hydrogen atom. Graphically, the formation of the three-center molecular orbital can be represented as shown here  

More complex boron hydrides, the polyhedral boranes, will be described in Section 8.3.5. 

A deltahedron is a polyhedron that possesses only triangular faces, e.g. an octahedron. 

At one time, there was considerable interest in the possibility of using boron hydrides as high-energy fuels, but in practice, it is difficult to ensure complete combustion to B2O3, and involatile pol5aners tend to block exhaust ducts. Although interest in fuel applications has faded. 

Higher yields of Na2[BgH6] are obtained by changing the in situ synthesis of Na[B3Hg] to reaction 12.79, followed by heating in diglyme at reflux for 36 hours. 

The name of a borane denotes the number of boron atoms, the number of hydrogen atoms, and the overall charge. The number of boron atoms is given by a Greek prefix (di-, tri-, tetra-, penta-, hexa- etc.), the exception being for nine and eleven, where the Latin nona- and undeca- are used. The number of hydrogen atoms is shown as an Arabic numeral in parentheses at the end of the name (see below). The charge for an ion is shown at the end of the name the nomenclature 

In counting the number of cluster-bonding electrons available in a borane, we first formally break down the cluster into fragments and determine the number of valence electrons that each fragment can contribute for cluster bonding. A procedure is as follows. 

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Other boron hydrides are known, most of them having the general formula B H + 4- for example pentaborane, B5H9, decaborane, BjqHi4. Each can be made by heating diborane in suitable conditions for example at 420 K, decaborane is obtained. Boron hydrides have been tried as rocket fuels. 

Hydroboration is a reaction m which a boron hydride a compound of the type R2BH adds to a carbon-carbon bond A carbon-hydrogen bond and a carbon-boron bond result... 

PORONCOMPOUNDS - BORON HYDRIDES, HETEROBORANES AND THEIRTffiTALLADERIVATIVES] (Vol 4) Bis(l,4,7-trithiacyclononane)gold(II) bis(tetraflouroborate) [125438-78-0]... 

Boron hydrides, heteroboranes, and their metalla derivatives... 

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