Hamdallah A. Hodali

Homo- and copolymerization of strained cyclic olefins with new palladium(II) complexes bearing ethylene-bridged heterodonor ligands

Amorphous and high molar mass polymers of norbornene and phenylnorbornene (endo/exo ratio of 80/20) were prepared by the use of new dicationic palladium(II) single-component catalysts of the general type [Pd(L∩L)(NCCH 3 ) 2 ](BF 4 ) 2 . [(L∩L) = 2-(diphenylarsino)-1-(methylthio)ethane (S∩As, 1) (4), 2-diphenylphosphino)-1-methylthio)ethane (S∩P, 2) (5), 1, 2-bis(diphenylphosphino)ethane (P∩P, 3) (6). With increasing the trans influence of the donor atom in the ligands (P>As>S) the polymerization activity of the catalysts towards polymerization of norbornene increases instantly. Both the molecular weight and the thermal behavior of the polymer can be tailored using ethene as chain transfer agent. Catalyst 4 is also active towards the alternating copolymerization of carbon monoxide and norbornene. The isolated copolymer is highly soluble in toluene, THF and chlorinated solvents. The DSC measurement of the norbornene-carbon monoxide copolymer showed a melting temperature (T m ) of 241°C (ΔH f = 47.3 J/g) and a glass transition temperature (T g ) of 161°C which is about 170°C lower compared to the homopolynorbornene (T g ≃ 330°C).

Palladium(II) complexes bearing ethylene-bridged S∩As and S∩P donor ligands: synthesis, crystal structure and reactivity towards the polymerization of norbornene

Abstract Palladium(II) complexes of the general type [Pd(L∩L)Cl2] (4–6) and their corresponding dicationic complexes [Pd(L∩L)(NCCH3)2](BF4)2 (7–9) (L∩L=[(1-(thiomethyl)-2-(diphenylarsino)ethane] (S∩As, 1) (4, 7) [1-(thiomethyl)-2-(diphenylphosphino)ethane] (S∩P, 2) (5, 8) and [1,2-bis(diphenylphosphino)ethane] (P∩P, 3) (6, 9) have been synthesized and utilized as catalysts for the polymerization reaction of bicyclo[2.2.1]hept-2-ene (norbornene). The dichloride complexes can be activated with methylaluminoxane (MAO), while the corresponding dicationic compounds were used as single component catalysts for the polymerization reactions. Catalytic performance of the new type of catalyst can be altered by modifying the donor atoms in the bidentate ligand. The activity of the Pd(II) complexes towards the polymerization reaction increases with increasing the trans-influence of the donor atoms (P∩P>S∩P>S∩As). The influence of donor atoms on the length of the PdCl bonds was elucidated by X-ray structure analysis carried out on the palladium(II) complex [Pd(S∩As)Cl2] (4).

Some dioxouranium(VI) complexes of azo-oximes

Abstract Reactions of arylazobenzaldoximes, X-(C6H4)C( NOH)N NPh(HL), where X H, p-Cl, p-CH3O, p-NO2, or arylazoformaldoximes, HC( NOH)N N(C6H4Y Y(HL), where Y p-CH3C( O) , p-Cl, p-CH3O, p-CH3, p-NO2, with UO2(OAc)2.·2H2O in methanol yielded complexes with the formula UO2(L)2·ηH2O, where η 1–5. These dioxouranium(VI) complexes were characterized by elemental analyses, conductivity measurements, IR and 1H NMR spectroscopy. In these complexes, the azo-oximes act as bidentate ligands by bonding through the oxime-oxygen and an azo-nitrogen.

Syntheses, characterization and reactions of some methyl derivatives of platinum(II). Part I.

Abstract Reactions of [Pt(COD)(CH 3 ) 2 ] (where COD = 1, 5-cyclooctadiene) with the mixed bidentate ligands, 8-(diphenylarsino)quinoline (N-As), 8-diphenylphosphino)quinoline (N-P), 1-thiomethyl)-2- (diphenylarsino)ethane (S-As) and 1-(thiomethyl)-2- (diphenylphosphino)ethane (S-P), gave a series of dimethyl platinum(II) complexes, [Pt(L-L′)(CH 3 ) 2 ] (where L-L′= N-As, N-P, S-As, S-P). Reaction of methyllithium with [Pt(L-L′)Cl 2 ] (where L-L′= S-As, S-P) and [PtL 2 Cl 2 ] (where L = diphenyl(2-phenylethyl)phosphine (PE), or diphenyl(1-naphthyl)phosphine (PN)) gave the dimethyl complexes, [Pt(L-L′)(CH 3 ) 2 ] and cis -[Pt(L) 2 (CH 3 ) 2 ], respectively. Reactions of [Pt(L-L′)(CH 3 ) 2 ] (where L-L′ = S-As, S-P) with hydrogen chloride or hydrochloric acid have been investigated. The complexes were characterized by elemental analysis, IR, 1 H NMR and 13 C NMR spectral data; trends in the 1 H NMR spectroscopic parameters are discussed.

Preparation of Silver- and Zinc-Doped Mullite-Based Ceramics Showing Anti-Bacterial Biofilm Properties

Zinc- and silver-doped mullite ceramic discs were prepared and tested as potentially resistant materials against bacterial adhesion and biofilm formation. Elemental analysis and X-ray diffraction studies showed that zinc ions were incorporated in the structural framework of the mullite, while silver ions remained outside the mullite crystal lattice, which allowed their slow (0.02 ppm/24 hours) leaching into the surrounding aqueous environment. In agreement with this behavior, silver-doped mullite showed potent resistance against surface attachment of Pseudomonas aeruginosa, while on the other hand, zinc-doped mullite failed to stop bacterial attachment.

Kinetics of oxidation of ascorbic acid by octacyanomolybdate(V) in aqueous methanol—a comparative study

Abstract The oxidation of ascorbic acid (AH2) by octacyanomolybdate(V) in a buffered acidic aqueous methanolic medium has been studied and compared with that of hexacyanoferrate(III) and octacyanotungstate(V). The reaction has been found to be first-order with respect to both oxidant concentration and ascorbic acid concentration. The dependence on acidity suggested a rate law of the form: −d[OX]/2dt = (ka+kb/[H+])[OX][AH2], where ka is the rate constant of the reaction with molecular ascorbic acid and approximately equals zero for [Fe(CN)6]3− and [W(CN)8]3− and kb is the rate constant of the reaction with the ascorbate anion. The rate measurements for the three oxidants were used to calculate the entropies and enthalpies of activation. The differences in the rates of oxidation of ascorbic acid by the three oxidants, which are in the order MoV > FeIII > Wv, are discussed.

Complexes of some mixed-donor ligands with Rh(I), Ir(I) and Ir(III)

Abstract Reactions of the mixed bidentate ligands: 8-(diphenylarsino)quinoline (N-As), 8-(diphenylphosphino)quinoline (N-P), and 8-aminoquinoline (N-N) with the rhodium dimer, [Rh(CO) 2 Cl] 2 , were investigated. The complexes [Rh(N-As)(CO)Cl], [Rh(N-P)(CO)Cl], and [Rh(N-N)(CO) 2 ]Cl have been isolated and characterized. Reactions of the above ligands with iridium anion, [Ir(CO) 2 Cl 2 ] − , gave [IrH(N-As)(CO)Cl 2 ], [Ir(N-P)(CO)Cl], and [Ir(N-N)(CO)Cl], respectively. Structures for the above complexes were assigned based on their IR and 1 H NMR spectra, analyses, electrical conductance and molecular weight measurements.

Arylamidoxime Complexes of Antimony(V)

Abstract Arylamidoximes (LH) react with SbCl5 to give adducts of the general formula SbCl5LH. Sodium arylamidoximates react with Ph3SbBr2 to give compounds of the general formula Ph3SbL2. These hexa-coordinated antimony complexes were characterized by elemental analyses, spectral data and conductivity measurements.

Substituent effects on the oxidation of benzoins by the octacyanomolybdate(V) ion

Abstract The kinetics of the oxidation of a series of benzoins (BH2) by octacyanomolybdate(V) (OX3−), in a buffered alkaline aqueous methanolic medium, have been studied spectrophotometrically. The experimental results are in agreement with the following rate law: − 1 2 d[OX3−]/dt = k[OX3−][BH2][OH−], and the following order of reactivity was observed: o,o′-dichloro- > p,p′-dichloro- > m,m′-dimethoxybenzoin > benzoin > p,p′-dimethoxy- > o,o′-dimethoxybenzoin. The rate measurements were used to calculate the thermodynamic activation parameters ΔG‡, ΔH‡ and ΔS‡. The relative rates correlate very well with the Hammett substituent constants and support a negatively-charged intermediate. The effect of substituents correlated with a p-value of 1.36.

Cyclopalladated Complexes of Arylamidoximes

Abstract Interactions of some arylamidoximes with lithium tetrachloro-palladate(II) in the presence of sodium acetate have been studied. The arylamidoximes investigated afford cyclopalladated, chlorobridged, binuclear complexes. The reaction of these complexes with triphenylphosphine is also examined. The products were identified on the basis of their elemental analysis, conductivity measurements, IR and NMR spectral data.