Reactions between CuCl₂ and the functionalized scorpionate 2,2,2-tris(1-pyrazolyl)ethanol HOCH₂C(pz)₃1 (pz = pyrazolyl) or 2,2,2-tris(1-pyrazolyl)ethyl methanesulfonate CH₃SO₂OCH₂C(pz)₃2 yield the corresponding water soluble Cu^II complexes [CuCl₂{HOCH₂C(pz)₃}] 3 or [CuCl₂{CH₃SO₂OCH₂C(pz)₃}]₂4. In 3 the scorpionate ligand shows the typical N,N,N-coordination mode, whereas in the dinuclear complex 4 it binds the metal as a bidentate species. Compounds 1-4 have been characterized by IR, far-IR, elemental analysis and (for 2-4) single crystal X-ray diffraction. The new scorpionate complexes 3 and 4 are shown to act as catalyst precursors for the peroxidative oxidation of cyclohexane to cyclohexanol (main product) and cyclohexanone, under mild conditions (at room temperature and using an aqueous solution of H₂O₂) reaching TON values up to 186 in NCMe/H₂O. Their hydrosolubility allows them to operate also in pure aqueous media (without any organic solvent, although less effectively), a rare feature of significance towards a green alkane oxidation process.

The V-scorpionate vanadium complexes [VCl₃{HC(pz)₃}] (pz = pyrazolyl) and [VCl₃{SO₃C(pz)₃}] catalyze cyclohexane oxidation with dioxygen, to cyclohexanol (the main product) and cyclohexanone, under solvent-free conditions. [VCl₃{HC(pz)₃}] provides the best activity (13 % conversion into the ketone and alcohol, with high selectivity, at the O₂ pressure of 15 atm, at 140 ºC, 18 h reaction time). The reaction is further promoted (to 15 % conversion) by pyrazinecarboxylic acid (PCA). The use of C- or O-radical traps supports the involvement of a free-radical reaction mechanism. Several reaction parameters have been varied in a systematic study, directed toward optimization of the process.