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Efficient Synthesis of All-Carbon Quaternary Centers via the Conjugate Addition of Functionalized Monoorganozinc Bromides
Published on: May 26, 2019
Bromidobis[3-(1H-pyrazol-1-yl-κN(2))propionamide-κO]copper(II) bromide methanol monosolvate
Thomas Wagner1, Cristian G Hrib, Volker Lorenz
1Chemisches Institut, Otto-von-Guericke-Universität Magdeburg, Universitätsplatz 2, 39106 Magdeburg, Germany.
Abstract:
The title copper(II) N-pyrazolylpropanamide (PPA) complex, [CuBr(PPA)(2)]Br, was obtained in 78% yield by treatment of CuBr(2) with an excess of the ligand in methanol. Crystallization from the mother liquid afforded the title compound, i.e. the methanol solvate [CuBr(C(6)H(9)N(3)O)(2)]Br·CH(3)OH or [CuBr(PPA)(2)]Br·MeOH, as bright green crystals. In the solid state, the title salt comprises isolated [CuBr(PPA)(2)](+) cations, separated bromide ions and methanol of crystallization. In the cation, the central Cu(II) ion is coordinated by two N,O-chelating PPA ligands and one Br(-) ion. The coordination geometry around the Cu(II) ion is distorted trigonal-bipyramidal with the bromide ligand and the amide O atoms occupying the equatorial positions [Cu-Br = 2.4443 (4) Å; Cu-O = 2.035 (2) and 2.179 (2) Å], while the pyrazole N atoms coordinate in the axial positions [Cu-N = 1.975 (2) and 1.976 (2) Å]. In the crystal, the three constituents are linked by N-H⋯Br, O-H⋯Br, and N-H⋯O hydrogen bonds, forming a three-dimensional network.
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