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6855489 
Journal Article 
Synthesis and chemical transformations of ionic octahydrotriborates: Cleavage of the B3H8- anion 
Titov, LV; Titov, LV 
2003 
1 
Russian Journal of Inorganic Chemistry
ISSN: 0036-0236
EISSN: 1531-8613 
48 
10 
1471-1479 
English 
WOS:000186170300005 
New octahydrotriborates LiB3H8 . 4Dn (Dn is dioxane), LiB3H8 . 2Dn, NaB3H8 . Dn, KB3H8 . 2.5Dn, [Mg(NH3)(6)](B3H8)(2), [Mg(Dg)(2)](B3H8)(2) (Dg is diolyme), [Mg(Dg)(2)](BH4)(B3H8), [Ca(Dg)(2)](BH4)(B3H8), [Sr(Dg)(2)](B3H8)(2), and [C(NH2)(3)]B3H8 were synthesized, and solvated salts with the B3H8- anion were prepared. It was shown that LiB3H8 forms hydrazinates of variable composition containing one to four hydrazine moles and the ammoniates LiB3H8 . 4NH(3) and LiB3H8 . 3NH(3). The properties of the resulting salts and their solvate's were studied. The temperature limits of the partial or complete desolvation of the solvates were established. The solubility of NaB3H8 . 3Dn and tetraalkylammonium octahydrotriborates in organic solvents was studied over a wide temperature range. The heats of combustion in an oxygen atmosphere were measured, and the enthalpies of formation were calculated: Delta(f)H(0)(Me4NB3H8) = -157.4 kJ/mol, Delta(f)H(0)(Et4NB3H8) = -262.5 kJ/mol, and Delta(f)H(0)(Bu4NB3H8) = -443.8 kJ/mol. The destruction of the B3H8- anion to give the BH4- ion and unstable borane B2H4 was found and confirmed experimentally for the first time. The destruction was studied in reactions of octahydrotriborates with Lewis bases (hydrazine and triphenylphosphine) and Lewis acids (AlCl3 and Al(BH4)(3)) and also in heat treatment. The B2H4 borane was isolated as the B2H4 . 2PPh(3) adduct. The reaction NaB3H8 . Dn --> NaBH4 + B5H9 + (H-2 + Dn) can be conveniently used to prepare pentaborane(9) under laboratory conditions. The reaction of octahydrotriborate with aluminum chloride Bu4NB3H8 + AlCl3 --> Bu4N[Cl3Al(BH4)] + B4H10 allows one to prepare tetraborane(10) with a fairly high yield and with a satisfactory degree of purity.<