Abstract:The new half-sandwich scorpionate complexes [hydridotris(1-pyrazolyl)methane]vanadium trichloride, ([VCl 3 {HC(pz) were synthesized, characterized and shown to act, as well as the related (tripyrazolylmethane)copper dichloride, [CuCl 2 {HC(pz) 3 }] 6, as selective catalysts (or catalyst precursors) for the peroxidative oxidation (with hydrogen peroxide) of cyclohexane to cyclohexanol and cyclohexanone, under mild conditions (at room temperature and using an aqueous solution of H 2 O 2 ). The iron complexes are the most active ones (reaching TON values up to ca. 690), the effects of a variety of factors are reported and the reaction is shown to proceed via both C-and O-centred radical mechanisms, conceivably involving a metal-based oxidant.

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Coupling five rigid or flexible bis(pyrazolato)-based tectons with late transition metal ions allowed us to isolate 18 coordination polymers (CPs). As assessed by thermal analysis, all of them possess a remarkable thermal\ud stability, their decomposition temperatures lying in the range of 340−500 °C. As demonstrated by N2 adsorption measurements at 77 K, their Langmuir specific surface areas span the rather vast range of 135−1758 m2/g, in agreement with the porous or dense polymeric architectures retrieved by powder X-ray diffraction structure solution methods. Two representative families of CPs, built up with either rigid or flexible spacers, were tested as catalysts in (i) the microwave-assisted\ud solvent-free peroxidative oxidation of alcohols by t-BuOOH, and (ii) the peroxidative oxidation of cyclohexane to cyclohexanol and cyclohexanone by H2O2 in acetonitrile. Those CPs bearing the rigid spacer, concurrently possessing higher specific surface areas, are more active than the corresponding ones with the flexible spacer. Moreover, the two copper(I)-containing CPs investigated exhibit the highest efficiency in both reactions, leading selectively to a maximum product yield of 92% (and TON up to 1.5 × 103) in the oxidation of 1-phenylethanol and of 11% in the oxidation of cyclohexane, the latter value being higher than that granted by the current industrial process