Copper Complexes with New Pyridylpyrazole Based Ligands

Abstract

We report the synthesis, characterization, and crystal structures of new ligands of the pyridinylpyrazole type, i.e., 3,5-bis(4-butoxyphenyl)-1-(pyridin-2-yl)-1H-pyrazole (L1) and 3,5-bis(4-phenoxyphenyl)-1-(pyridin-2-yl)-1H-pyrazole (L2) (Scheme 1), and the study of their coordination behavior towards CuI and CuII. The versatility of this type of ligand, which can give access to different coordination spheres about the metal center, depending on the nature of the copper starting material used in the preparation of the complexes (Scheme 2), is illustrated. Thus, pseudo-tetrahedral CuI as well as six-coordinated tetragonal and distorted tetragonal pyramidal CuII derivatives were obtained for [Cu(L)2]PF6, [Cu(Cl)2(L)2] (L=L1, L2), and [Cu(Cl)(L1)2]PF6, respectively. We also present a crystallographic support of a distorted octahedral cis-bis(tetrafluoroborato-κF)copper(II) compound found for [Cu(BF4)2(L1)2] (3).