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Reaction of diborane with ammonia mainly gives the diammoniate salt [H 2 B(NH 3) 2] + [BH 4] − (diammoniodihydroboronium tetrahydroborate). Ammonia borane is the main product when an adduct of borane is employed in place of diborane: [5] BH 3 + NH 3 → BH 3 NH 3 + THF. It can also be synthesized from sodium borohydride.
The ammonia-borane adduct (H 3 N → BH 3) is given as a classic example: the bond is weak, with a dissociation energy of 31 kcal/mol (cf. 90 kcal/mol for ethane), and long, at 166 pm (cf. 153 pm for ethane), and the molecule possesses a dipole moment of 5.2 D that implies a transfer of only 0.2 e – from nitrogen to boron.
Molecular structure of ammonia and its three-dimensional shape. It has a net dipole moment of 1.484 D. Dot and cross structure of ammonia. The ammonia molecule has a trigonal pyramidal shape, as predicted by the valence shell electron pair repulsion theory (VSEPR theory) with an experimentally determined bond angle of 106.7°. [36]
Note that the dipole moments drawn in this diagram represent the shift of the valence electrons as the origin of the charge, which is opposite the direction of the actual electric dipole moment. The bond dipole moment [5] uses the idea of electric dipole moment to measure the polarity of a chemical bond within a molecule. It occurs whenever ...
It is moderately polar with a dipole moment of 0.6 D. The nitrogen center is basic but much less so than ammonia. It is hydrolyzed by hot water to release ammonia and hypochlorous acid. NCl 3 + 3 H 2 O → NH 3 + 3 HOCl. Concentrated samples of NCl 3 can explode to give N 2 and chlorine gas. [citation needed] 2 NCl 3 → N 2 + 3 Cl 2
It is prepared in modern times both by direct reaction of ammonia and fluorine and by a variation of Ruff's method. [6] It is supplied in pressurized cylinders. NF 3 is slightly soluble in water without undergoing chemical reaction. It is nonbasic with a low dipole moment of 0.2340 D.
The electric dipole moment is a measure of the separation of positive and negative electrical charges within a system: that is, a measure of the system's overall polarity. The SI unit for electric dipole moment is the coulomb-metre (C⋅m). The debye (D) is another unit of measurement used in atomic physics and chemistry.
The compound was reported in 1926 by the chemists Alfred Stock and Erich Pohland by a reaction of diborane with ammonia. [3] Borazine can be synthesized by treating diborane and ammonia in a 1:2 ratio at 250–300 °C with a conversion of 50%. 3 B 2 H 6 + 6 NH 3 → 2 B 3 H 6 N 3 + 12 H 2