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A borane is a compound with the formula BR x H y although examples include multi-boron derivatives. A large family of boron hydride clusters is also known. In addition to some applications in organic chemistry , the boranes have attracted much attention as they exhibit structures and bonding that differs strongly from the patterns seen in ...
Ball-and-stick models showing the structures of the boron skeletons of borane clusters. The following polyhedra are closo polyhedra, and are the basis for the 4n rules; each of these have triangular faces. [10] The number of vertices in the cluster determines what polyhedron the structure is based on.
The parent member BH 3 is called borane, but it is known only in the gaseous state, and dimerises to form diborane, B 2 H 6. The larger boranes all consist of boron clusters that are polyhedral, some of which exist as isomers. For example, isomers of B 20 H 26 are based on the fusion of two 10-atom clusters.
Boron hydride clusters are compounds with the formula B x H y or related anions, where x ≥ 3. Many such cluster compounds are known. Common examples are those with 5, 10, and 12 boron atoms. Although they have few practical applications, the borane hydride clusters exhibit structures and bonding that differs strongly from the patterns seen in ...
Borane makes a strong adduct with triethylamine; using this adduct requires harsher conditions in hydroboration. This can be advantageous for cases such as hydroborating trienes to avoid polymerization. More sterically hindered tertiary and silyl amines can deliver borane to alkenes at room temperature. Borane(5) is the dihydrogen complex of
Pyrolysis of diborane gives hydrogen and diverse boron hydride clusters. For example, pentaborane was first prepared by pyrolysis of diborane at about 200 °C. [18] [19] Although this pyrolysis route is rarely employed, it ushered in a large research theme of borane cluster chemistry.
In chemistry, the Jemmis mno rules represent a unified rule for predicting and systematizing structures of compounds, usually clusters.The rules involve electron counting. They were formulated by E. D. Jemmis to explain the structures of condensed polyhedral boranes such as B 20 H 16, which are obtained by condensing polyhedral boranes by sharing a triangular face, an edge, a single vertex, or ...
In hydroboration, alkenes insert into borane B-H bonds, with anti-Markovnikov stereochemistry. Hydroboration occurs stereospecifically syn — on the same alkene face. The transition state for this concerted reaction can be visualized as a square with the corners occupied by carbon, carbon, hydrogen and boron, maximizing overlap between the ...