F. Maggio

Studies in co-ordination chemistry—VIII Magnetic, spectrophotometric and dielectric measurements on a series of Bis-(N-Alkylsalicylaldimino)-copper(II) complexes(1)

Abstract Magnetic, spectrophotometric and dielectric measurements have been made with a series of tetraco-ordinated complexes of copper(II) with N-alkylsalycylaldimines, in order to account for the orientation polarization shown by these chelates in benzene and dioxane solution. The magnetic moments of these compounds measured between 90 and 400°K lie between 1·83 and 1·90 B.M. and are essentially independent of temperature. They remain practically unchanged when the solids are dissolved in benzene. This is not to be expected if the compounds have a tetrahedral structure in solution. The high values of the difference P 2∞ − P E found for these chelates even in “non-co-ordinating” solvents like cyclohexane and carbon tetrachloride do not support the assumption that asymmetrical pentaco-ordinated adducts with a mole of solvent are formed in solution. Such results are in accord with the hypothesis already put forward by us that in solution the above complexes have a flattened pyramidal structure.

Polynuclear manganese(II) complexes with terdentate schiff bases

Die durch Kondensation von o-Aminophenol oder -thiophenol mit Salicylaldehyd oder o-Vanillin synthetisierten Liganden H21, bilden bei der stochiometrischen Umsetzung mit Mn(II)-acetatdihydrat die 1:1-Komplexe (I).

Organometallic complexes with biological molecules : IX. Diorgano- and triorgano-tin(IV)[meso-tetra(4-sulfonatophenyl)porphinate] derivatives : Solid-state and solution-phase structural aspects and in vivo effects

Diorgano- and triorgano-tin(IV) derivatives of meso-tetra(4-sulfonatophenyl)porphine (H4TPPS) with general formula (R2Sn)2TPPS and (R3Sn)4TPPS (TPPS4−=[meso-tetra(4-sulfonatophenyl)porphinate]4−, R=Me, Bu, Ph) have been obtained and their solid-state configuration inferred on the basis of IR and Mossbauer spectroscopy, while solution-phase studies have been carried out by 1H and 13C NMR in DMSO-d6, together with determination of the in vivo cytotoxicity of the new derivatives towards embryonic development of Ciona intestinalis. In particular, octahedral and trigonal-bipyramidal eq-R3Sn polymeric configurations are proposed, in the solid state, respectively for (R2Sn)2TPPS and (R3Sn)4TPPS complexes, with the arylsulfonate groups behaving as monoanionic bidentate bridging ligands. The 1H and 13C NMR data lead to the conclusion that the metal-to-ligand ratio (2:1 or 4:1), binding site (the sulfonato-group oxygens), and the coordination polyhedron around the metal (trans-octahedral or trigonal-bipyramidal) found in the solid state are preserved in solution.

Adduct formation by sub-coordinated metal complexes—IV: Studies on the coordination of cyclic nitrogen bases with bis-(salycilaldoximate)-nickel(II)

Abstract Adducts of bis-(salicylaldoximate)-nickel(II), Ni(salox)2, with pyridine, picolines, cyclomethyleneimines are reported. Their formula is Ni(salox)2L2. The compounds are characterized by magnetic and spectrophotometric measurements. Solutions of Ni(salox)2 in each base are studied similarly. The adducts are hexacoordinate in solution or in the solid state, with pseudo-octahedral or D2h symmetry. The solution of Ni(salox)2 in 2-picoline is peculiar, showing a temperature dependent equilibrium between the adduct Ni(salox)2-(2picoline)2 and the parent complex.

Organometallic complexes with biological molecules, VI. Diorganotin(IV) and triorganotin(IV) ampicillin and methicillin derivatives : Spectroscopic investigations in the solid state

Derivatives of D(-)-α-aminobenzylpenicillin (ampicillin) and of 2,6-dimethoxyphenylpenicillin (methicillin) with diorgano- and triorgano-tin(IV) moieties have been synthesized. The stoichiometries of the compounds obtained were of the type R 2 SnCIL.H 2 O, R 3 SnCILNa.H 2 O [L=ampicillin or methicillin monoanion; R=Me, Bu, Ph] and R 2 Snampic 2 . 2H 2 O (ampic=ampicillin; R=Me, Bu, Ph). For R 2 SnCIL.H 2 O and R 3 SnCILNa.-H 2 O, infrared (IR) data suggest five-coordination around the tin(IV) atom; in R 2 Snampic 2 .2H 2 O six-coordination is most likely to occur. Thermogravimetric (TG) analysis excludes any involvement in the coordination of tin(IV) by water molecules, in any of the compounds. Trigonal bipyramidal configurations in the solid state are proposed for both R 2 SnCIL.H 2 O and R 3 SnCILNa.H 2 O (L=ampicillin or methicillin) on the basis of the above-mentioned IR and Mossbauer data. As far as R 2 Snampic 2 .2H 2 O compounds are concerned, the coordination geometry at tin could be, as previously reported for analogous R 2 Snamox 2 .2H 2 O derivatives, skew-trapezoidal bipyramidal, the monoanionic bidentate chelating ampicillin residue being in the trapezoidal plane and having bent axial organic groups. Electronegativity equalization procedures have been applied to idealized trigonal bipyramidal structures for R 2 SnCIL.H 2 O and R 3 SnCILNa.H 2 O (L=ampicillin or methicillin) and to octahedral trans-R 2 for R 2 Snampic 2 .2H 2 O, to estimate the partial atomic charges on the tin atoms, Q Sn , which have been correlated with the isomer shift (6) Mossbauer parameter

Organometallic Complexes with Biological Molecules. XIV. Biological Activity of Dialkyl and Trialkyltin(IV) (Meso-tetra(4-carboxy- phenyl)porphinate) Derivatives

Molecules. XIV. Biological Activity of Dialkyl and Trialkyltin(IV) [Meso-tetra(4-carboxyphenyl)porphinate] Derivatives C. Mansueto, E. Puccia, F. Maggio, R. Di Stefano, T. Fiore, C. Pellerito, F. Triolo and L. Pellerito* Dipartimento di Biologia Animale, Universita di Palermo, Via Archirafi 18, 90123 Palermo, Italy Dipartimento di Chimica Inorganica, Universita di Palermo, Viale delle Scienze, Parco d’Orleans, 90128 Palermo, Italy

Organometallic Complexes with Biological Molecules: VIII. Synthesis, Solid State and in vivo Investigation of Triorganotin(IV) Derivatives of l-Homocysteic Acid

Several new triorganotin(IV) derivatives of L-homocysteic acid (L-HCAH) with formula R3Sn(L-HCA) (R=Me, nBu, Ph) have been synthesized. Their solid-state configurations were determined by IR and Mossbauer spectroscopy. The tin(IV) atom is five-coordinated in all the complexes, with the L-homocysteic acid behaving as a monoanionic bidentate ligand coordinating the tin(IV) atom through a chelating or bridging carboxylate group. The sulfonate (SO3−) and NH3+ groups of L-homocysteic acid maintain their free acid configuration and hence do not participate to the coordination of the tin(IV) atom. Coordination hypotheses have been checked through the correlation between the Mossbauer parameter isomer shift, δ, and partial atomic charge on the tin atoms, QSn, performed, for all the new organotin(IV) compounds, on the basis of an equalization procedure applied to idealized trigonal-bipyramidal structures for R3Sn(L-HCA). 1H and 13C NMR spectra of the complexes show that pentacoordination of the tin atom, with R groups in the equatorial plane of a trigonal bipyramid, is retained in DMSO solution. The NMR data confirm also that the uncoordinated NH3+ group of the ligand is still present in solution. Results gathered after exposure of two- to four-cell embryos of the sea urchin Paracentrotus lividus (Echinodermata) to the triorganotin(IV) L-homocysteate derivatives as well as to the parent triorganotin(IV) chlorides document cytotoxicity of the complexes, while free L-homocysteic acid exerts no significant toxic activity. The trimethyltin(IV) L-homocysteate derivative seems to exert a lower cytotoxicity than the tributyl- and triphenyl-tin(IV) ones. Different structural lesions have been identified by comparative analysis of mitotic chromosomes from untreated embryos (negative controls) and embryos treated with triorganotin(IV) L-homocysteate derivatives, such as (1) suppression of the stretch among sister chromatids at the beginning of anaphase stage; (2) deeply stained zones mainly located at the telomeric regions of chromosomes; (3) arm breakages; and (4) chromosome bridges among daughter chromosomes at anaphase stage. A colchicine-like effect of triorganotin(IV) L-homocysteate derivatives was observed.

A study of the nature and stability of the system uranyl-benzohydroxamic acid in acid medium

Abstract Spectrophotometric and conductometric measurements made in aqueous acid solutions containing UO22+ and benzohydroxamic acid (HB), show the formation of the complex ion UO2B+. The stability constant of this ion is 5·2 × 107 at 20°C and at ionic strength 1·0. The value of the stability constant shows that the complex ion is very stable at pH values between 2·3 and 2·8. The results confirm that under such experimental conditions protonic displacement from bezohydroxamic acid by the uranyl ion occurs HB + UO22+⇌UO2+H+.

Organometallic complexes with biological molecules: XII. Solid‐state and solution studies on dialkyltin(IV)– and trialkyltin(IV)–thiaminepyrophosphate derivatives

Dialkyltin(IV) and trialkyltin(IV) derivatives of the coenzyme thiaminepyrophosphate (H2TPP) have been synthesized with general formula R2Sn(HTPP)2·nH2O (Alk = Me, n = 2; Alk = Bu, n = 4) and R3SnHTPP·nH2O (R=Me, n = 2; R = Bu, n = 1), respectively. The solid-state structure of the complexes has been investigated through infrared and Mossbauer spectroscopy. The infrared data suggest the involvement of only phosphate oxygen atoms in the coordination of both dialkyl- and trialkyl-tin(IV) moieties, with phosphate anions behaving as monoanionic bidentate bridging or chelating groups, with the tin(IV) involved in six- and five-fold coordination geometries, respectively, in R2Sn(HTPP)2·nH2O (R = Me, n = 2; R = Bu, n = 4) and R3SnHTPP·nH2O (R = Me, n = 2; R = Bu, n = 1). The 119Sn Mossbauer data, and in particular rationalization of the experimental nuclear quadrupole splittings, Δ, through the point-charge model formalism, suggests the occurrence of an octahedral trans-R2 structure in R2Sn(HTPP)2·nH2O (R = Me, n = 2; R = Bu, n = 4) and a trigonal-bipyramidal structure in R3SnHTPP·nH2O (R = Me, n = 2; R = Bu, n = 1). 1H and 13C NMR spectra, in D2O, suggested that the soluble derivatives, at room temperature, in solution, maintained the solid-state structure. The interactions of dibutyltin(IV)–thiaminepyrophosphate (DBTPP) and tributyltin(IV)–thiaminepyrophosphate (TBTPP) complexes with Bluescript KS(+) plasmid and immortalized 3T3 fibroblasts were studied. Both compounds have a clear inhibitory effect on the growth of immortalized mouse embryonal fibroblasts (NIH-3T3), TBTPP being the much more active. No evidence was found, however, for DNA cleavage by the compounds at molar ratios as high as 1:10 (DBTPP, TBTPP/DNA base pairs). According to our observations, the cytotoxicity of TBTPP does not seem to be based on direct interaction with DNA, but in the presence of TBTPP (1:10, TBTPP/DNA bp), plasmid DNA seems to be more susceptible to cleavage by UV. Copyright

Trimethylplatinum(IV) complexes with ON bidentate ligands

Abstract Complexes of the trimethylplatinum(IV) moiety with bidentate monobasic salicylaldimines C 6 H 5 (OH)CHNR (R = ethyl, propyl, phenyl) have been prepared and characterized by IR, UV and NMR spectra and magnetic susceptibility measurements. The complexes are dimeric with double PtOPt bridges, and the metal appears to be pseudo-octahedrally hexacoordinated.