Tetrakis(acetonitrile)copper(I) hexafluorophosphate

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Tetrakis(acetonitrile)copper(I) hexafluorophosphate
Structural formulas of the tetrakis(acetonitrile)copper(I) cation and the hexafluorophosphate anion
Space-filling models of the component ions of tetrakis(acetonitrile)copper(I) hexafluorophosphate
Names
IUPAC name
Tetrakis(acetonitrile)copper(I) hexafluorophosphate
Identifiers
64443-05-6 YesY
Properties
[Cu(CH3CN)4]PF6
Molar mass 372.7198 g/mol
Appearance White powder
Melting point 160 °C (320 °F; 433 K)
Vapor pressure {{{value}}}
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Tetrakis(acetonitrile)copper(I) hexafluorophosphate is a coordination compound with the formula [Cu(CH3CN)4]PF6. It is a colourless solid that is used in the synthesis of copper complexes.[1]

Structure

As confirmed by X-ray crystallographic studies, copper(I) ion is coordinated to four almost linear acetonitrile ligands in a nearly ideal tetrahedral geometry.[2] Related complexes are known with other anions including the perchlorate, tetrafluoroborate, and nitrate. With the weakly coordinating anion B(C6F5)4, salts of [Cu(CH3CN)2]+ are obtained.[1]

The acetonitrile ligands protect the Cu+ ion from oxidation to Cu2+. However, acetonitrile is not bound very strongly to the copper ion, thus the complex is a useful source of Cu(I).

Synthesis

The cation was first reported in 1923 with a nitrate anion as a byproduct of the reduction of silver nitrate with a suspension of copper powder in acetonitrile.[3] [Cu(CH3CN)4]PF6 is generally produced by the addition of HPF6 to a suspension of copper(I) oxide in acetonitrile:[4]

Cu2O + 2 HPF6 + 8 CH3CN → 2 [Cu(CH3CN)4]PF6 + H2O

The reaction is highly exothermic, and may bring the solution to a boil. Upon crystallization, the resulting microcrystals should be white, though a blue tinge is common, indicating the presence of a Cu2+ species.[4]

Reactions and applications

As the coordinated acetonitrile ligands may be displaced in other solvents, the [Cu(CH3CN)4]PF6 compound may serve as a precursor in the non-aqueous syntheses of other Cu(I) compounds.[4]

Water-immiscible organic nitriles have been shown to selectively extract Cu2+ from aqueous chloride solutions.[5] Through this method, copper can be separated from a mixture of other metals. Dilution of acetonitrile solutions with water induces disproportionation:

2 [Cu(CH3CN)4]+ + 6 H2O → [Cu(H2O)6]2+ + Cu + 8 CH3CN

References

  1. 1.0 1.1 Silvana F. Rach, Fritz E. Kühn "Nitrile Ligated Transition Metal Complexes with Weakly Coordinating Counteranions and Their Catalytic Applications" Chem. Rev., 2009, volume 109, pp 2061–2080. doi:10.1021/cr800270h
  2. Lua error in package.lua at line 80: module 'strict' not found.J. R. Black, W. Levason and M. Webster "Tetrakis(acetonitrile-N)copper(I) Hexafluorophosphate(V) Acetonitrile Solvate"Acta Crystallogr. (1995). C51, pp. 623-625. doi:10.1107/S0108270194012527
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