Magnesium iron hexahydride is an inorganic compound with the formula Mg₂FeH₆. It is a green

diamagnetic Diamagnetic materials are repelled by a magnetic field; an applied magnetic field creates an induced magnetic field in them in the opposite direction, causing a repulsive force. In contrast, paramagnetic and ferromagnetic materials are attracted ...

solid that is stable in dry air. The material is prepared by heating a mixture of powdered

magnesium Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...

and

iron Iron () is a chemical element with Symbol (chemistry), symbol Fe (from la, Wikt:ferrum, ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 element, group 8 of the periodic table. It is, Abundanc ...

under high pressures of

hydrogen Hydrogen is the chemical element with the symbol H and atomic number 1. Hydrogen is the lightest element. At standard conditions hydrogen is a gas of diatomic molecules having the formula . It is colorless, odorless, tasteless, non-toxic ...

: :2 Mg + Fe + 3 H₂ → Mg₂FeH₆

Structure

The compound is

isomorphous In mathematics, an isomorphism is a structure-preserving mapping between two structures of the same type that can be reversed by an inverse mapping. Two mathematical structures are isomorphic if an isomorphism exists between them. The word is ...

with K₂PtCl₆, i.e., their connectivities and structures are the same. The eH₆sup>4− centre adopts octahedral molecular geometry with Fe-H distances of 1.56 Å. The Mg²⁺ centres are bound to the faces of the octahedron, with Mg-H distances of 2.38 Å. Several related compounds are known including salts of uH₆sup>4−, sH₆sup>4−, and tH₆sup>2− anions.

Soluble derivatives

Although Mg₂FeH₆ is not soluble in ordinary solvents, related derivatives are. For example, the related salt Mg₄Br₄(

THF Tetrahydrofuran (THF), or oxolane, is an organic compound with the formula (CH2)4O. The compound is classified as heterocyclic compound, specifically a cyclic ether. It is a colorless, water- miscible organic liquid with low viscosity. It is ...

)₄FeH₆ is soluble as are related alkoxides. Measurements on such compounds suggest that the

hydride In chemistry, a hydride is formally the anion of hydrogen( H−). The term is applied loosely. At one extreme, all compounds containing covalently bound H atoms are called hydrides: water (H2O) is a hydride of oxygen, ammonia is a hydride ...

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's elec ...

exerts a weaker crystal field than

cyanide Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...

.R.B. King "Structure and bonding in homoleptic transition metal hydride anions" Coordination Chemistry Reviews, 2000, vol. 200–202, p. 813–829.

References

{{Iron compounds Metal hydrides Magnesium compounds Iron(II) compounds Iron complexes