Carbon boron hydrides

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... 

Examination of this anomaly revealed that the carbon-carbon double bond was also reacting, producing a carbon-boron bond with loss of an equivalent of hydride. 

Interstitial Solid Solutions Interstitial solid solutions involve occupation of a site by introduced ions or atoms, which is normally empty in the crystal structure, and no ions or atoms are left out. Many metals form interstitial solid solutions in which small atoms (e.g., hydrogen, carbon, boron, nitrogen) enter empty interstitial sites within the host structure of the metal. Palladium metal is well known for its ability to absorb an enormous volume of hydrogen gas, and the product hydride is an interstitial sohd solution of formula PdH, 0 0.7, in which hydrogen atoms occupy... 

This chapter concerns carboranes (carbaboranes), which are boron clusters with at least one carbon atom as part of the polyhedral cage. Published studies on carboranes before 1981 were reviewed in GOMC (1982) and between 1982 and 1992 in COMC (1995). The present review covers the period of 1992 to early 2005. Unlike in previous chapters, boron hydrides with organic substituents attached to a boron atom, organopolyboron hydrides, are not discussed in this chapter. Borane clusters containing at least one non-carbon atom as part of the cage framework are reviewed in Chapters 3.03, 3.04 and 3.05 of this volume. 

Wade electron counting rules borane-like cluster nomenclature. On initially studying compounds such as boranes (boron hydrides) and carboranes (or carbaboranes boron—carbon hydrides), Wade (1976) proposed a number of rules which have then been extended to several compounds and which relate the number of skeletal electrons with the structure of deltahedral clusters. A polyhedron which has only A-shaped, that is triangular, faces is also called a deltahedron. 

Boron hydrides are soluble in carbon disulfide, diglyme and ethyl acetate. They react with water. 

Ach on carbon orbital hybridization in hydrocarbons is not found to hold quantitatively for the boron hydrides. 

Borides Carbon boride, CB6. and silicon borides SiB3 and SiB6 are hard, crystalline solids, produced in ihe electric furnace magnesium boride, Mgi B2, brown solid, by reaction of boron oxide and magnesium powder ignited, forms boron hydrides with HC1 calcium boride, Ca3 B2, forms boron hydrides and hydrogen gas with IIC1. 

CARBORANE. A cry stalline compound composed of boron, carbon, and hydrogen. It can be synthesized in various ways, chiefly by the reaction of a borane (penta-or deca-) with acetylene, either at high temperature in the gas phase or in the presence of a Lewis base. Alkylated derivatives have been prepared. Carborancs have different structural and chemical characteristics and should not be conTused with hydrocarbon derivatives or boron hydrides. The predominant structures arc the cage type, the nest type, and the web type, these terms being descriptive of the arrangement of atoms in the crystals. Active research on cargorane chemistry has been conducted under sponsorship of the U.S. Office of Naval Research, http //www.onr.navy.mil/... 

But carbon is not unique in forming bonds to itself because other elements such as boron, silicon, and phosphorus form strong bonds in the elementary state. The uniqueness of carbon stems more from the fact that it forms strong carbon-carbon bonds that also are strong when in combination with other elements. For example, the combination of hydrogen with carbon affords a remarkable variety of carbon hydrides, or hydrocarbons as they usually are called. In contrast, none of the other second-row elements except boron gives a very extensive system of stable hydrides, and most of the boron hydrides are much more reactive than hydrocarbons, especially to water and air. 

Decaborane (and possibly some other boron hydrides) in the presence of carbon tetrachloride, and possibly other halogenated hydrocarbons, forms a very shock-sensitive high explosive. 

This article covers only a part of the chemistry of boron. Boron-carbon compounds are covered in other articles in this volume see Boron Organoboranes Boron Metallacarbaboranes, and Boron Polyhedral Carboranes). The main subject of the latter two articles, and the separate one on Boron Hydrides is the extensive chemistry of the multicenter bonded boron-hydride systems. This area has been a major focus of boron research for the past 60 years. There is some direct overlap between the two articles Borides Solid-state Chemistry and Borates Solid-state Chemistry, and this more general one covering the inorganic chemistry of boron. Boron-Nitrogen Compounds are also covered separately. These articles should be consulted for more detailed discussions of the structure, bonding, and properties of borides, solid-state borates, and boron-nitrogen compounds. 

Metallacarbaborane (also called metallacarborane) an electron-deficient compound, usually a polyhedral cluster comprising an array of boron-hydride (BH), carbon-hydride (CH), and metal (ML, where L = ligand) fragments the inclusion of a substituted carbon fragment CR (R = alkyl, aryl, or trimethylsilyl) in place of a CH unit is common... 

---