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--chlorido-tetrachloridooctakis(-3,5-dimethylpyrazolato)hexa-3-
hydroxido-nonacopper(II) chloroform disolvate, [HIXy]2[Cu9(-pz*)8(3-
OH)6(2-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 3-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.