Triborane

Triborane B3H7 can be readily generated from B3H8 by reaction with a nonoxidizing protic acid in the presence of an ether. Under these conditions it must be stabilized as a Lewis acid base adduct. The 1 1 THF adduct of B3H7 is quite stable and is most often used for further reactions. The ether may be readily replaced by stronger bases such as dimethylamine [22] ... 

Fig. 2.1-12. Structural representations of triborane B3H7 and its thiocyanate anion. (A) Calculated ground state structure of B3H7 (B) ambient temperature structure of the B3H7NCS anion (C) low temperature structure of the B3H7NCS anion.

While the THF adduct of triborane(7) reacts with Bu -B=N-Bul by hydrobora-tion to produce a /<-aminodiborane (see Section 2.1.4.1) the analogous reaction... 

C. The Preparation and Chemistry of the Dimethyl Ether Adduct of Triborane(7)j Diborane(4) Adducts... 

The dimethyl ether adduct of triborane(7) 124> has been prepared by the cleavage of tetraborane(lO) at room temperature according to the equation ... 

Triphenyl Telluronium Triboranate-82 1.00 g (2.3 mmol) of triphenyl telluronium bromide are dissolved in 100 ml of water and 0.26 g (2.2 mmol) of tetramethyl ammonium triboranate-8 are dissolved in 50 ml of water. The two solutions are cooled to 0 and mixed. The precipitate is filtered off, washed under nitrogen with diethyl ether, and dried in a stream of nitrogen yield 0.83 g (95%) m.p. 57° (dec ). 

The reaction of diborane(6) with bis or tris(dimethylamino)borane has recently been shown to be synthetically useful in the stepwise buildup of a boron-nitrogen chain leading to bis( -dimethylamino)triborane(9).7... 

To a certain degree the presented catalytic results can be expected to be applicable to AB-related compounds. Yoon and Sneddon have demonstrated that the hydrolysis of ammonia triborane NH3B3H7 can be performed vith concentrations up to 22.7 wt.% [121] using a 5 wt.% Rh catalyst at 21 °C, achieving a hydrogen release of 6.1 wt.% solution based. 

The structure of triborane triamine (borazole), BaNgH appears to be analogous with benzene . The analogy, however, is not complete since in triborane triamine the greatest contribution to the molecular resonance will be given by the single bond structure... 

As illustrated in Fig. 7-52, in the related l-[l,l -bis(diphenylphosphino)ferrocene]-palladatetraborane complex, the palladium atom still possesses a pseudo-square-planar environment, two bonds being formed with the phosphorus atoms and the two remaining bonds with the triborane ligand. The cyclopentadienyl rings of the sandwich fragment are parallel and nearly staggered [156]. 

Two more efficient methods for the synthesis of bis(/x-dimethylamino)-triborane(9) (38) have been described, uiz. the reaction of Me2NHBH2-NMe2BH3 + K (in ether solvents), to give KMe2NBH2NMe2BH3 treatment of this with excess B2H6 forms the desired compound.287 Alternatively, HB(NMe2)2 + B2H6 forms this species directly. Detailed B n.m.r. spectroscopic studies have been made of the compound and of the courses of a number of its reactions. 

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