Search results for "Ordination"
showing 10 items of 1367 documents
Controlling the molecular diffusion in MOFs with the acidity of monocarboxylate modulators.
2021
The catalytic performance of metal-organic frameworks (MOFs) is related to their physicochemical properties, such as particle size, defect-chemistry and porosity, which synthetic control can be potentially achieved by coordination modulation. By combining PXRD, 1HNMR, FT-IR, N2 uptake measurements we have found insights that the different types of defects (missing linker or missing clusters consequence of the spatial distribution of missing linkers, and the combination of both) could be controlled by the type of modulator employed. We show that the molar percent of defects, either as missing linkers or as part of missing cluster defects, is related to the modulator’s acidity and subse…
Quantitative Analysis of the Interactions of Metal Complexes and Amphiphilic Systems: Calorimetric, Spectroscopic and Theoretical Aspects.
2022
Metals and metal-based compounds have many implications in biological systems. They are involved in cellular functions, employed in the formation of metal-based drugs and present as pollutants in aqueous systems, with toxic effects for living organisms. Amphiphilic molecules also play important roles in the above bio-related fields as models of membranes, nanocarriers for drug delivery and bioremediating agents. Despite the interest in complex systems involving both metal species and surfactant aggregates, there is still insufficient knowledge regarding the quantitative aspects at the basis of their binding interactions, which are crucial for extensive comprehension of their behavior in sol…
Molecular Dynamics Computer Simulation of Cooling Rate Effects in a Lennard-Jones Glass
1995
We present the results of a molecular dynamics computer simulation of a binary Lennard-Jones mixture. We simulate a quench of the system from a liquid state at high temperatures to a glass state at zero temperature by coupling the system to a heat bath that has a temperature that decreases linearly (with slope -γ) with time. We investigate how the residual density of the system varies as a function of the cooling rate γ and rationalize our results by means of the dependence of the coordination number of the particles on the cooling rate.
Synthesis and characterization of [Mo(μ-EPh)(CO)3(CH3CN)]2 (E=Se, Te), including the X-ray structure of the tellurium derivative
2000
International audience; The reaction of Mo(CO)3(MeCN)3 and E2Ph2 (E=Se, Te) yields the edge-sharing bioctahedral, metalmetal bonded Mo(I) products [Mo(CO)3(MeCN)(μ-EPh)]2. The structure of the tellurolato derivative was confirmed by X-ray crystallography: triclinic, space group , a=7.3149(17), b=9.6959(16), c=9.7090(10) Å, α=80.366(10), β=76.563(13), γ=72.877(16)°, V=636.43(19) Å3, Dcalc=2.222 Mg m−3, μ=3.271 mm−1, R1=0.0418, wR2=0.0689 for 163 parameters and 2238 data with I>2σ(I). The interaction of these compounds with excess E2Ph2 as a possible entry to homoleptic Mo(EPh)3 has been investigated.
Diene-Containing Half-Sandwich MoIII Complexes as Ethylene Polymerization Catalysts: Experimental and Theoretical Studies
2001
International audience; Seventeen-electron compounds of Mo III having the general formula [(h 5-C 5 R 5)Mo(h 4-diene)X 2 ] (R H, Me; diene butadiene, iso-prene, or 2,3-dimethylbutadiene; X Cl, CH 3) are a new class of ethylene polymerization catalysts. The polyethy-lene obtained shows a bimodal distribution , the major weight fraction being characterized by very long (M around 10 6) and highly linear polymer chains. The newly prepared pentamethylcyclo-pentadienyl (Cp*) derivatives are more active than the cyclopentadienyl (Cp) derivatives, but much less active than previously investigated niobium III compounds having the same stoichiometry. On the other hand, the turnover frequency of the a…
Cyclopentadienylmolybdenum(VI) and molybdenum(V) oxo chemistry: New synthetic and structural features
2002
International audience; Convenient syntheses for Cp, Cp*, and related cyclopentadienyl derivatives (4Cp = C5HiPr4; Cp′′′ = C5H2tBu3-1,2,4) of formula [(Ring)2Mo2O5] are described. Compound [Cp2Mo2O5] was produced in good yields by the rapid oxidation of red [CpMoO2]4 with PhIO in CH2Cl2. [Cp*2Mo2O5] was obtained by CH3COOH acidification of aqueous solutions of [Cp*MoO3]−Na+, the latter being generated in a single step from [Cp*MoCl4] and more than 5 equiv. of aqueous NaOH in air. Minor quantities of [Cp*MoO2]2 were also isolated from this reaction, although the formation of this by-product may be reduced by using a two-step basic hydrolysis procedure. Extension of the latter strategy also a…
A Bis(diazadiene) Adduct of MoCl 2 : Mononuclear, Octahedral, Undistorted and Diamagnetic
2004
The complex [MoCl2(iPr2dad)2] (iPr2dad = iPrN=CH−CH=N−iPr) is obtained in one step by reduction of [MoCl3(THF)3] in the presence of iPr2dad. The X-ray structure reveals a relatively undistorted octahedral coordination geometry with a relative cis configuration and points to a more appropriate description of the ligands as enediamides. The NMR investigation is in agreement with the same cis structure in solution and underlines the diamagnetism of the compound, at odds with previously reported very similar complexes. A bulk magnetic susceptibility measurement further confirms the compound’s diamagnetism. No equilibrium with a dinuclear, metal-metal bonded species is apparent from the solution…
Seaborgium's complex studies
2015
Christoph E. Dullmann reflects on the excitement, and implications, of probing the reactivity of heavy element seaborgium.
Mo 3 Q 7 (Q = S, Se) Clusters Containing Dithiolate/Diselenolate Ligands: Synthesis, Structures, and Their Use as Precursors of Magnetic Single‐Compo…
2013
The coordination chemistry of dithiolene and diselenolene ligands towards the all-selenium [Mo3Se7Br6]2– dianion has been investigated. Complexes (nBu4N)2[Zn(dmit)2] (dmit = 1,3-dithia-2-thioxo-4,5-dithiolate) and (nBu4N)2[Zn(dsit)2] (dsit = 1,3-dithia-2-thioxo-4,5-diselenolate) were employed as ligand precursors. The (nBu4N)2[Zn(dmit)2] complex in acetonitrile at reflux showed unexpected reactivity with [Mo3Se7Br6]2– dianion in which the inner Se atoms were replaced by S (all but the μ3-Se atom) to afford a series of mixed chalcogen [Mo3Se7–xSx(dmit)3]2– (x = 0–6) dianions. Reaction of the [Mo3S4Se3Br6]2– dianion with (nBu4N)2[Zn(dmit)2] under similar conditions also produced a mixed dmit-…
Essential oil variation within and among natural populations of Lavandula latifolia and its relation to their ecological areas
2007
Essential oil yield and composition in seven natural populations of Lavandula latifolia from the eastern Iberian Peninsula were determined by GC/MS. Twenty-eight constituents were identified, accounting for 92.0e95.4% of the total oils. These oils were dominated by the monoterpene fraction and three of them (linalool, cineole and camphor) constituted 79.5e86.9% of the oil from flowers. Essential oil yield in leaves and flowers varied among and within populations, but hierarchic analyses of variance showed that the proportion of variation attributable to individuals was significantly higher than that attributable to population differences. Principal component and cluster analyses allowed thr…