Pyrazolato-bridged binuclear palladium(II) compounds: synthesis and crystal structure

Abstract

Pyrazolato-bridged binuclear palladium(II) complexes of the type [Pd₂X₂(µ-L–L)₂(PR₃)₂][L–L = pz (pyrazolate) or dmpz (3,5-dimethylpyrazolate); X = Cl, Br or I; PR₃= PBu₃, PMe₂Ph or PMePh₂] have been prepared. They were characterized by elemental analysis, ¹H and ³¹P NMR data and in the case of [Pd₂Cl₂(µ-dmpz)₂(PMe₂Ph)₂] by single-crystal X-ray diffraction methods. The structure determination shows two Pd atoms bridged by two dmpz ligands which form asymmetric Pd–N bond distances, an observation that may be correlated with the different trans influences associated with the Cl and P atoms which complete the square-planar geometries about the Pd atoms: monclinic, space group P2₁/c, a= 20.164(1), b= 10.140(1), c= 16.129(3)Å, β= 111.71(1)°, and Z= 4. The structure was refined to final R= 0.027 for 2906 reflections with I 2.5 σ(I).