Hydride



Hydride is the name given to the bonding:

  • Saline hydrides, which have significant ionic character,
  • Covalent hydrides, which include the hydrocarbons and many other compounds, and
  • Interstitial hydrides, which may be described as having metallic bonding.

Hydride ion

See also: hydrogen anion.

Aside from electron affinity, 72.77 kJ/mol, thus hydride is so basic that it is unknown in solution. The reactivity of the hypothetic hydride ion is dominated by its exothermic protonation to give dihydrogen:

H− + H+ → H2; ΔH = −1675 kJ/mol

As a result, the hydride ion is one of the strongest reducing agent:

H2 + 2e− ⇌ 2H−; Eo = −2.25 V

Ionic hydrides

In ionic hydrides the hydrogen behaves as a organic synthesis:

KH → C6H5C(O)CH2K + H2

Such reactions are heterogeneous, the KH does not dissolve. Typical solvents for such reactions are hydroxide. Hydrogen gas is liberated in a typical acid-base reaction.

NaH + H2ΔG = −109.0 kJ/mol

Alkali metal hydrides react with metal halides. aluminium chloride.

4 LiH + AlCl3 → LiAlH4 + 3 LiCl

Covalent hydrides

In covalent hydrides, hydrogen is sodium borohydride (NaBH4) and lithium aluminium hydride and hindred reagents such as DIBAL.

Transition metal hydrido complexes

Most transition homoleptic metal hydride.

Interstitial hydrides of the transitional metals

Structurally related to the saline hydrides, the transition metals form binary hydrides which are often non-stoichiometric, with variable amounts of hydrogen atoms in the lattice, where they can migrate through it. In fuel cells. Hydrogen gas is liberated proportional to the applied temperature and pressure but not to the chemical composition.

Interstitial hydrides show certain promise as a way for safe hydrogen storage. During last 25 years many interstitial hydrides were developed that readily absorb and discharge hydrogen at room temperature and atmospheric pressure. They are usually based on intermetallic compounds and solid-solution alloys. However, their application is still limited, as they are capable of storing only about 2 weight percent of hydrogen, which is not enough for automotive applications.

Nomenclature

Various metal hydrides are currently being studied for use as a means of hydrogen storage in reducing agents, and many promising uses in hydrogen economy. The following is a list of main group hydride nomenclature:

According to the convention above, the following are "hydrogen compounds" and not "hydrides":

Examples:

Isotopes of hydride

Protide, deuteride, and tritide are used to describe ions or compounds, which contain enriched tritium, respectively.

Precedence convention

According to ammonia), versus H2O, 'hydrogen oxide' (water).

See also
 
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