Formation of a nona­nuclear copper(II) cluster with 3,5-di­methyl­pyrazolate starting from an NHC complex of copper(I) chloride

The complete nona­nuclear cluster in bis­[1,3-bis­(2,6-di­methyl­phen­yl)imid­azol­ium] di-μ-chlorido-tetra­chlorido­octa­kis­(μ-3,5-di­methyl­pyrazolato)hexa-μ3-hydroxido-nona­copper(II) chloro­form disolvate, [HIXy]2[Cu9(μ-pz*)8(μ3-OH)6(μ2-Cl)2Cl4]·2CHCl3 or (C19H21N2)2[Cu9(C5H7N2)8Cl6(OH)6]·2CHCl3, where pz* is the 3,5-di­methyl­pyrazolyl anion, C5H7N2−, and HIXy is the 1,3-bis­(2,6-di­methyl­phen­yl)imidazolium cation, C19H21N2+, is generated by a crystallographic centre of symmetry with a square-planar CuII ion bound to four μ3-OH ions lying on the inversion centre. Of the four remaining unique CuII atoms, three adopt CuN2O2Cl square-pyramidal coordination geometries with the chloride ion in the apical position and one has a distorted CuN2OCl tetra­hedral geometry. The dianionic nona­nuclear core can be described as a 24-membered [CuNN]8 ring that contains a Cu9O6Cl6 core. The cluster features three intra­molecular O—H⋯Cl hydrogen bonds. In the crystal, weak C—H⋯N and C—H⋯Cl inter­actions link the components. Polynuclear paramagnetic clusters of this type are of considerable inter­est due to their relevance to both the bioinorganic and single-mol­ecule magnets research fields.