Serendipitous Formation of a Cerium(IV)-Mercury(II) Separated Ion Coordination Polymer#

Trivalent cerium tris-tert-butoxide, "[Ce(OtBu)(3)]", was synthesised in situ and treated with excess HgCl2. After reaction, colourless crystals were identified amongst excess HgCl2. Analysis by X-ray crystallography revealed the formation of an unusual ion separated coordination polymer consisting of two [Ce-IV(OtBu)(3)(thf)(3)](+) ions and a di-anionic chloridomercurate(II) two dimensional sheet [Hg8Cl18](2-), giving the overall formula [{Ce(OtBu)(3)(thf)(3)}(2){Hg8Cl18}](infinity) (1)

Unexpected C-F activation during redox transmetallation with silver N,N '-bis(2,6-difluorophenyl)formamidinate

The trivalent lanthanoid formamidinates, [Yb-2(DFForm)(4)F-2(py)(2)]center dot CH3CN (1) (DFForm=N,N'-bis(2,6-difluorophenyl)formamidinate), and [La-6(DFForm)(8)F8O(CH3CN)(2)].6CH(3)CN (2) have been prepared from redox transmetallation (RT) reactions employing lanthanoid metals and silver formamidinate (AgDFForm) in CH3CN. C-F activation was observed in both reactions. The structure of 1 is a fluorine bridged dimer with two seven-coordinate ytterbium metal ions. Surprisingly the lanthanum complex is a trivalent cage with an unexpected central oxygen atom. [La-6(DFForm)(8)F8O(CH3CN)(2)].6CH(3)CN (2) formed a 15 membered ring cage of six La atoms, eight F and one O at the centre. There are three different La3+ ions in 2 with two different coordination numbers. All the La atoms are coordinated by four bridging fluorides and the central oxygen

Superlattice Magnetophonon Resonances in Strongly Coupled InAs/GaSb Superlattices

We report an experimental study of miniband magnetoconduction in semiconducting InAs/GaSb superlattices. For samples with miniband widths below the longitudinal optical phonon energy we identify a new superlattice magnetophonon resonance (SLMPR) caused by resonant scattering of electrons across the mini-Brillouin zone. This new resonant feature arises directly from the drift velocity characteristics of the superlattice dispersion and total magnetic quantisation of the superlattice Landau level minibands.Comment: 9 pages, 8 figures, submitted to Phys. Rev.

Reinvestigation of Reactions of HgPh<inf>2</inf> with Eu and Yb Metal and the Synthesis of a Europium(II) Bis(tetraphenylborate) †

Europium bis(tetraphenylborate) [Eu(thf)7][BPh4]2⋅thf containing a fully solvated [Eu(thf)7]2+ cation, was synthesized by protolysis of “EuPh2” (from Eu and HgPh2) with Et3NHBPh4, and the structure was determined by single-crystal X-ray diffraction. Efforts to characterize the putative “Ph2Ln” (Ln = Eu, Yb) reagents led to the synthesis of a mixed-valence complex, [(thf)3YbII(μ-Ph)3YbIII(Ph)2(thf)]⋅2thf, resulting from the reaction of Yb metal with HgPh2 at a low temperature. This mixed-valence YbII/YbIII compound was studied by 171Yb-NMR spectroscopy and single-crystal X-ray diffraction, and the oxidation states of the Yb atoms were assigned

An Investigation of the Acceptor Properties of Some Organomercurials by Molecular Weight Measurements and X-ray Photoelectron Spectroscopy

Stability constants from molecular weigth measurements for the complexes R2Hgbpy (bpy = 2,2\u27-bipyridyl) in carbon tetrachloride and benzene at 25 °C decrease in the order R = CaF5 > > p-HC6F4 = p-MeOC6F4 2\u27: o-HC5F4, and for R2HgOPPha, in the order R = o-HC6F4 > C5F5 > p-HC5F4 = p-MeOC5F4 with higher values in the former solvent. The unexpectedly greater stability of (o-HC5F4)2HgOPPha than (C5F5)2HgOPPha has been related to the structures of the parent mercurials. X-ray photoelectron spectroscopy shows that the acceptor properties of mercury compounds decrease in the order HgCl2 > (C5F5)2Hg = (p-HC5F4)2Hg = (o- HC0F4)2Hg > (p-MeOCoF4)2Hg > (C5Cls)2Hg 2\u27: Ph2Hg > Hg0• A similar study of RHgX compounds suggests that there is reasonable additivity of the electrophilic effects of different R and X groups on the mercury 4f binding energy

Bromobenzene Transforms Lanthanoid Pseudo-Grignard Chemistry

Divalent lanthanoid pseudo-Grignard reagents PhLnBr (Ln=Sm, Eu and Yb) can be easily prepared by the oxidative addition of bromobenzene (PhBr) to lanthanoid metals in tetrahydrofuran (THF). PhLnBr reacts with bulky N,N′-bis(2,6-di-isopropylphenyl)formamidine (DippFormH) to generate LnII complexes, namely [Ln(DippForm)Br(thf)3]2⋅6thf (1; Sm, 2; Eu), and [Yb(DippForm)Br(thf)2]2⋅2thf (3; Yb). Samarium and europium (in 1 and 2) are seven coordinate, whereas ytterbium (in 3) is six coordinate, and all are bromine-bridged dimers. When PhLnBr reacts with 3,5-diphenylpyrazole (Ph2pzH), both divalent (5; [Eu(Ph2pz)2(thf)4]) and trivalent (4 a; [Sm(Ph2pz)3(thf)3]⋅3thf, 4 b; [Sm(Ph2pz)3(dme)2]⋅dme) complexes are obtained. In the monomeric compounds 4(a,b), samarium is nine coordinate but europium is eight coordinate in 5. The use of PhLnBr in this work transforms the outcomes from earlier reactions of PhLnI

Syntheses, Structures, and Corrosion Inhibition of Various Alkali Metal Carboxylate Complexes

Complexes of the alkali metals Li-Cs with 3-thiophenecarboxylate (3tpc), 2-methyl-3-furoate (2m3fur), 3-furoate (3fur), 4-hydroxycinnamate (4hocin), and 4-hydroxybenzoate (4hob) ions were prepared via neutralisation reactions, and the structures of [Li2(3tpc)2]n (1Li); [K2(3tpc)2]n (1K); [Rb(3tpc)(H2O)]n (1Rb); [Cs{H(3tpc)2}]n (1Cs); [Li2(2m3fur)2(H2O)3] (2Li); [K2(2m3fur)2(H2O)]n (2K); [Li(3fur)]n(3Li); [K(4hocin](H2O)3]n (4K); [Rb{H(4hocin)2}]n.nH2O (4Rb); [Cs(4hocin)(H2O)]n (4Cs); [Li(4hob)]n (5Li); [K(4hob)(H2O)3]n (5K); [Rb(4hob)(H2O)]n (5Rb); and [Cs(4hob)(H2O)]n (5Cs) were determined via X-ray crystallography. Bulk products were also characterised via XPD, IR, and TGA measurements. No sodium derivatives could be obtained as crystallographically suitable single crystals. All were obtained as coordination polymers with a wide variety of carboxylate-binding modes, except for dinuclear 2Li. Under conditions that normally gave coordinated carboxylate ions, the ligation of hydrogen dicarboxylate ions was observed in 1Cs and 4Rb, with short H-bonds and short O…O distances associated with the acidic hydrogen. The alkali-metal carboxylates showed corrosion inhibitor properties inferior to those of the corresponding rare-earth carboxylates

Oxidation of the Platinum (II) Anticancer Agent [Pt{(p-BrC6F4)NCH2CH2NEt2}Cl(py)] to Platinum (IV) Complexes by Hydrogen Peroxide

PtIV coordination complexes are of interest as prodrugs of PtII anticancer agents, as they can avoid deactivation pathways owing to their inert nature. Here, we report the oxidation of the antitumor agent [PtII(p-BrC6F4)NCH2CH2NEt2}Cl(py)], 1 (py = pyridine) to dihydroxidoplatinum(IV) solvate complexes [PtIV{(p-BrC6F4)NCH2CH2NEt2}Cl(OH)2(py)].H2O, 2·H2O with hydrogen peroxide (H2O2) at room temperature. To optimize the yield, 1 was oxidized in the presence of added lithium chloride with H2O2 in a 1:2 ratio of Pt: H2O2, in CH2Cl2 producing complex 2·H2O in higher yields in both gold and red forms. Despite the color difference, red and yellow 2·H2O have the same structure as determined by single-crystal and X-ray powder diffraction, namely, an octahedral ligand array with a chelating organoamide, pyridine and chloride ligands in the equatorial plane, and axial hydroxido ligands. When tetrabutylammonium chloride was used as a chloride source, in CH2Cl2, another solvate, [PtIV{(p-BrC6F4)NCH2CH2NEt2}Cl(OH)2(py)].0.5CH2Cl2, 3·0.5CH2Cl2, was obtained. These PtIV compounds show reductive dehydration into PtII [Pt{(p-BrC6F4)NCH=CHNEt2}Cl(py)], 1H over time in the solid state, as determined by X-ray powder diffraction, and in solution, as determined by 1H and 19F NMR spectroscopy and mass spectrometry. 1H contains an oxidized coordinating ligand and was previously obtained by oxidation of 1 under more vigorous conditions. Experimental data suggest that oxidation of the ligand is favored in the presence of excess H2O2 and elevated temperatures. In contrast, a smaller amount (1Pt:2H2O2) of H2O2 at room temperature favors the oxidation of the metal and yields platinum(IV) complexes

Quantitative resistance can lead to evolutionary changes in traits not targeted by the resistance QTLs.

This paper addresses the general concern in plant pathology that the introduction of quantitative resistance in the landscape can lead to increased pathogenicity. Hereto, we study the hypothetical case of a quantitative trait loci (QTL) acting on pathogen spore production per unit lesion area. To regain its original fitness, the pathogen can break the QTL, restoring its spore production capacity leading to an increased spore production per lesion. Or alternatively, it can increase its lesion size, also leading to an increased spore production per lesion. A data analysis shows that spore production per lesion (affected by the resistance QTL) and lesion size (not targeted by the QTL) are positively correlated traits, suggesting that a change in magnitude of a trait not targeted by the QTL (lesion size) might indirectly affect the targeted trait (spore production per lesion). Secondly, we model the effect of pathogen adaptation towards increased lesion size and analyse its consequences for spore production per lesion. The model calculations show that when the pathogen is unable to overcome the resistance associated QTL, it may compensate for its reduced fitness by indirect selection for increased pathogenicity on both the resistant and susceptible cultivar, but whereby the QTLs remain effective.Rothamsted Research receives support from the Biotechnology and Biological Sciences Research Council (BBSRC) of the United Kingdom. F v d Berg was funded by an INRA-BBSRC funded project entitled ‘Epidemiological and evolutionary models for invasion and persistence of disease’. CAG gratefully acknowledges support of a BBSRC Professional Fellowship