Synthesis of new palladium(II) compounds with several bidentate nitrogen-donor ligands: Structural analyses by H and C{H} NMR spectroscopy and crystal structures

The reaction of PdCl₂(CH₃CN)₂] with N-alkylaminopyrazole (NN′) ligands, 1-2-(ethylamino)ethyl]-3,5-dimethylpyrazole (deae), 1-2-(ⁱpropylamino)ethyl]-3,5-dimethylpyrazole (deai), and 1-2-(^tbutylamino)ethyl]-3,5-dimethylpyrazole (deat), affords a series of square planar Pd(II) complexes PdCl₂(NN′)] (NN′ = deae (1), deai (2) and deat (3)). The solid-state structures of complexes 1 and 3 were determined by single crystal X-ray diffraction studies. The NN′ ligands are coordinated through the N_pz and N_amine atoms to the metal atom, which completes its coordination with two chlorine atoms in a cis disposition. These palladium(II) compounds were characterised by elemental analyses, conductivity measurements, IR, ¹H and ¹³C{¹H} NMR spectroscopies. The NMR studies of the complexes prove the rigid conformation of the ligands when they are complexed.