Physical world and mathematics

Iron tetraphenylporphyrin

Iron tetraphenylporphyrin (FeTPP) is an iron complex of a porphyrin ligand, the parent compound of a widely studied family of catalysts for reducing carbon dioxide to carbon monoxide.

Iron thiophosphate

Iron thiophosphate (FePS3) is a layered van der Waals compound of iron, phosphorus, and sulfur that stays antiferromagnetic even as a single layer, nicknamed "magnetic graphene".

Iron-59

Iron-59 is a radioactive isotope of iron with a half-life of 44.5 days, used since 1950 as a tracer for studying iron metabolism in humans.

Iron-based superconductors, also called ferropnictides, are layered compounds of iron and pnictogen or chalcogen sheets, discovered in 2008, that superconduct at up to about 57 K through magnetic pairing.

Iron-catalyzed asymmetric cross-coupling

Iron-catalyzed asymmetric cross-coupling is a carbon–carbon bond-forming reaction using a chiral iron catalyst, pioneered from Kochi's 1970s work and valued for iron's low cost and nontoxicity.

Iron-catalyzed asymmetric hydrogenation

Iron-catalyzed asymmetric hydrogenation is the reduction of ketones and imines using iron complexes to give enantioenriched products, developed since 2004 as an alternative to expensive ruthenium and iridium catalysts.

Iron-catalyzed C-H functionalization

Iron-catalyzed C-H functionalization uses iron complexes to turn unreactive carbon-hydrogen bonds directly into carbon-carbon or carbon-heteroatom bonds, favored for iron's low cost, abundance, and low toxicity.

Iron-catalyzed C–H activation

Iron-catalyzed C–H activation is the conversion of inert carbon–hydrogen bonds into carbon–carbon or carbon–heteroatom bonds using iron catalysts, replacing precious metals; its drawbacks include high temperatures and lower selectivity.

Iron-catalyzed C–H amination

Iron-catalyzed C–H amination is a chemical method in which an iron compound converts a carbon–hydrogen bond of an organic molecule directly into a carbon–nitrogen bond.

Iron-catalyzed directed C–H activation

Iron-catalyzed directed C–H activation is a family of organic reactions where a directing group guides an iron catalyst to cleave and functionalize a specific C–H bond directly.

Iron-catalyzed N2-to-NH3 conversion

Iron-catalyzed N2-to-NH3 conversion reduces atmospheric dinitrogen to ammonia using iron catalysts, performed industrially in the Haber-Bosch process and achieved molecularly under mild conditions by Peters in 2013.

Iron-cobalt alloy

Iron-cobalt alloy is a soft magnetic material, best known in near-equiatomic compositions that combine the highest saturation magnetization of any material with a high Curie temperature.

Iron(II,III) oxide

Iron(II,III) oxide, also called ferrous ferric oxide or Fe3O4, is the black, strongly magnetic mineral magnetite, a chief iron ore used in steelmaking, pigments, and biomedical nanoparticles.

Iron(II) chloride

Iron(II) chloride, also called ferrous chloride (FeCl₂), is an inorganic iron salt produced as a byproduct of steel pickling and used chiefly as a coagulant in water and wastewater treatment.

Iron(II) oxide

Iron(II) oxide, also called ferrous oxide (FeO), is a rocksalt-structured iron oxide that is always iron-deficient, occurring in nature as the mineral wüstite and serving as a key intermediate in reducing iron ore to metal.

Iron(II) sulfate

Iron(II) sulfate, also known as ferrous sulfate or FeSO4, is a sulfate salt of divalent iron used as an iron supplement, coagulant, and fertilizer ingredient.

Iron(II) sulfide

Iron(II) sulfide, also known as ferrous sulfide, is a compound of iron and sulfur best known as the mineral troilite, common in lunar rocks and iron meteorites.

Iron(III) chloride

Iron(III) chloride (FeCl3), also called ferric chloride or iron trichloride, is an inorganic iron salt whose main commercial use in the United States is water treatment.

Iron(III) hydroxide

Iron(III) hydroxide, also called ferric hydroxide, is the hydroxide of trivalent iron with formula Fe(OH)₃, best known as the brown precipitate from iron(III) salts and base.

Iron(III) oxide

Iron(III) oxide, or ferric oxide (Fe2O3), is the main iron oxide in hematite, the principal iron ore, and gives rust and Martian soil their red color.

Iron(III) oxide-hydroxide

Iron(III) oxide-hydroxide (FeOOH), also called yellow iron oxide, is a family of ferric oxyhydroxide compounds occurring as polymorphs including goethite, the main yellow pigment in ochre.

Iron(III) sulfate

Iron(III) sulfate, also called ferric sulfate, is an inorganic salt of trivalent iron with formula Fe2(SO4)3, a yellow crystalline solid used mainly as a coagulant in water treatment.

Iron(V)-oxo complex

An iron(V)-oxo complex is a coordination compound with an iron center in the +5 oxidation state bound to a terminal oxo ligand, proposed in enzymes like cytochrome P450.

Irosustat

Irosustat, also known as STX64 or Oristusane, is an orally bioavailable, irreversible steroid sulfatase inhibitor investigated as a hormonal anticancer drug for breast, endometrial, and prostate cancer.

Irradiance

Irradiance, symbolized E or Ee, is the radiant flux incident on a surface per unit area, expressed in watts per square meter; sunlight at the top of the atmosphere is about 1361 W m⁻².

Irradiation

Irradiation is the deliberate exposure of a material to ionizing radiation, typically gamma rays, X-rays, or electron beams, to sterilize, preserve, or modify it, leaving no radioactive residue.

Irrational number

An irrational number is a real number that cannot be written as a ratio of two integers; its decimal expansion neither terminates nor repeats, as with √2 and π.

Irrational rotation algebra

The irrational rotation algebra, also called the noncommutative torus, is a universal C-algebra generated by two unitaries with uv = e^(2πiθ)vu; for irrational θ it is simple with a unique trace.

Irreducible element

An irreducible element, also called an atom, is a nonzero, non-unit element of an integral domain that cannot be written as a product of two non-unit elements; it generalizes prime numbers to abstract rings.