Synthesis of new palladium(II) complexes containing tetradentate-nitrogen donor ligands: Combined structural studies by NMR spectroscopy and X-ray crystallography

Abstract

Treatment of the tetradentate ( NN′ N′ N) N-alkylaminopyrazole ligands 3,6-dimethyl-1,8-(3,5-dimethyl-1-pyrazolyl)-3,6-diazaoctane (ddad) and 1,4-bis[2-(3,5-dimethyl-1-pyrazolyl)ethyl]piperazine (bedp) with [PdCl 2(CH 3CN) 2] in a 1:1 M/L ratio in acetonitrile produces [Pd 2Cl 4(L)] and [PdCl 2(L)] (L = ddad and bedp). Treatment of the corresponding complex [PdCl 2(L)] (L = ddad, bedp) in the presence of AgBF 4 in CH 2Cl 2/methanol (2:1) or NaBF 4 in acetonitrile gives [Pd(L)](BF 4) 2. The Pd(II) complexes have been characterised by elemental analyses, conductivity measurements, IR and 1H and 13C{ 1H} NMR spectroscopies when possible. The X-ray structure of the complex [Pd(ddad)]Cl 2 · 3H 2O has been determined. The Pd(II) is coordinated to the ddad ligand by two nitrogen atoms of pyrazolyl groups and two nitrogen atoms of the amine groups, in a slightly distorted square-planar geometry.