Carbonyl-phosphine hetero-ligated half-metallocene iron(II
... beyond chemistry. ‘Transition metal-catalyzed’ living radical polymerization (Scheme 1) is one of several such systems in which metal catalysts are responsible not only for mediating initiation and propagation but also for molecular weight control, reaction rate and the range of applicable monomers, ...
... beyond chemistry. ‘Transition metal-catalyzed’ living radical polymerization (Scheme 1) is one of several such systems in which metal catalysts are responsible not only for mediating initiation and propagation but also for molecular weight control, reaction rate and the range of applicable monomers, ...
NO bond in a Ruthenium nitrosyl complex
... DFT18 due to its single Slater determinant approximation. In this respect, Kohn–Sham DFT is conceptually similar to Hartree– Fock theory, which does not incorporate electron correlation (i.e. movement of electrons depending on the instantaneous positions of other electrons). Electron correlation can ...
... DFT18 due to its single Slater determinant approximation. In this respect, Kohn–Sham DFT is conceptually similar to Hartree– Fock theory, which does not incorporate electron correlation (i.e. movement of electrons depending on the instantaneous positions of other electrons). Electron correlation can ...
http://doc.rero.ch
... Ethers in general (THF, Et2 O, etc.) are among the most frequently used solvents for alkali metal compounds. They are usually polar enough to dissolve group 1 compounds with ionic character because they are able to coordinate to the metal ions. By acting as “chemical scissors” on alkali metal salts, ...
... Ethers in general (THF, Et2 O, etc.) are among the most frequently used solvents for alkali metal compounds. They are usually polar enough to dissolve group 1 compounds with ionic character because they are able to coordinate to the metal ions. By acting as “chemical scissors” on alkali metal salts, ...
Chapter 5 - DORAS
... synthetic chemistry and one which is becoming more significant within inorganic synthesis also. Although this reaction can proceed in various ways, the use of transition metal salts or complex catalyzed coupling is by far the most esthetic and practical method available.3 The independent discovery i ...
... synthetic chemistry and one which is becoming more significant within inorganic synthesis also. Although this reaction can proceed in various ways, the use of transition metal salts or complex catalyzed coupling is by far the most esthetic and practical method available.3 The independent discovery i ...
Chapter 1 Introduction - Heriot
... Boranes are compounds that are composed solely of boron and hydrogen and may be neutral or anionic. The chemistry of boranes was first studied systematically by Alfred Stock and his research group beginning in 1912 and continuing for almost 25 years.4 Stock developed the glass vacuum line and techni ...
... Boranes are compounds that are composed solely of boron and hydrogen and may be neutral or anionic. The chemistry of boranes was first studied systematically by Alfred Stock and his research group beginning in 1912 and continuing for almost 25 years.4 Stock developed the glass vacuum line and techni ...
A Long Journey in Lanthanide Chemistry: From Fundamental
... particularly appealing, as one can try to reproduce classic tricolor association used in commercial devices.38 We chose to use Ce3+ ions, whose pure phase exhibits blue emission, and to combine it with the red (Eu3+) and green (Tb3+) emission. We were then able to elaborate some kind of ternary phas ...
... particularly appealing, as one can try to reproduce classic tricolor association used in commercial devices.38 We chose to use Ce3+ ions, whose pure phase exhibits blue emission, and to combine it with the red (Eu3+) and green (Tb3+) emission. We were then able to elaborate some kind of ternary phas ...
ADVANCED APPLICATIONS OF X
... protein metal sites of biological relevance and as the development of methods aimed to improve the XAS analysis itself. A consistent part of this work will concern the high-resolution determination of metal binding clusters in energy transducing membrane proteins, for which X-ray Absorption Fine Str ...
... protein metal sites of biological relevance and as the development of methods aimed to improve the XAS analysis itself. A consistent part of this work will concern the high-resolution determination of metal binding clusters in energy transducing membrane proteins, for which X-ray Absorption Fine Str ...
“Synthetic Mononuclear Nonheme Iron
... CONSPECTUS: Mononuclear nonheme iron−oxygen species, such as iron− superoxo, −peroxo, −hydroperoxo, and −oxo, are key intermediates involved in dioxygen activation and oxidation reactions catalyzed by nonheme iron enzymes. Because these iron−oxygen intermediates are short-lived due to their thermal ...
... CONSPECTUS: Mononuclear nonheme iron−oxygen species, such as iron− superoxo, −peroxo, −hydroperoxo, and −oxo, are key intermediates involved in dioxygen activation and oxidation reactions catalyzed by nonheme iron enzymes. Because these iron−oxygen intermediates are short-lived due to their thermal ...
The electronic state of thin films of yttrium, yttrium
... [2]. Yttrium hydride is generally considered to belong to the class of the rare-earth metal hydrides, for which the metal-hydrogen phase diagram is divided in three phases [3]; the metallic phase with dissolved small amounts of hydrogen is called the α-phase; the metallic dihydride (YH2) is known as ...
... [2]. Yttrium hydride is generally considered to belong to the class of the rare-earth metal hydrides, for which the metal-hydrogen phase diagram is divided in three phases [3]; the metallic phase with dissolved small amounts of hydrogen is called the α-phase; the metallic dihydride (YH2) is known as ...
View/Open
... hydrogen bonds, and therefore have higher boiling points than hydrocarbons of the same molecular weight. Phenol (bp 182 8C) has a boiling point more than 70 8C higher than toluene (bp 110.6 8C), even though the two compounds have almost the same molecular weight. Phenols are also modestly soluble i ...
... hydrogen bonds, and therefore have higher boiling points than hydrocarbons of the same molecular weight. Phenol (bp 182 8C) has a boiling point more than 70 8C higher than toluene (bp 110.6 8C), even though the two compounds have almost the same molecular weight. Phenols are also modestly soluble i ...
STRUcruR.AL ASPEcrs AND COORDINATION CHEMISTRY OF
... Ru(TPP)CO(Py) and Ru(TPP)CO(EtOH). respectively). In view of this and other data of model compounds [19], the "bent" or "tilted" geometry reported for the CO ligand in several carbonyl hemoproteins [20-24] has usually been attributed to sterle constraints placed on the porphyrin coordination sphere ...
... Ru(TPP)CO(Py) and Ru(TPP)CO(EtOH). respectively). In view of this and other data of model compounds [19], the "bent" or "tilted" geometry reported for the CO ligand in several carbonyl hemoproteins [20-24] has usually been attributed to sterle constraints placed on the porphyrin coordination sphere ...
A Tungsten(VI) Nitride Having a W ( Core µ
... confirmed through an X-ray diffraction study of W(15NSiMe3)(CH2-t-Bu)(OAr)2(OTf) (Figure 11). Due to a destructive phase change in the crystal near -60 °C, diffraction data had to be collected at -55 °C. Consequently, the triflate ligand was disordered, and the thermal motion of the atoms was greate ...
... confirmed through an X-ray diffraction study of W(15NSiMe3)(CH2-t-Bu)(OAr)2(OTf) (Figure 11). Due to a destructive phase change in the crystal near -60 °C, diffraction data had to be collected at -55 °C. Consequently, the triflate ligand was disordered, and the thermal motion of the atoms was greate ...
Selective Hydrogenation of Acetylene over
... recording the spectrum. They were derived by subtracting Pd( 111) + H2 spectra from P d ( l l 1 ) + H2 + C2H2spectra obtained a t corresponding temperatures; thus they exhibit only acetylenederived features. A difference spectrum for H2 alone at 209 K is shown for-comparison purposes. The photon inc ...
... recording the spectrum. They were derived by subtracting Pd( 111) + H2 spectra from P d ( l l 1 ) + H2 + C2H2spectra obtained a t corresponding temperatures; thus they exhibit only acetylenederived features. A difference spectrum for H2 alone at 209 K is shown for-comparison purposes. The photon inc ...
III. Solubility Equilibria Solbility and Equilibrium
... Complex Ions Complex ion: a charged species consisting of a metal ion surrounded by ligands Ligands: ions or molecules that bond to a metal ion. Common ligands include Cl-, F-, CN-, OH-, NH3, and H2O Coordination Number: the number of ligands that surround a metal ion. In general, the coordination ...
... Complex Ions Complex ion: a charged species consisting of a metal ion surrounded by ligands Ligands: ions or molecules that bond to a metal ion. Common ligands include Cl-, F-, CN-, OH-, NH3, and H2O Coordination Number: the number of ligands that surround a metal ion. In general, the coordination ...
Precipitation titration
... To detect silver ion : a standard sol. of thiocyanate is use as a titrant for silver ion . Iron ion (III) is use as an indicator imparting a red coloration to sol. with first slightly excess of thiocyanate. ...
... To detect silver ion : a standard sol. of thiocyanate is use as a titrant for silver ion . Iron ion (III) is use as an indicator imparting a red coloration to sol. with first slightly excess of thiocyanate. ...
Elucidation of Mechanisms and Selectivities of Metal
... reactions, a consistent mechanism is presented, the experimentally observed selectivities are reproduced, and their sources are identified. Reproducing selectivities requires high accuracy in computing relative transition state energies. As demonstrated by the results summarized in this Account, this ...
... reactions, a consistent mechanism is presented, the experimentally observed selectivities are reproduced, and their sources are identified. Reproducing selectivities requires high accuracy in computing relative transition state energies. As demonstrated by the results summarized in this Account, this ...
RSC_NJ_C1NJ20460B 1..7
... complex stability order observed for metal catechol complexes.25 La(catechol)+ is the weakest (log Kf = 1.52 at pH 7.0) and Fe(catechol)+ (log Kf = 11.8 at pH 7.0) the most stable complex. The quenching efficiency of Fe, Sc, Al and Cu does not follow metal–catechol complex stability, suggesting that s ...
... complex stability order observed for metal catechol complexes.25 La(catechol)+ is the weakest (log Kf = 1.52 at pH 7.0) and Fe(catechol)+ (log Kf = 11.8 at pH 7.0) the most stable complex. The quenching efficiency of Fe, Sc, Al and Cu does not follow metal–catechol complex stability, suggesting that s ...
Synthesis and characterization of superparamagnetic iron oxide
... organism media; inert shell provides non-toxicity, stability and polyfunctionality, being a suitable platform for variety of ligands2. The great potential of nanotechnologies makes them the most perspective field of scientific interest. In the nearest future nanodevices will help us in any aspect of ...
... organism media; inert shell provides non-toxicity, stability and polyfunctionality, being a suitable platform for variety of ligands2. The great potential of nanotechnologies makes them the most perspective field of scientific interest. In the nearest future nanodevices will help us in any aspect of ...
Spin crossover
Spin Crossover (SCO), sometimes referred to as spin transition or spin equilibrium behavior, is a phenomenon that occurs in some metal complexes wherein the spin state of the complex changes due to external stimuli such as a variation of temperature, pressure, light irradiation or an influence of a magnetic field.With regard to a ligand field and ligand field theory, the change in spin state is a transition from a low spin (LS) ground state electron configuration to a high spin (HS) ground state electron configuration of the metal’s d atomic orbitals (AOs), or vice versa. The magnitude of the ligand field splitting along with the pairing energy of the complex determines whether it will have a LS or HS electron configuration. A LS state occurs because the ligand field splitting (Δ) is greater than the pairing energy of the complex (which is an unfavorable process).Figure 1 is a simplified illustration of the metal’s d orbital splitting in the presence of an octahedral ligand field. A large splitting between the t2g and eg AOs requires a substantial amount of energy for the electrons to overcome the energy gap (Δ) to comply with Hund’s Rule. Therefore, electrons will fill the lower energy t2g orbitals completely before populating the higher energy eg orbitals. Conversely, a HS state occurs with weaker ligand fields and smaller orbital splitting. In this case the energy required to populate the higher levels is substantially less than the pairing energy and the electrons fill the orbitals according to Hund’s Rule by populating the higher energy orbitals before pairing with electrons in the lower lying orbitals. An example of a metal ion that can exist in either a LS or HS state is Fe3+ in an octahedral ligand field. Depending on the ligands that are coordinated to this complex the Fe3+ can attain a LS or a HS state, as in Figure 1.Spin crossover refers to the transitions between high to low, or low to high, spin states. This phenomenon is commonly observed with some first row transition metal complexes with a d4 through d7 electron configuration in an octahedral ligand geometry. Spin transition curves are a common representation of SCO phenomenon with the most commonly observed types depicted in Figure 2 in which γHS (the high-spin molar fraction) is plotted vs. T. The figure shows a gradual spin transition (left), an abrupt transition with hysteresis (middle) and a two-step transition (right). For a transition to be considered gradual, it typically takes place over a large temperature range, even up to several hundred K, whereas for a transition to be considered abrupt, it should take place within 10 K or less.These curves indicate that a spin transition has occurred in a metal complex as temperature changed. The gradual transition curve is an indication that not all metal centers within the complex are undergoing the transition at the same temperature. The abrupt spin change with hysteresis indicates a strong cooperativity, or “communication”, between neighboring metal complexes. In the latter case, the material is bistable and can exist in the two different spin states with a different range of external stimuli (temperature in this case) for the two phenomena, namely LS → HS and HS → LS. The two-step transition is relatively rare but is observed, for example, with dinuclear SCO complexes for which the spin transition in one metal center renders the transition in the second metal center less favorable.There are several types of spin crossover that can occur in a complex; some of them are light induced excited state spin trapping (LIESST), ligand-driven light induced spin change (LD-LISC), and charge transfer induced spin transition (CTIST).