Copper(I) hydroxide

Solid CuOH

Theoretical calculations predict that CuOH would be stable. Specifically, the dissociation of Cu(OH)2− leading to CuOH is subject to an energy of 62 ± 3 kcal/mol. :

Without evidence for its existence, CuOH has been invoked as a catalyst in organic synthesis

Gaseous CuOH

Gaseous CuOH has been characterized spectroscopically using intracavity laser spectroscopy, single vibronic level emission, and microwave spectroscopic detection.

CuOH is calculated to be bent, with the point group Cs. In this case, the bond distance of the Cu-O bond was 1.818 Å and the bond distance of the O-H bond was 0.960 Å. The bond angle for this geometry was 131.9°. The compound is highly ionic in character, which is why this angle is not exactly 120°. Structural parameters for linear CuOH have also been examined computationally.

Ligand-stabilized Cu(I) hydroxides

Although simple CuOH compounds are fairly elusive or restricted to the gas-phase within spectrometers, some derivatives are well characterized.

Specifically cuprous hydroxides have been prepared using bulky NHC co-ligands. In addition to Cu(IPr)OH, the dimer (as its salt)) and the aquo complex (as its ) have been characterized by X-ray crystallography.

References

References

1. (2013). "Cuprous hydroxide in a solid form: does it exist?". Dalton Transactions.
2. (2011). "Thermodynamics of stable and metastable Cu-OH compounds.". Solid State Phenomena.
3. (2006). "Thin film deposition of Cu₂O and Application for Solar Cells". Solar Energy.
4. (1984). "Molecular Structure of Copper (I) Hydroxide and Copper Hydroxide (1-) (Cu (OH)₂⁻). An ''ab initio'' Study.". The Journal of Physical Chemistry.
5. (2019). "Tandem Reaction of Heterocyclic Ketene Aminals with Diazoesters: Synthesis of Pyrimidopyrrolidone Derivatives.". Tetrahedron Letters.
6. (2019). "Rotational Analysis of the [15.1] A "–X~ 1A′ Transition of CuOH and CuOD Observed at High Resolution with Intracavity Laser Spectroscopy.". Journal of Molecular Spectroscopy.
7. (2007). "Single Vibronic Level Emission Spectroscopy and Fluorescence Lifetime of the B~ 1A "→ X~ 1A′ System of CuOH and CuOD.". Chemical Physics Letters.
8. (1999). "Microwave spectroscopic detection of transition metal hydroxides: CuOH and AgOH.". The Journal of Chemical Physics.
9. (2010). "A Versatile Cuprous Synthon: [Cu(IPr)(OH)] (IPr = 1,3 Bis(diisopropylphenyl)imidazol-2-ylidene)". Organometallics.
10. (2014). "[{Cu(IPr)}2(μ-OH)][BF4]: Synthesis and Halide-Free CuAAC Catalysis". Chemical Communications.
11. (2021). "Synthesis and Characterization of N-Heterocyclic Carbene–M⋯OEt₂ Complexes (M = Cu, Ag, Au). Analysis of Solvated Auxiliary-Ligand Free [(NHC)M]⁺ Species". Physical Chemistry Chemical Physics.