Organoiridium compounds contain iridium-carbon chemical bonds. Compounds with Ir-C bonds are found in oxidation states from 0 to V. For example, oxidation state zero is found in tetrairidium dodecacarbonyl, Ir4(CO)12, which is the most common and stable binary carbonyl of iridium. In this compound, each of the iridium atoms is bonded to the other three, forming a tetrahedral cluster. Some organometallic Ir(I) compounds are notable enough to be named after their discoverers. One is Vaska's complex, IrCl(CO)[P(C6H5) 3]2, which has the unusual property of reversibly binding to dioxygen molecule, O2. Another one is Crabtree's catalyst, a homogeneous catalyst for hydrogenation reactions. Iridium(I) complexes are both square planar, d8 complexes, with a total of 16 valence electrons, which accounts for their reactivity. Many organoiridium compounds are generated from pentamethylcyclopentadienyl iridium dichloride dimer.
The dominant application of organoiridium complexes is as catalysts in the Cativa process for carbonylation of methanol to produce acetic acid Iridium is competitive with rhodium for this large-scale application because of lower operating costs.
In the academic laboratories, iridium complexes are widely studied because its complexes promote C-H activation, but such reactions are not employed in any commercial process. Iridium complexes are highly active for hydrogenation both directly and via transfer hydrogenation. The asymmetric versions of these reactions are widely studied.
|Core organic chemistry||Many uses in chemistry.|
|Academic research, but no widespread use||Bond unknown / not assessed.|