Synthesis of Coordination Polymers and Discrete Complexes from the Reaction of Copper(II) Carboxylates with Pyrazole: Role of Carboxylates Basicity

Abstract

The reaction of select copper­(II) monocarboxylates Cu­(RCOO)2(H2O) x (R = C4H3O, C6H5, H; x = 2, 4) with pyrazole (Hpz), carried out in protic solvents, yields mono- or dinuclear species [Cu­(RCOO)2(Hpz) n ] m (n = 2, 4; m = 1, 2), always accompanied by tri- or hexanuclear derivatives based on the triangular [Cu3(μ3-OH)­(μ-pz)3]2+ fragment. The molecular structures of all isolated compounds have been established through XRD determinations. In some cases, the mono-, or dinuclear species act as secondary building units, self-assembling into 1D or 3D coordination polymers. The hexanuclear benzoate cluster contains coordinated and crystallization MeOH molecules, whose removal generates a crystalline 1D coordination polymer that can be reconverted into the hexanuclear cluster by soaking in MeOH. The relatively high pK b values of carboxylate anions employed in the syntheses are responsible for the preferential formation of mono- or dinuclear species rather than tri- or hexanuclear ones.

Spin Frustrated Pyrazolato Triangular CuII Complex: Structure and Magnetic Properties, an Overview

“…0.7 electrons, although saturation is not fully reached at 5 T (Figure 3). This behavior is typical of systems with a µ 3 -hydroxido moiety with a ground state of S = 1 2 (M = 1 µ B ), that present magnetization values below the expected ones and do not reach saturation, even at high fields [22,39]. Comparing the experimental data with those calculated using the PHI program (see below) for 1−Cu 3 shows a good agreement between them.…”

“…Triangular Cu II complexes have been largely studied in the literature, and among them, several systems present a µ 3 −X − (X = Cl − , Br − , OH − , O 2− ) bridging unit that, together with other organic auxiliary ligands enables obtaining very stable systems [1][2][3][4][5]. Due to their high stability, these triangular fragments can be used as secondary building units (SBU) in constructing several coordination polymers or MOF systems [6][7][8][9].…”

Research of the influence of anions in complexes [CuPhen(Hpz)2X2] (X = CF3COO−, Otf−, Cl−) on the structure and bioactivity

“…When interacting with salts of strong acids, pyrazole is coordinated monodentately. 12 In continuation of our research, we decided to study the effect of the anion on the biological activity of copper complexes containing coordinated phenanthroline and pyrazole. The aim of this work is to obtain copper complexes containing coordinated phenanthroline and pyrazole and anions of different acid strengths -trifluoroacetic, trifluoromethanesulfonic and hydrochloric, as well as to study the effect of the anion on the structure and antiproliferative properties.…”