Synthesis and characterisation of palladium(II) and platinum(II) compounds containing pyrazole-derived ligands: crystal structure of [PdCl 2(HL 1)] (HL 1 = 3-phenyl-5-(2-pyridyl)pyrazole)

Abstract

Reaction of the ligands 3-phenyl-5-(2-pyridyl)pyrazole ( HL 1 ), 3,5-bis(2-pyridyl)pyrazole ( HL 2 ), 3-methyl-5-(2-pyridyl)pyrazole ( HL 3 ) and 3-methyl-5-phenylpyrazole ( HL 4 ) with [MCl 2(CH 3CN) 2] (M = Pd(II), Pt(II)) or [PdCl 2(cod)] gives complexes with stoichiometry [PdCl 2(HL) 2] (HL = HL 1, HL 2, HL 3), [Pt(L) 2] (L = L 1, L 2, L 3) and [MCl 2(HL 4) 2] (M = Pd(II), Pt(II)). The new complexes were characterised by elemental analyses, conductivity measurements, infrared and 1H NMR spectroscopies. The crystal and molecular structure of [PdCl 2(HL 1)] was resolved by X-ray diffraction, and consists of monomeric cis-[PdCl 2(HL 1)] molecules. The palladium centre has a typical square planar geometry, with a slight tetrahedral distortion. The tetra-coordinated metal atom is bonded to one pyridine nitrogen, one pyrazolic nitrogen and two chloro ligands in a cis disposition. The ligand HL 1 is not completely planar.