Bis[hydro­tris(4-chloro-3,5-dimethyl­pyrazolyl)borato]nickel(II)

The title compound, [Ni(C₁₅H₁₉BCl₃N₆)₂] or Ni(Tp*^Cl)₂, adds to the list of structurally characterized bis­(tris­pyrazolyl)borate-nickel(II) complexes. The two facially coordinating N-donor Tp*^Cl ligands impose pseudo-octa­hedral coordination on the nickel(II) center. The asymmetric unit consists of two half mol­ecules, primarily differing in the torsion angles of the coordinated pyrazole rings relative to the central B-Ni-B axis of the mol­ecules; each molecule is centrosymmetric. An average overall Ni-N distance of 2.104 (15) Å is observed, typical of octa­hedral NiN₆ coordination spheres and this class of compound. The title compound readily forms good quality crystals, while its 4-H analog, Ni(Tp*)₂, does not. This characteristic is attributed to close contacts between the pyrazole 4-chloro-substituents on adjacent mol­ecules.