New dinuclear Pd(II) complex with pyrazolate bridges. Synthesis and crystal structure of [Pd(μ-pz)(pzH)2]2(BF4)2 (pzH=pyrazole)

Dinuclear pyrazolate-bridged Pd(II) complex [Pd(μ-pz)(pzH)2]2(BF4)2 has been prepared by treatment of pyrazole (pzH), sodium ethoxide, and [Pd(CH3CN)4](BF4)2. The new complex has been characterised by elemental analyses, IR, 1H NMR, 13C{1H} NMR, and single crystal X-ray diffraction methods. This structure shows two palladium atoms bridged by two pyrazolate ligands. The square-planar geometry of each Pd atom is completed by two pyrazole ligands. The six-membered dipalladacycle formed by the two Pd atoms and the two bridging pyrazolate ligands adopt a distorted boat-like conformation. This compound is the first example of a dinuclear Pd(II)–pyrazolate homoleptic complex.