An iron hydride is a chemical system which contains iron and hydrogen in some associated form. [1] [2]
Because of the common occurrence of those two elements in the universe, possible compounds of hydrogen and iron have attracted attention. A few molecular compounds have been detected in extreme environments (such as stellar atmospheres) or in small amounts at very low temperatures. The two elements form a metallic alloy above 35,000 standard atmospheres (3.5 GPa) of pressure, that has been advanced as a possible explanation for the low density of Earth's "iron" core. [2] [3] However those compounds are unstable when brought to ambient conditions, and eventually decompose into the separate elements.
Small amounts of hydrogen (up to about 0.08% by weight) are absorbed into iron as it solidifies from its molten state. [4] Although the H2 is simply an impurity, its presence can affect the material's mechanical properties.
Despite the fleeting nature of binary iron hydrides, there are many fairly stable complexes containing iron-hydrogen bonds (and other elements). [5] [6]
Iron and iron-based alloys can form solid solutions with hydrogen, which under extreme pressure may reach stoichiometric proportions, remaining stable even at high temperatures and surviving for a while under ambient pressure, at temperatures below 150K. [7]
Complexes displaying iron–hydrogen bonds include, for example:
Complexes are also known with molecular hydrogen (H
2) ligands.
Methanogens, archaea, bacteria and some unicellular eukaryotes contain hydrogenase enzymes that catalyse metabolic reactions involving free hydrogen, whose active site is an iron atom with Fe–H bonds as well as other ligands. [13]
An iron hydride is a chemical system which contains iron and hydrogen in some associated form. [1] [2]
Because of the common occurrence of those two elements in the universe, possible compounds of hydrogen and iron have attracted attention. A few molecular compounds have been detected in extreme environments (such as stellar atmospheres) or in small amounts at very low temperatures. The two elements form a metallic alloy above 35,000 standard atmospheres (3.5 GPa) of pressure, that has been advanced as a possible explanation for the low density of Earth's "iron" core. [2] [3] However those compounds are unstable when brought to ambient conditions, and eventually decompose into the separate elements.
Small amounts of hydrogen (up to about 0.08% by weight) are absorbed into iron as it solidifies from its molten state. [4] Although the H2 is simply an impurity, its presence can affect the material's mechanical properties.
Despite the fleeting nature of binary iron hydrides, there are many fairly stable complexes containing iron-hydrogen bonds (and other elements). [5] [6]
Iron and iron-based alloys can form solid solutions with hydrogen, which under extreme pressure may reach stoichiometric proportions, remaining stable even at high temperatures and surviving for a while under ambient pressure, at temperatures below 150K. [7]
Complexes displaying iron–hydrogen bonds include, for example:
Complexes are also known with molecular hydrogen (H
2) ligands.
Methanogens, archaea, bacteria and some unicellular eukaryotes contain hydrogenase enzymes that catalyse metabolic reactions involving free hydrogen, whose active site is an iron atom with Fe–H bonds as well as other ligands. [13]