Aluminium hydride

Aluminium hydride
Names

Preferred IUPAC name Aluminium hydride
Systematic IUPAC name Alumane
Other names Alane Aluminic hydride Aluminium(III) hydride Aluminium trihydride Trihydridoaluminium
Identifiers
CAS Number	7784-21-6^Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:30136^Y
ChemSpider	13833^Y 17625618 (³H₃)^Y
ECHA InfoCard	100.029.139
Gmelin Reference	245
PubChem	14488 14399066 (²H₃) 16721258 (³H₃)
InChI InChI=1S/Al.3H^Y Key: AZDRQVAHHNSJOQ-UHFFFAOYSA-N^Y InChI=1S/Al.3H Key: AZDRQVAHHNSJOQ-UHFFFAOYSA-N InChI=1/Al.3H/rAlH3/h1H3 Key: AZDRQVAHHNSJOQ-FSBNLZEDAV
SMILES [AlH3]
Properties
Chemical formula	AlH₃
Molar mass	29.99 g/mol
Appearance	white crystalline solid, non-volatile, highly polymerized, needle-like crystals
Density	1.477 g/cm³, solid
Melting point	150 °C (302 °F; 423 K) starts decomposing at 105 °C (221 °F)
Solubility in water	reacts
Solubility	soluble in ether reacts in ethanol
Thermochemistry
Specific heat capacity (C)	40.2 J/mol K
Std molar entropy (S^o₂₉₈)	30 K/mol K
Std enthalpy of formation (Δ_fH^o₂₉₈)	-11.4 kJ/mol
Gibbs free energy (Δ_fG˚)	46.4 kJ/mol
Related compounds
Related compounds	Lithium aluminium hydride, diborane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y (what is ^YN ?)
Infobox references

Aluminic hydride
Aluminium(III) hydride
Aluminium trihydride

Aluminium hydride (also known as alane or alumane) is an inorganic compound with the formula Al H₃. It is a colourless pyrophoric solid. Although rarely encountered outside of research laboratories, alane and its derivatives are used as reducing agents in organic synthesis.

Alane is a polymer. Hence, its formula is sometimes represented with the formula (AlH₃)_n. Alane forms numerous polymorphs, which are named α-alane, α’-alane, β-alane, γ-alane, δ-alane, ε-alane and ζ-alane. α-Alane has a cubic or rhombohedral morphology, whereas α’-alane forms needle-like crystals and γ-alane forms a bundle of fused needles. Alane is soluble in THF and ether. The rate of the precipitation of solid alane from ether varies with the preparation method.
The crystal structure of α-alane has been determined and features aluminium atoms surrounded by 6 hydrogen atoms that bridge to 6 other aluminium atoms. The Al-H distances are all equivalent (172pm) and the Al-H-Al angle is 141°.

α-Alane is the most thermally stable polymorph. β-alane and γ-alane are produced together, and convert to α-alane upon heating. δ, ε, and θ-alane are produced in still other crystallization conditions. Although they are less thermally stable, δ, ε, and θ polymorphs do not convert into α-alane upon heating.

Monomeric AlH₃ has been isolated at low temperature in a solid noble gas matrix and shown to be planar. The dimer Al₂H₆ has been isolated in solid hydrogen. It is isostructural with diborane (B₂H₆) and digallane (Ga₂H₆).

Aluminium hydrides and various complexes thereof have long been known. Its first synthesis published in 1947, and a patent for the synthesis was assigned in 1999. Aluminium hydride is prepared by treating lithium aluminium hydride with aluminium trichloride. The procedure is intricate, attention must be given to the removal of lithium chloride.

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Wikipedia