Organophosphines in PtP2Si2 derivatives – structural aspects

Abstract

In this review, the structural data of monomeric platinum(II) complexes with inner coordination spheres of Pt(η²-P₂L)(SiL)₂, Pt(η²-P₂L)(η²-Si₂L) and Pt(η²-P,SiL)₂ are classified and analyzed. These complexes crystallize in three crystal systems: monoclinic (8 examples), triclinic (4 examples) and orthorhombic (4 examples). Distorted square-planar environments about the Pt(II) atoms are built up by combination of homobi-P,P with two monodentate Si donor ligands; homobi-PP with homo-Si,Si donor ligands, or heterobi-P,Si donor ligands. The chelating ligands create metallacycles with the following angles: 65.0° (SiOSi) < 83.1° (SiC₂Si) < 85.2° (PC₂P) < 88.8° (SiSi₂Si)). The mean Pt-P and Pt-Si bond distances in Pt(η²-P₂L)·(SiL)₂ complexes are 2.319 and 2.365?Å; in Pt(η²-P₂L)(η²-Si₂L) the values are 2.316 and 2.360?Å. The complex [Pt{η²-Me₂P(C₂B₁₀H₁₀)SiMe₂}₂] exists in two isomeric forms, a monoclinic cis- and a triclinic trans-isomer. The structural data are compared and discussed with the complexes of inner coordination spheres: Pt(η²-P₂L)(XL)₂ (X?=?O, N, CN, BL, Cl, SL, SeL, Br, or I) and Pt(η²-P₂L)(η²-X₂L) (X?=?OL, NL, SL or SeL).     

A Cyclic and Polymeric Phosphazene as Solid State Template for the Formation of RuO<Subscript>2</Subscript> Nanoparticles

Pyrolysis of the organometallic polymer: {{[N=P(R₁)]_0.8[N=P(OC₆H₄CH₂CN[Ru])₂]_0.15[N=P((OC₆H₅)(OC₆H₄CH₂CN[Ru]]_0.05}{Cl}_0.31} _n , [Ru]=CpRu(PPh₃)₂, R₁ = O₂C₁₂H₈ (1) as well of the cyclic specie {N₃P₃ (OC₆H₅)₅(OC₆H₄CH₂CN[Ru])}{PF₆} (2) under a flow of air at 800°C affords nanostructured RuO₂. Nanoparticles near to 10 nm were observed. The differences in the use of cyclic or polymeric phosphazenes, as solid state template, influence strongly the morphology and slightly the composition of the pyrolytic product. Temperature variable (SQUID) measurements in the range of 5–300 K of the material obtained from the polymer, indicate an antiferromagnetic interaction between the Ru atoms, although lower than that found for the crystalline ruthenium oxide, probably due to some amorphous product present in the pyrolytic material. The possible formation mechanism is discussed and the differences in using the cyclic or the polymeric compound as precursor is analyzed in terms of the relative content of Ru to P, N. A general formation method of nanostructured metal oxides is proposed.     

Analysis of endosulfan and its metabolites in human serum using gas chromatography-tandem mass spectrometry

A new analytical method combining solid-phase extraction and gas chromatography-tandem mass spectrometry (GC-MS-MS) is proposed to determine the insecticide endosulfan as well as its metabolites endosulfan-ether, -lactone, and -sulfate in human serum. Most matrix interferences are avoided using a cleanup step included in the sample treatment and an instrumental technique such as GC-MS-MS, which presents a high sensitivity and selectivity. Recoveries of spiked compounds range between 94.8 and 100.4% and 93.4 and 99.7% at fortification levels of 10 and 30 ng/mL, respectively. The relative standard deviation is lower than 17.6% in all cases, and the limits of detection calculated range from 6 to 19 pg/mL. Serum samples of nine agricultural workers that spray endosulfan into greenhouses in Almería (Spain) and two nonoccupationally exposed people are analyzed, and endosulfan is found in all the samples studied.     

Template-assisted self assembly of two lipophilic polyion aggregates derived from sodium tetraphenyl imidodiphosphinate-complexes containing sodium ions in four different coordination environments

The molecular structures of two lipophilic polyion aggregates derived from tetraphenyl imidodiphosphinate are described: [Na(crown ether)][MNa(2)[Ph(2)P(O)NP(O)Ph(2)](4)] with crown ether = 15-crown-5 for 1and benzo-15-crown-5 for (M = Na(+) for 1 and Na(H(2)O)(+) for 2).     

Glycosylation site analysis of human alpha-1-acid glycoprotein (AGP) by capillary liquid chromatography-electrospray mass spectrometry

A new anionic surfactant (RapiGest SF) was successfully used for site-specific analysis of glycosylation in human alpha-1-acid glycoprotein (AGP). By means of this analytical approach combined with capillary HPLC-mass spectrometry (and tandem mass spectrometry), the N-linked glycosylation pattern of AGP was explored. On the basis of mass matching and MS/MS experiments ca 80 different AGP-derived glycopeptides were identified. Glycosylation shows a markedly different pattern for the various glycosylation sites. At sites I and II, triantennary complex-type oligosaccharides predominate and at sites III, IV and V, tetra-antennary complex-type oligosaccharides predominate. Sites IV and V show the presence of additional N-acetyl lactosamine (Gal-GlcNAc) units (even higher degree of branching and/or longer antennae are also present).     

Bis(2,4,6-trifluorophenyl) derivatives of palladium(II)

Summary The organopalladium(II) complexes: Pd(2,4,6-C₆F₃H₂)₂L₂ [L=triphenylphosphine(PPh₃), methyldiphenylphosphine(PPh₂Me), dimethylphenylphosphine-(PPhMe₂) or pyridine(py); L₂=1,2-bis(diphenylphosphino)ethane(dpe), 2,2-bipyridine(bipy), 1, 10-phenanthroline(phen) or ethylenediamine(en)] have been prepared by addition of the appropriate compound to the THF-dioxane solution resulting from the arylation of potassium tetrachloropalladate(II) with (2,4,6-C₆F₃H₂)MgBr. The i.r. data suggest that the py and PPhMe₂ compounds are thecis-isomers, whereas the PPh₃ and PPh₂Me compounds have thetrans configuration.¹H- and¹⁹F-n.m.r. data for the compounds are reported.     

The direct detection of a hydrogen bond in the solid state by NMR through the observation of a hydrogen-bond mediated (15)N [bond] (15)N J coupling

A new method for detecting hydrogen bonds in the solid state is presented. Using two-dimensional NMR correlation experiments, it is shown that a hydrogen-bond mediated J coupling can be observed in a powder under magic-angle spinning conditions, even though the J coupling is 2 orders of magnitude smaller than the dominant anisotropic interactions encountered in solid-state NMR. Specifically, the observation of a pair of peaks in a two-dimensional 15N-15N solid-state INADEQUATE experiment due to two nitrogens that have no covalent connectivity is attributed to the presence of a J coupling across a linking hydrogen bond.     

Prediction of the behaviour of organic pollutants using cloud point extraction

A preconcentration study based on the cloud point phenomenon was carried out for a set of triazine herbicides, three of them chloro-substituted and three of them methylthio-substituted. Concentration factors and recoveries were calculated as function of the percentage of the non-ionic surfactant Triton X-114 employed. From these values, obtained from a cloud point extraction (CPE) procedure, the distribution coefficient between the Triton X-114 micelles and water, Kc, prior to CPE was calculated for each triazine and related to the corresponding octanol-water partition coefficient, Kow. In order to confirm the results obtained with the triazine herbicides, two sets of data from chemically different organic pollutants--organophosporous and chlorophenols--obtained from the literature were assessed, concluding that they display a similar behaviour to that of the triazine herbicides. This can be used to predict the CPE behaviour of other organic pollutants from their octanol-water partition coefficients. The Kc values were compared with the analyte concentration ratio in the surfactant-rich phase and aqueous phase (Ksa) with a view to obtaining a link between the analyte behaviour prior to and after cloud point extraction procedures.     

Global optimization of ionic Mg(n)F(2n) (n=1-30) clusters

The global optimization basin-hopping (BH) method has been used to locate the global minima (GM) of Mg(n)F(2n) (n=1-30) clusters using a Born-Mayer-type potential. Some of the GM were particularly difficult to find, requiring more than 1.5 x 10(4) BH steps. We have found that both the binding energy per MgF2 unit and the effective volume of the GM isomers increase almost linearly with n, and that cluster symmetry decreases with cluster size. The data derived from the BH runs reveal a growing density of local minima just above the GM as n increases. Despite this, the attraction basin around each GM is relatively large, since after all their atomic coordinates are randomly displaced by values as high as 2.0 bohrs, the perturbed structures, upon reoptimization, relax back to the GM in more than 50% of the cases (except for n=10 and 11). The relative stabilities derived from energy second differences suggest that n=8,10,13,15, and 20 are probably the magic numbers for these systems. Mass spectrum experiments would be very useful to clarify this issue.