On the path to bulk FeH2: Synthesis and magnetic properties of amorphous iron (II) hydride

• Amorphous Fe(II) hydride material approximating FeH2 has been isolated as a powder.
• Moderate reaction conditions of 100 bar H2 and 298 K used.
• Magnetic and hydrogen storage properties were investigated.
• The mixed phase material is ferromagnetic.
• Magnetic susceptibility of 1.25 Bohr magnetons per formula unit at 10 K.

An amorphous Fe(II) hydride material approximating FeH2 in composition (FeH2−xRx(Et2O)y where R = mesityl) has been isolated as a bulk powder in the solid state. This was accomplished under moderate reaction conditions by the reaction of bis(mesityl) iron(II) in toluene and hydrogen gas at 100 bar and 298 K to give a 1:5 mixed phase amorphous material of Fe(0) and the iron (II) hydride. This represents an important advance because FeH2 has never been synthesised in bulk form. The material shows ferromagnetic behaviour with a magnetic susceptibility of 1.25 Bohr magnetons per formula unit at 10 K.