William M. Motswainyana

Imino-phosphine palladium(II) and platinum(II) complexes: Synthesis, molecular structures and evaluation as antitumor agents

The imino-phosphine ligands L1 and L2 were prepared via condensation reaction of 2-(diphenylphosphino)benzaldehyde with substituted anilines and obtained in very good yields. An equimolar reaction of L1 and L2 with either PdCl2(cod) or PtCl2(cod) gave new palladium(II) and platinum(II) complexes 1-4. The compounds were characterized by elemental analysis, IR, (1)H and (31)P NMR spectroscopy. The molecular structures of 2, 3 and 4 were confirmed by X-ray crystallography. All the three molecular structures crystallized in monoclinic C2/c space system. The coordination geometry around the palladium and platinum atoms in respective structures exhibited distorted square planar geometry at the metal centers. The complexes were evaluated in vitro for their cytotoxic activity against human breast (MCF-7) and human colon (HT-29) cancer cells, and they exhibited growth inhibitory activities and selectivity that were superior to the standard compound cisplatin.

Antitumor activity of phenylene bridged binuclear bis(imino-quinolyl)palladium(II) and platinum(II) complexes.

Antitumor effects of a known bis(imino-quinolyl)palladium(II) complex 1 and its newly synthesized platinum(II) analogue 2 were evaluated against human breast (MCF-7) and human colon (HT-29) cancer cell lines. The complexes gave cytotoxicity profiles that were better than the reference drug cisplatin. The highest cytotoxic activities were pronounced in complex 2 across the two examined cancer cell lines. Both compounds represent potential active drugs based on bimetallic complexes.

Dichlorido[2-(phenyl­imino­meth­yl)quinoline-N,N′]palladium(II)

In the title complex, [PdCl2(C16H12N2)], the PdII ion is coordinated by two N atoms [Pd—N 2.039 (2), 2.073 (2) Å] from a bidentate ligand and two chloride anions [Pd—Cl 2.2655 (7), 2.2991 (7) Å] in a distorted square-planar geometry. In the crystal, π–π interactions between the six-membered rings of the quinoline fragments [centroid–centroid distances = 3.815 (5), 3.824 (5) Å] link two molecules into centrosymmetric dimers.

Hemilabile imino-phosphine palladium(II) complexes: synthesis, molecular structure, and evaluation in Heck reactions

The ligands 2-(diphenylphosphino)benzyl-(2-thiophene)methylimine (V) and 2-(diphenylphosphino) benzyl-(2-thiophene)ethylimine (VI) were prepared from 2-(diphenylphosphino)benzaldehyde and thiophene amines with very good yields. An equimolar reaction of V and VI with either PdCl2(cod) (cod = cyclooctadiene) or PdClMe(cod) afforded palladium(II) complexes I–IV. The molecular structure of II was confirmed by X-ray crystallography. The coordination geometry around the palladium atom exhibited distorted square planar geometry at the palladium centre. Complexes I, II, and IV were evaluated as catalysts for Heck coupling reactions of iodobenzene with methyl acrylate under mild reaction conditions; 0.1 mole % catalyst, Et3N base, MeCN reflux for 8 h, 80°C; isolated yield on a 10 mmol scale with catalyst I (64 %), II (68 %), and IV (58 %). They all exhibited significant activities.

Dichlorido{N-[(5-methyl­thio­phen-2-yl)methyl­idene]-2-(pyridin-2-yl)ethanamine-κ2N,N′}palladium(II)

In the title compound, [PdCl2(C13H14N2S)], the PdII ion is coordinated by two N atoms of the chelating bidentate ligand and two chloride anions, giving rise to a distorted square-planar geometry. The methyl-substituted thiophene arm and the pyridine ring are connected to the metal cation through N atoms to form a six-membered chelate ring with a boat conformation, making the complex stable.

Chlorido[2-({[2-(diphenyl­phosphan­yl)­benzyl­idene]amino}­meth­yl)thio­phene-κ2N,P]methyl­palladium(II)

In the title compound, [Pd(CH3)Cl(C24H20NPS)], the PdII ion is coordinated in a distorted square-planar environment which includes the P and N atoms of the bis-chelating ligand. The thiophene ring is rotationally ordered, unlike in the majority of crystal structures containing this group.

Quinoline-2-carbaldehyde

The title compound, C10H7NO, crystallizes with two almost planar molecules (A and B) in the asymmetric unit (r.m.s. deviations = 0.018 and 0.020 Å). In the crystal, the A molecules are linked by weak C—H⋯O interactions, thereby generating C(9) [001] chains. The B molecules do not exhibit any directional bonding interactions.

Dichlorido{2-[(thio-phen-2-ylmeth-yl)imino-meth-yl]pyridine-κN,N'}palladium(II).

In the title compound, [PdCl2(C11H10N2S)], the PdII ion is four-coordinated in a distorted square-planar environment by two N atoms of the chelating 2-[(thiophen-2-ylmethyl)iminomethyl]pyridine ligand and two chloride anions. The thiophene ring is rotationally disordered over two orientations in a 1:1 ratio. The crystal packing exhibits weak intermolecular C—H⋯Cl and C—H⋯S hydrogen bonds.

Chlorido{N-[2-(diphenylphosphanyl)benz­ylidene]-2-(2-thienyl)ethanamine-κ2N,P}methylpalladium(II) dichloromethane hemisolvate

In the title compound, [Pd(CH3)Cl(C25H22NPS)]·0.5C2H2Cl2, the PdII atom is coordinated by the N,P-bidentate ligand, a methyl group and a chloride ion, generating a distorted square-planar PdCClNS coordination geometry, with the N and Cl atoms trans. The thiophene ring is equally disordered over two orientations and the dichloromethane solvent molecule is disordered about an inversion centre.

Dichlorido{N-[2-(diphenylphosphanyl)benzylidene]-2-methylaniline}palladium(II) acetonitrile monosolvate

The title imino-phosphine compound, [PdCl2(C26H22NP)]·CH3CN, was prepared by reaction of N-[2-(diphenylphosphanyl)benzylidene]-2-methylaniline with dichlorido(cycloocta-1,5-diene)palladium(II) in dry CH2Cl2. The Pd(II) cation is coordinated by the P and N atoms of the bidentate chelating ligand and by two chloride anions, generating a distorted square-planar coordination geometry. There is a detectable trans influence for the chloride ligands. The methyl group present in this structure has an influence on the crystal packing.