Properties of Tetrahydroborates

The preparation and various aspects of the properties of tetrahydroborates have been comprehensively reviewed.2 7,914 87,88 Therefore, only substituted derivatives of the tetrahydroborates will be dealt with in this section. The methods of synthesis of these compounds are summarized in Table 8. 

The IR and NMR data were consistent with the bidentate bridging mode of the HBBN ligand as confirmed by X-ray analysis. The pseudotetrahedral arrangement of the ligands around U is characterized by the average Cg-U-Cg angle of 115(1)". The U-C(cp)av is 2.76(1) A, and the U-B distance 2.78(3) A is typical for a bidentate bridge (the H were not located). The complex exhibits the characteristic properties of tetrahydroborate uranium complexes as molecularity, volatility, thermal stability and resistance to Lewis bases. 

Cesium superoxide, 5 700 Cesium tetrachlorogold, 5 701 Cesium tetrahydroborate, physical properties of, 4 194t Cesium trifluoroacetate, 5 701 Cesium vapor thermionic convertor, 5 704-705 Cesspools, 25 915... 

Lithium tetrahydridothallate(III), 24 632 Lithium tetrahydroborate, physical properties of, 4 194t Lithium—thionyl chloride cells, 3 466 characteristics, 3 462t speciality for military and medical use, 3 430t... 

Potassium superoxide, 18 416-417 20 606 Potassium tetrafluoroaluminate, 2 360-361, 370-372, 378-379 Potassium tetrafluoroborate, 4 144t Potassium tetrahydroborate, physical properties of, 4 194t... 

Rubidium hydroxide, 27 821-822 Rubidium iodide, 27 823 Rubidium metal alloys, 27 816 Rubidium metal, pure, 27 818 Rubidium oxides, 27 816, 823 Rubidium ozonide, 78 417 Rubidium silicates, 22 452 Rubidium sulfate, 27 821 Rubidium superoxide, 78 417 Rubidium tetrahydroborate physical properties of, 4 194t Ruby, 2 405 color, 7 329 Ruby glass, 7 344... 

Sodium tetrahydroborate, 4 193-197 economic aspects, 4 228 physical properties of, 4 194t Sodium tetrasulfide, 22 874-875 chemical analysis of, 22 875 health and safety factors related to, 22 875... 

This group of highly reactive compounds includes several which have found extensive use in preparative chemistry [1], Properties and reactions of several covalent tetrahydroborates have been reviewed [2], Preparation and properties of several new hydrides are given which are of interest as high-energy fuels in propellant systems [3,4], Individually indexed compounds are ... 

The physical and chemical properties of the tetrahydroborates show more contrasts than the salts of nearly any other anion. The alkali metal salts are the most stable. In dry air, NaBH4 is stable at 300°C and in vacuo to 400°C with only partial decomposition. In contrast, several tetrahydroborates, including the titanium, thallium, gallium, copper, and silver salts, are unstable at or slightly above ambient temperatures. The chemical and physical properties of the tetrahydroborates are closely related to molecular structure. Sodium tetrahydroborate, which is typical of the alkali metal tetrahydroborates except for the lithium salt, has a face-centered cubic (fee) crystal lattice which is essentially ionic and contains the tetrahedral [BHJ- anion. The tetrahydroborates of the polyvalent metals are in many cases the most volatile derivatives of these metals known. Aluminum tris(tetrahydroborate)... 

Chlopek K, Frommen C, Leon A, Zabara O and Fichtner M (2007), Synthesis and properties of magnesium tetrahydroborate, Mg(BH4)2, J. Mater. Chem., 17, 3496-3503. 

The physical properties of the tetrahydroborates and the tetrahydroalanates are to a large extent still not known. 

S.2 Physical Properties of Compounds Containing the Tetrahydroborate Group... 

The synthesis, stability, and properties of phenylaluminium tetrahydroborates have been studied, PhgAl dissolves readily in Al(BH4)s to give the solid dimeric compound PhaAKBH ). ... 

Mixed hydrido-alkyl complexes of gallium have been prepared, e.g. reactions (20)—(24), (M = Na or K R = Me or Et). The synthesis and properties of dimethylgallium tetrahydroborate have been examined, ... 

Tetrahydroborates. The tetrahydroboranes constitute the most commercially important group of boron hydride compounds. Tetrahydroborates of most of the metals have been characterized and their preparations have been reviewed (46). The important commercial tetrahydroborates are those of the alkah metals. Some properties are given ia Table 4. 

Despite the fact that many boron hydride compounds possess unique chemical and physical properties, very few of these compounds have yet undergone significant commercial exploitation. This is largely owing to the extremely high cost of most boron hydride materials, which has discouraged development of all but the most exotic appHcations. Nevertheless, considerable commercial potential is foreseen for boron hydride materials if and when economical and rehable sources become available. Only the simplest of boron hydride compounds, most notably sodium tetrahydroborate, NajBHJ, diborane(6), B2H, and some of the borane adducts, eg, amine boranes, are now produced in significant commercial quantities. 

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