Synthesis of new platinum(II) compounds with several bidentate and tridentate nitrogen-donor ligands. Structural analyses by 1H, 13C{1H} and 195Pt{1H} NMR spectroscopy and X-ray crystal structure

The reaction of the N-alkylaminopyrazole (NN′) ligands 1-[2-(ethylamino)ethyl]-3,5-dimethylpyrazole (deae), 1-[2-(tert-butylamino)ethyl]-3,5-dimethylpyrazole (deat), or (NN′N) ligands bis[(3,5-dimethylpyrazolyl)methyl]ethylamine (bdmae) and bis[(3,5-dimethylpyrazolyl)ethyl]ethylamine (ddae) with [PtCl2(CH3CN)2] affords a series of square-planar Pt(II) complexes with formula [PtCl2(NN′)] (NN′ = deae (1); deat (2)), [PtCl2(bdmae)] (3), or [PtCl(ddae)]Cl (4). Treatment of complex 4 in the presence of AgBF4 in CH2Cl2/methanol (3:1) gives [PtCl(ddae)](BF4) (5). These Pt(II) complexes have been characterised by elemental analyses, conductivity measurements and IR, 1H, 13C{1H}, and 195Pt{1H} NMR spectroscopies. The 1H NMR spectroscopic studies of the complexes prove the rigid conformation of the ligands when they are complexed. The solid-state structure of complex 1 was determined by single crystal X-ray diffraction methods. The deae ligand is coordinated through the Npz and Namino atoms to the metallic centre, which completes its coordination with two chlorine atoms in cis disposition.