Giancarlo Pelizzi

Structural studies on isoxazole derivatives: The crystal and molecular structures of Tetra(3-amino-5-methylisoxazole)bis(isothiocyanate)-nickel(II) and Tetra(3-amino-5-methylisoxazole)bromocopper(II) bromide

SummaryThe structures of the title compounds were both solved from diffractometer data by direct methods and refined by full-matrix least-squares toR=4.63% for 3069 independent reflections for the nickel compound [triclinic,a=10.499(7),b=13.295(8),c=10.182(7) Å, α=92.13(8), β=103.58(7), γ=68.79(7)°;Z=2. Space group P1] and toR=7.98% for 772 independent reflections for the copper compound [tetragonal,a=12.939(6),c=14.991(7) Å;Z=4. Space group P4/ncc]. In the first compound two chemically equivalent, crystallographically independent molecules are present, in which each nickel atom attains an octahedral coordination involving four N(ring)-bonded isoxazole molecules and two isothiocyanate groups. In the copper compound, the metal atom shows square-pyramidal fivecoordination with the four symmetry-related organic molecules bondedvia N(ring) in the square plane and one bromide ion (the other is not coordinated) in the apical position.

Antimicrobial and mutagenic activity of some carbono- and thiocarbonohydrazone ligands and their copper(II), iron(II) and zinc(II) complexes

Several mono- and bis- carbono- and thiocarbonohydrazone ligands have been synthesised and characterised; the X-ray diffraction analysis of bis(phenyl 2-pyridyl ketone) thiocarbonohydrazone is reported. The coordinating properties of the ligands have been studied towards Cu(II), Fe(II), and Zn(II) salts. The ligands and the metal complexes were tested in vitro against Gram positive and Gram negative bacteria, yeasts and moulds. In general, the bisthiocarbonohydrazones possess the best antimicrobial properties and Gram positive bacteria are the most sensitive microorganisms. Bis(ethyl 2-pyridyl ketone) thiocarbonohydrazone, bis(butyl 2-pyridyl ketone)thiocarbonohydrazone and Cu(H2nft)Cl2 (H2nft, bis(5-nitrofuraldehyde)thiocarbonohydrazone) reveal a strong activity with minimum inhibitory concentrations of 0.7 microgram ml-1 against Bacillus subtilis and of 3 micrograms ml-1 against Staphylococcus aureus. Cu(II) complexes are more effective than Fe(II) and Zn(II) ones. All bisthiocarbono- and carbonohydrazones are devoid of mutagenic properties, with the exception of the compounds derived from 5-nitrofuraldehyde. On the contrary a weak mutagenicity, that disappears in the copper complexes, is exhibited by monosubstituted thiocarbonohydrazones.

Alkynyl phenyl selenides as convenient precursors for the synthesis of stereodefined trisubstituted alkenes

Abstract The addition of p-toluensulfonic acid to alkynyl phenyl selenides is regio- and stereospecific and affords (Z)-α-(phenylseleno)vinyl p-toluensulfonates in good yield. α-(Phenylseleno)vinyl halides are obtained from the reactions of these compounds with magnesium halides. The reactions of (Z)-α-(phenylseleno)vinyl p-toluensulfonates with cyanocuprates afford the corresponding trisubstituted alkenes in which the tosyl group has been selectively substituted by an aryl or an alkyl group with retention of configuration. Finally, the cross coupling reaction of these vinyl selenides with methylmagnesium bromide, in the presence of a nickel catalyst, occurs with retention of configuration and affords the selenium free trisubstituted alkenes.

ORGANOTIN COMPLEXES WITH PYRROLE-2,5-DICARBOXALDEHYDE BIS(ACYLHYDRAZONES).SYNTHESIS, STRUCTURE, ANTIMICROBIAL ACTIVITY AND GENOTOXICITY

Mono- and bimetallic organotin complexes with pyrrole-2,5-dicarboxaldehyde bis(2-hydroxybenzoylhydrazone) (H5dfps) and pyrrole-2,5-dicarboxaldehyde bis(2-picolinoylhydrazone) (H3dfpp) were synthesized and characterized by IR, 1H and 119Sn NMR spectroscopy. X-ray analysis of the complex [Sn(H3dfps)(C6H5)2].(CH3)2SO revealed a pentacoordination around tin through a N,N,O terdentate ligand behaviour of the hydrazone. This complex is the most active compound, exhibiting MIC values of 3 and 12 micrograms/ml against Gram positive and Gram negative bacteria, respectively. None of the ligands or complexes produced DNA-damage in the Bacillus subtilis rec-assay or showed mutagenic activity in the Salmonella-microsome test.

Palladium(II) complexes containing a P, N chelating ligand Part II. Synthesis and characterisation of complexes with different hydrazinic ligands. Catalytic activity in the hydrogenation of double and triple C-C bonds

Abstract Palladium(II) complexes of the type Pd(PNO)Y (PNO = 2-(diphenylphosphino)benzaldehyde picolinhydrazone, nicotinhydrazone, isonicotinhydrazone; Y = CH3CO2, Cl, I) and Pd(PNS)Y (PNS = 2-(diphenylphosphino)benzaldehyde thiosemicarbazone; Y = CH3CO2, Cl, I) were synthesised and characterised by spectroscopic methods. The X-ray structure of an iodo complex was also determined. The catalytic activity of all the complexes in the homogeneous hydrogenation of terminal double and triple bonds was tested with particular regards to the chemoselectivity from triple to double bond. A correlation between the catalytic activity and the nature of the ligand and Y group was established. In the hydrogenation of phenylacetylene using acetato complexes as catalysts, stable phenylethynylpalladium(II) complexes were recovered and characterised by spectroscopic methods. A facile route of synthesis of alkynyl complexes was also determined.

The different behaviour of the di-2-pyridylketone 2-thenoylhydrazone in two organotin compounds. Synthesis, X-ray structure and biological activity☆

Two organotin compounds [SnPh(dpt)Cl2](1) and [SnPh3Cl(OH2)]·Hdpt (2) (Hdpt = di-2-pyridylketone 2-thenoylhydrazone) have been synthesized and characterized by IR spectroscopy and X-ray diffraction. Hdpt behaves differently in the two compounds: it is deprotonated and ONN tridentate in 1 and uncoordinated in 2, where pairs of hydrogen-bonded [SnPh3Cl(OH2)] and Hdpt molecules are present. The tin environment is octahedral in 1 and trigonal bipyramidal in 2. Compound 2 has shown good antimicrobial activity against Gram-positive bacteria and moulds in vitro. Neither compound showed genotoxic properties.

Structural researches on organotin(iv) compounds. synthesis and structure of nitratotriphenyl(triphenylphosphine oxide)tin(iv)

Abstract A nitrato-complex of organotin(IV) containing triphenylphosphine oxide, Sn(C 6 H 5 ) 3 (NO 3 ) [(C 6 H 5 ) 3 PO], has been synthesized and characterized by infrared spectroscopy and X-ray structural analysis. The compound crystallizes in space group P 1¯, with a = 11.817(6), b = 11.086(6), c = 12.471(6), α = 99.6(1),β = 90.8(1), γ = 97.8(1), Z = 2. The structure has been solved from X-ray diffractometer data by Patterson and Fourier methods and refined by least-squares calculations to R = 6.4% for 4301 independent reflections. The structure consists of discrete monomer units in which tin shows trigonal bipyramidal geometry.

Synthesis, structure and characterization of novel Cd(II) and Zn(II) complexes with the condensation product of 2-formylpyridine and selenosemicarbazide Antiproliferative activity of the synthesized complexes and related selenosemicarbazone complexes.

Two novel Cd(II) and Zn(II) complexes with the condensation product of 2-formylpyridine and selenosemicarbazide were synthesized. The structure of Cd(II) complex was determined by X-ray crystallography. The ligand is coordinated in a neutral form via pyridine and azomethine nitrogen atoms and the selenium donor. The cadmium ion completes its five-coordination by two chloride ligands, forming a square-pyramidal geometry. The structure of Zn(II) complex was established by analysis of spectroscopic data, which indicated coordination of the ligand as a bidentate via the selenium and the azomethine nitrogen atoms. The cytotoxic activity of the newly synthesized complexes, as well as if five structurally related complexes and the ligand evaluated against eight tumor cell lines. The new Cd(II) complex showed the highest activity similar to cisplatin with IC50 less than 10muM for all cell lines. Cell cycle distribution and apoptosis study showed that Cd(II) complex and cisplatin might have some similarity in anticancer activity, which was not the case for cisplatin and other studied complexes. Effects of the complexes on matrix metalloproteinases (MMPs) MMP-9 and MMP-2 was also studied. Cd(II) and Zn(II) complexes and cisplatin increased MMP-2 activity in supernatants of tested cells, while Ni(II) complex with the same ligand decreased the activity, implying a possible activity in preventing tumor invasion and metastasis processes.

Synthesis and characterization of organotin hexacyanoferrates

Abstract The synthesis and structural characterization by IR, ESR, 119 Sn and 57 Fe Mossbauer spectroscopy, X-ray powder diffraction, and TG and DSC methods of a new series of organotin hexacyanoferrates are reported.

Syntheses, characterization and X-ray structure of palladium(II) and nickel(II) complexes of tetradentate pyrrole containing ligands

Abstract Palladium(II) and nickel(II) complexes with tetradentate ligands derived from pyrrole 2-carboxaldehyde and various diamines have been synthesized and characterized. The complexes are neutral and the coordination around the metal is square-planar; they are able to activate the molecular hydrogen and to catalyse the homogenous hydrogenation of phenylacetylene. The X-ray structures of N,N′-cycloexylenebis(pyrrol-2-ylmethyleneamine) (H2L4), PdL4 and PdL3 (H2L3, N,N′-propylenebis(pyrrol-2-ylmethyleneamine)) are discussed.