iridium

Also known as Ir, element 77

Iridium is a chemical element; it has the symbol Ir and atomic number 77. This very hard, brittle, silvery-white transition metal of the platinum group is considered the second-densest naturally occurring metal (after osmium), with a density of as defined by experimental X-ray crystallography. 191Ir and 193Ir are the only two naturally occurring isotopes of iridium, as well as the only stable isotopes; the latter is the more abundant. It is one of the most corrosion-resistant metals, even at temperatures as high as .

OverviewAI-generated

Iridium is a chemical element with the symbol Ir and atomic number 77. It has a mass of 192.217 and an electronegativity of 2.2. The element was discovered in 1803. Its chemical formula is Ir, and it is represented by the Unicode character "銥".

The ionic radius of iridium is 0.68. In chemical databases, it is associated with the PubChem CID 23924 and has a molecular weight of 192.22. The structure is described by the canonical SMILES "[Ir]" and the InChIKey GKOZUEZYRPOHIO-UHFFFAOYSA-N. It has zero hydrogen bond donors and acceptors, and a topological polar surface area of 0.

Iridium is referenced by 982 other encyclopedia articles. Medical literature contains 13,693 entries related to the query "iridium". The subject is categorized under the Commons category "Iridium" and has a corresponding gallery.

Synthesized by Vinony from 23 facts across 4 sources: Wikidata, PubChem, PubMed, Vinony graph. Generated from structured data (not the Wikipedia text) and checked against those facts — may still contain errors.

Chemical data

Formula: Ir
Molecular weight: 192.22 g/mol
IUPAC name: iridium
SMILES: [Ir]
InChIKey: GKOZUEZYRPOHIO-UHFFFAOYSA-N
Polar surface area: 0 Å²
H-bond donors: 0
H-bond acceptors: 0
Formal charge: 0

via PubChem

Research

13,693 papers

Cytotoxic Organometallic Iridium(III) Complexes.ReviewMolecules (Basel, Switzerland) · 2025Kostova IDOI: 10.3390/molecules30040801
Iridium and IrO(x) nanoparticles: an overview and review of syntheses and applications.ReviewAdvances in colloid and interface science · 2022Quinson JDOI: 10.1016/j.cis.2022.102643
Iridium(III)-based chemosensors for the detection of metal ions.ReviewMethods (San Diego, Calif.) · 2019Ma DL, Wong SY, Kang TS et al.DOI: 10.1016/j.ymeth.2019.02.013
Iridium metal complex targeting oxidation resistance 1 protein attenuates spinal cord injury by inhibiting oxidative stress-associated reactive oxygen species.Redox biology · 2023Peng C, Luo J, Wang K et al.DOI: 10.1016/j.redox.2023.102913
Iridium in Cancer Therapy: A New Frontier in Metal-Based Medicine.ReviewZhongguo ying yong sheng li xue za zhi = Zhongguo yingyong shenglixue zazhi = Chinese journal of applied physiology · 2025Kumbhare MR, Porje R, Shaikh ADOI: 10.62958/j.cjap.2025.034
Recent Advances in Organometallic NIR Iridium(III) Complexes for Detection and Therapy.ReviewMolecules (Basel, Switzerland) · 2024Jing S, Wu X, Niu D et al.DOI: 10.3390/molecules29010256
Iridium(III) complexes as novel theranostic small molecules for medical diagnostics, precise imaging at a single cell level and targeted anticancer therapy.ReviewEuropean journal of medicinal chemistry · 2024Szymaszek P, Tyszka-Czochara M, Ortyl JDOI: 10.1016/j.ejmech.2024.116648
Iridium-based Polymeric Multifunctional Imaging Tools for Biochemistry.ChemPlusChem · 2024Sansee A, Kostka L, Marcalíková A et al.DOI: 10.1002/cplu.202300647

via PubMed

~28 min read

Encyclopedic overview

28 sections

Contents

Characteristics
Physical properties
Chemical properties
Isotopes
Chemistry
Oxidation states
Binary compounds
Complexes
Organoiridium chemistry
History
Platinum group
Discovery
Metalworking and applications
Occurrence
Marine oceanography
Cretaceous–Paleogene boundary presence
Production
Applications
Metal and alloys
Catalysis
Medical imaging
Photocatalysis and OLEDs
Scientific
Historical
Precautions and hazards
Notes
References
External links

Iridium was discovered in 1803 in the acid-insoluble residues of platinum ores by the British chemist Smithson Tennant. The name iridium, derived from the Greek word iris (rainbow), refers to the various colors of its compounds. Iridium is one of the rarest elements in Earth's crust, with an estimated annual production of only in 2023.

Excerpted from Wikipedia’s “iridium” article, available under the CC BY-SA 4.0 licence.