Copper (II) metallocycles as anions receptors. Further studies on their synthesis, spectroscopic and spectrometric characterization in solution

Copper (II) metallocycles as anions receptors. Further studies on their synthesis, spectroscopic and spectrometric characterization in solution Rossana Galassia, Camille S. Oumaroua, Alfredo Burinia, Massimiliano Lupacchinia, Stefania Pucciarellib a School of Science and Technology, Università di Camerino, Via Sant’Agostino 1, 62032, Camerino, Italia b School of Biosciences and Biotechnology, University of Camerino, Via Gentile III da Varano, 1, 62032 Camerino, Italy camillesimon.oumarou@unicam.it Halide-centered hexanuclear, anionic copper (II) pyrazolate complexes [trans-Cu6{(3,5-CF3)2pz}6(OH)6X]-, X= Cl, Br, I can be isolated in a good yield from the redox reaction of the trinuclear copper(I) pyrazolate complex [µ-Cu3{(3,5-CF3)2pz}3] with a halide source such as Ph3PAuCl, [Bu4N]X, X= Cl, Br or I or PPN(NO2) where PPN is bis(triphenylphosphoranylidene)ammonium [1]. We reported in this work a new route for the synthesis of the [trans-Cu6{(3,5-CF3)2pz}6(OH)6X] starting from the neutral 3,5-(CF3)2pzH. The reactions showed lower yields but fast conversion to the corresponding halide centered metallocycles. A water centered metallocycle was obtained too. The nature of the molecule inside the cavity was discussed by IR spectroscopy, X-ray structural data and by determining the rate constant of the water exchange reaction in acetone solution. The mechanism likely involves the formation of pyrazoles self-aggregates by intermolecular hydrogen bonding. From data analysis, we can assume that the cavity is very affine for chloride and bromide but scarcely selective, while is slightly less affine for iodide. [1] A. A. Mohamed, S. Ricci, A. Burini, R. Galassi Inorg. Chem. 2011, 50, 1014-1020.