Coordination polymers based on trinuclear and mononuclear copper-pyrazolate building moieties connected by fumarate or 2-methylfumarate ions

By reacting water solutions of pyrazole (Hpz) with copper(II) fumarate or 2-methylfumarate in solvothermal conditions two almost identical trinuclear triangular complexes, [Cu3(μ3-OH)(μ-pz)3{R(COO)2}(Hpz)], [R = CHCH, C(CH3)CH], have been obtained. The two carboxylate groups of both fumarate and 2-methylfumarate show different arrangements, one acting as monotopic ligand while the other one has a ditopic behavior. Thus, in both cases, wavy 2D isomorphous Coordination Polymers (CPs), that further self-assemble through strong H-bonds into two 3D networks, have been obtained. When copper(II) 2-methylfumarate was reacted with pyrazole at r.t. the mononuclear [Cu(Hpz)2(H2O)(2-methylfumarate)·H2O] complex was, in addition, obtained. In this case the bridging dianions produce instead monodimensional CPs that self-assemble into supramolecular tapes mediated by H-bond interactions, involving coordinated and crystallization water molecules. The mononuclear and trinuclear species were preliminary tested as catalysts for the oxidation of styrene by H2O2.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► 2D coordination polymers based on the trinuclear triangular Cu3(μ3-OH)(μ-pz)3 moiety. ► XRD molecular structures of fumarate and 2-methylfumarate CuII coordination polymers. ► CuII coordination polymers as precursors in the catalytic oxidation of styrene. ► 1D coordination polymer of copper(II) 2-methylfumarate.