Explain why ${{Cu}^{+}}$ ion is not stable in aqueous solution?

Explain why ${{Cu}^{+}}$ ion is not stable in aqueous solution?
Or
Explain why Cu (I) ion is not known in aqueous solution?

In aqueous solution, copper (I) undergoes disproportionation reaction.
2${{Cu}^{+}}$ (aq) ------> ${{Cu}^{2+}}$ + Cu(s)
The highest stability of ${{Cu}^{2+}}$ ion in aqueous solution is due to negative enthalpy of hydration.
Hence, ${{Cu}^{+}}$ is not known (or unstable) in aqueous solution.