Copper(I) hydroxide

Copper(I) hydroxide

Names
Other names Cuprous hydroxide; Copper monohydroxide
Identifiers
CAS Number	19650-79-4
3D model (JSmol)	Interactive image
ChemSpider	8031144
ECHA InfoCard
E number
PubChem CID	9855444
CompTox Dashboard (EPA)	{{#property:P3117}}
InChI InChI=1S/Cu.H2O/h;1H2/q+1;/p-1 Key: ZMHWUUMELDFBCZ-UHFFFAOYSA-M
SMILES [OH-].[Cu+]
Properties
Chemical formula	CuOH
Molar mass	80.55 g/mol
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Copper(I) hydroxide is the inorganic compound with the chemical formula of CuOH. Little evidence exists for its existence. A similar situation applies to the monohydroxides of gold(I) and silver(I). Solid CuOH has been claimed however as an unstable yellow-red solid. The topic has been the subject of theoretical analysis. Copper(I) hydroxide would also be expected to easily oxidise to copper(II) hydroxide:

4CuOH + 2 H₂O + O₂ → 4Cu(OH)₂

It would also be expected to rapidly dehydrate:

2CuOH → Cu₂O + H₂O

Solid CuOH would be of interest as a possible intermediate in the formation of copper(I) oxide (Cu₂O), which has diverse applications, e.g. applications in solar cells.

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.

Cu(OH)−2 → CuOH + OH⁻

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 C_s. 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

Structure of a CuOH(IPr) complex. Color code: blue = N, copper = Cu, red = O, white = C, H.

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 [Cu(IPr)]₂OH]⁺ (as its BF−4 salt)) and the aquo complex [Cu(IPr)]OH₂]⁺ (as its SbF−6) have been characterized by X-ray crystallography.