Preparation, characterization and activity of palladium(II) halide complexes with diethyl 8-quinolylmethylphosphonate (8-dqmp). X-ray crystal structure of [8-dqmpH]2[PdCl4]·2H2O and [8-dqmpH]2[Pd2Br6]

Abstract The synthesis, spectroscopic and biological properties of the novel palladium(II) halide complexes with diethyl 8-quinolylmethylphosphonate (8-dqmp) have been reported. It was shown that the square planar complexes trans -[Pd(8-dqmp) 2 X 2 ] were obtained by reaction of 8-dqmp with PdX 4 2− (XCl, Br) in the neutral ethanolic/aqueous solution. In the HX acidic medium the quinolinium salt complexes [8-dqmp H] 2 [PdX 4 ] were isolated. They were converted by heating in methanol into the corresponding hexahalodipalladium salt complexes [8-dqmpH] 2 [Pd 2 X 6 ]. The new complexes were characterized on the basis of elemental and thermogravimetric analysis, magnetic and conductance measurements, by the IR and 1 H NMR spectra and some X-ray crystal structure determinations. The complexes were tested for their cytostatic activity on KB and L1210 cell lines. The coordination behaviour of 8-dqmp as well as the spectral and biological properties of its complexes were compared with the results reported for the diethyl ester of 2-quinolylmethylphosphonic acid (2-dqmp) and its palladium(II) halide complexes. The molecular structures of the complexes [8-dqmpH] 2 [PdCl 4 ]·2H 2 O ( 3 ) and [8-dqmpH] 2 [Pd 2 Br 6 ] ( 6 ) have been fully characterized by X-ray diffraction studies. The crystals of both complexes are triclinic, space group P 1, Z =2, with lattice parameters for 3 : a =9.438(2), b =9.481(2), c =11.082(2) A, α=83,4(1), β=107.5(1), γ=77.0(1)°, the final R factors are R =0.0481 and R ′=0.0551 for 3208 observed diffractometer collected reflections; and for 6 : a =11.943(2), b =10.644(2), c =8.873(2) A, α=102.08(2), β=85.56(2), γ=69.54(2)°, the final R factors are R =0.0725 and R ′=0.0804 for 2584 observed diffractometer collected reflections. The structure of 3 is composed of the square planar PdCl 4 2− anion lying in a centre of symmetry (average PdCl=2.330 A), of two quinotinium phosphonate cations and two water molecules. The structure of 6 consists of two quinolinium moieties as a cationic part separated by the Pd 2 Br 6 centrosymmetric dianionic dimer.