A new rare-earth metal acylpyrazolonate containing the Zundel ion H5O2+stabilized by strong hydrogen bonding

Abstract A new luminescent europium derivative [H 5 O 2 ][Eu(Q Cy ) 4 ] (1) (HQ Cy  = 1-phenyl-3-methyl-4-cyclohexanecarbonylpyrazole-5-one), achievable in high yield, characterized by high thermal stability, ionic in acetone and ethanol solution, contains the Zundel cations H 5 O 2 + stabilized by strong hydrogen bonding with the N atoms of the anionic heterocyclic ligand (Q Cy ).