Pyrophoric compounds, boranes

While the connection between the structure of the hydrides and their pyrophoric behavior seems to be obscure, it should be pointed out that the compounds of hydrogen fall into three distinctive groups the above-described phosphines, silanes, and boranes, which have covalent bonds the salt-like hydrides of the alkali and alkaline earth metals and the interstitial, nonstoicbiometric or berthollide —type hydrides of the transition metals—e.g. the rare earths, titanium, and zirconium. Pyrophoric compounds are found in all three groups. 

ALKYLALUMINIUM DERIVATIVES, ALKYLBORANES, ALKYLHALOBORANES ALKYLHALOPHOSPHINES, ALKYLHALOSILANES, ALKYLMETALS ALKYLNON-METAL HYDRIDES, ALKYLPHOSPHINES, ALKYLSILANES ARYLMETALS, BORANES, CARBONYLMETALS, COMPLEX ACETYLIDES COMPLEX HYDRIDES, HALOACETYLENE DERIVATIVES HEXAMETHYLNITRATODIALUMINATE SALTS, METAL HYDRIDES NON-METAL HYDRIDES, ORGANOMETALLICS, PYROPHORIC ALLOYS PYROPHORIC CATALYSTS, PYROPHORIC IRON-SULFUR COMPOUNDS PYROPHORIC METALS... 

Pyrazaboles substituted on either the ring or the boron may be obtained by reaction between the appropriately substituted pyrazole and the appropriately substituted borane.11 For example the 2,6-dibromo-4,4,8,8-tetraethylpyrazabole can be made by the reaction between 4-bromopyrazole and pyrophoric triethylborane in xylene at reflux temperature. Another route to such compounds involves the dihydrobis(l-pyrazolyl)borate... 

Lithium aminoborohydrides. The reagent 1 is a typical member of a number of lithium aminoborohydrides, prepared by reaction of BuLi with amine boranes in quantitative yields. These reagents can be stored at 25 under N2 for at least six months they are not pyrophoric. They are comparable to LiAlFL as reductants. Thus 1 reduces carbonyl compounds (including esters) in high yield. Lactones and anhydrides are reduced, but carboxylic acids are not reduced. In addition 1 reduces amides, epoxides, oximes, nitriles, and even halides. 

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