Cyclopentadienylindium(I), C₅H₅In, is an organoindium compound containing

indium Indium is a chemical element with the symbol In and atomic number 49. Indium is the softest metal that is not an alkali metal. It is a silvery-white metal that resembles tin in appearance. It is a post-transition metal that makes up 0.21 parts p ...

in the +1 oxidation state. Commonly abbreviated to CpIn, it is a

cyclopentadienyl complex A cyclopentadienyl complex is a coordination complex of a metal and cyclopentadienyl groups (, abbreviated as Cp−). Cyclopentadienyl ligands almost invariably bind to metals as a pentahapto (''η''5-) bonding mode. The metal–cyclopentadien ...

with a half-sandwich structure. It was the first (1957) low valent organoindium compound reported.

Preparation and chemistry

CpIn can be readily prepared by reacting indium(I) chloride with cyclopentadienyllithium: :InCl + CpLi → CpIn + LiCl InCp reacts with BF₃, BCl₃, BBr₃, BI₃ and

trimethylborane Trimethylborane (TMB) is a toxic, pyrophoric gas with the formula B(CH3)3 (which can also be written as Me3B, with Me representing methyl). Properties As a liquid it is colourless. The strongest line in the infrared spectrum is at 1330 cm� ...

B(CH₃)₃ to form adducts, e.g.: :CpIn + BF₃ → CpIn·BF₃ In these adducts the bonding of the Cp ligand to the indium atom changes from η⁵ (π complexing) to η¹ (σ bonding). Salts containing the InX₂⁻ anion containing indium in the +1 oxidation state have been prepared, for example: :CpIn +

HCl HCL may refer to: Science and medicine * Hairy cell leukemia, an uncommon and slowly progressing B cell leukemia * Harvard Cyclotron Laboratory, from 1961 to 2002, a proton accelerator used for research and development * Hollow-cathode lamp, a spe ...

+ N(Et₄)Cl → N(Et₄)InCl₂+ C₅H₆

Structure and bonding

Solid CpIn is polymeric consisting of zigzag chains of alternating indium atoms and C₅H₅ units. Two indium atoms interact with the opposite faces of each C₅H₅⁻ ring, nearly perpendicularly to the ring plane, and two rings interact with each indium atom, forming an angle of about 128°. In the CpIn monomer present in the vapour phase the indium atom sits on the central axis of the

aromatic In chemistry, aromaticity is a chemical property of cyclic ( ring-shaped), ''typically'' planar (flat) molecular structures with pi bonds in resonance (those containing delocalized electrons) that gives increased stability compared to satur ...

cyclopentadienyl anion, C₅H₅⁻. Bonding studies have shown that the aromatic ring electrons of the cyclopentadienyl anion interact with the indium 5s and 5p

atomic orbital In atomic theory and quantum mechanics, an atomic orbital is a function describing the location and wave-like behavior of an electron in an atom. This function can be used to calculate the probability of finding any electron of an atom in any spe ...

s, and that the lone pair on the indium atom is a dominant feature.

References

{{Indium compounds Indium(I) compounds Cyclopentadienyl complexes