An octa-nuclear nickel(II) pyrazolate cluster with a cubic Ni core and its methyl- and -octyl-functionalized derivatives.

The mol-ecular and crystal structure of a discrete [Ni(μ-OH)(μ-4-pz)] ( = H; pz = pyrazolate anion, CHN ) cluster with an unprecedented, perfectly cubic arrangement of its eight Ni centers is reported, along with its lower-symmetry alkyl-functionalized ( = methyl and -oct-yl) derivatives. Crystals of the latter two were obtained with two identical counter-ions (BuN), whereas the crystal of the complex with the parent pyrazole ligand has one MeN and one BuN counter-ion. The methyl derivative incorporates 1,2-di-chloro-ethane solvent mol-ecules in its crystal structure, whereas the other two are solvent-free. The compounds are tetra-butyl-aza-nium tetra-methyl-aza-nium hexa-μ-hydroxido-dodeca-μ-pyrazolato--octa-nickel, (CHN)(CHN)[Ni(CHN)(OH)] or (BuN)(MeN)[Ni(μ-OH)(μ-pz)] (), bis-(tetra-butyl-aza-nium) hexa-μ-hydroxido-dodeca-μ-(4-methyl-pyrazolato)--octa-nickel 1,2-di-chloro-ethane 7.196-solvate, (CHN)[Ni(CHN)(OH)]·7.196CHCl or (BuN)[Ni(μ-OH)(μ-4-Mepz)]·7.196(ClCHCHCl) (), and bis-(tetra-butyl-aza-nium) hexa-μ-hydroxido-dodeca-μ-(4-octylpyrazolato)--octa-nickel, (CHN)[Ni(CHN)(OH)] or (BuN)[Ni(μ-OH)(μ-4-Octpz)] (). All counter-ions are disordered (with the exception of one BuN in ). Some of the octyl chains of (the crystal is twinned by non-merohedry) are also disordered. Various structural features are discussed and contrasted with those of other known [Ni(μ-OH)(μ-4-pz)] complexes, including extended three-dimensional metal-organic frameworks. In all three structures, the Ni units are lined up in columns.