Unexpected formation and crystal structure of tetra-kis-(1H-pyrazole-κN (2))-palladium(II) dichloride.

The title salt, [Pd(C3H4N2)4]Cl2, was obtained unexpectedly by the reaction of palladium(II) dichloride with equimolar amounts of 1-chloro-1-nitro-2,2,2-tris-(pyrazol-yl)ethane in methanol solution. The Pd(2+) cation is located on an inversion centre and has a square-planar coordination sphere defined by four N atoms of four neutral pyrazole ligands. The average Pd-N distance is 2.000 (2) Å. The two chloride anions are not coordinating to Pd(2+). They are connected to the complex cations through N-H⋯Cl hydrogen bonds. In addition, C-H⋯Cl hydrogen bonds are observed, leading to a three-dimensional linkage of cations and anions.