Franke_reactivity_of_uranium(IV)
... solvent molecules. The bridging Se42 moiety features alternating Se–Se bond distances with two very similar bond lengths with Se1–Se2 at 2.316(2) and Se3–Se4 at 2.310(2) Å as well as a slightly larger bond distance of 2.438(1) Å for Se2–Se3 (Table 1). Thus, the bridging Se42 unit is reminiscent ...
... solvent molecules. The bridging Se42 moiety features alternating Se–Se bond distances with two very similar bond lengths with Se1–Se2 at 2.316(2) and Se3–Se4 at 2.310(2) Å as well as a slightly larger bond distance of 2.438(1) Å for Se2–Se3 (Table 1). Thus, the bridging Se42 unit is reminiscent ...
- White Rose Research Online
... adduct {Zn[Ru(ttpy)(CN)3]}+ in which, presumably, those coordination sites around the Zn2+ ion that are not occupied by cyanide ligands are occupied by MeCN solvent molecules, water molecules [since the Zn(ClO4)2 is hydrated] and/or perchlorate anions. The calculated best fit (as used in Figure 5) f ...
... adduct {Zn[Ru(ttpy)(CN)3]}+ in which, presumably, those coordination sites around the Zn2+ ion that are not occupied by cyanide ligands are occupied by MeCN solvent molecules, water molecules [since the Zn(ClO4)2 is hydrated] and/or perchlorate anions. The calculated best fit (as used in Figure 5) f ...
AP Chemistry - Oak Park Unified School District
... and the electron leaves the atom or ionizes. The lowest energy is n = 1; this is called the (7) state. Other values of n correspond to (8) states. Light is (9) when the electron drops from a higher energy state to a lower energy state and light is (10) when excited from a lower energy state to a hig ...
... and the electron leaves the atom or ionizes. The lowest energy is n = 1; this is called the (7) state. Other values of n correspond to (8) states. Light is (9) when the electron drops from a higher energy state to a lower energy state and light is (10) when excited from a lower energy state to a hig ...
Alan J. Heeger Department of Physics and Institute for Polymers and Organic Solids
... Since even a few percent error in R(ω) is crucial to the Kramers-Kronig (K-K) analysis, extra care was taken in all procedures for obtaining absolute values for R(ω). Surface quality is essential for accurate reflectance measurements. Therefore, the surface morphology of each film was checked, both ...
... Since even a few percent error in R(ω) is crucial to the Kramers-Kronig (K-K) analysis, extra care was taken in all procedures for obtaining absolute values for R(ω). Surface quality is essential for accurate reflectance measurements. Therefore, the surface morphology of each film was checked, both ...
Chapter 9 Coordination Chemistry I: Structure and Isomers
... The key breakthrough occurred when Alfred Werner proposed, inter alia, that Co(III) bears six ligands in an octahedral geometry. The theory allows one to understand the difference between coordinated and ionic chloride in the cobalt ammine chlorides and to explain many of the previously inexplicable ...
... The key breakthrough occurred when Alfred Werner proposed, inter alia, that Co(III) bears six ligands in an octahedral geometry. The theory allows one to understand the difference between coordinated and ionic chloride in the cobalt ammine chlorides and to explain many of the previously inexplicable ...
Structural Features of a Sulfur-Containing Group 4 Metalla[11
... cation complexation [1]. If one of the hydrocarbyl moieties is exchanged by an electrophilic metal center then the interesting possibility arises that an internal coordination to the metal center may occur. In the case of incorporation of e. g. a [Ti]Cl 2 or [Zr]Cl2 unit into the crown ether framewo ...
... cation complexation [1]. If one of the hydrocarbyl moieties is exchanged by an electrophilic metal center then the interesting possibility arises that an internal coordination to the metal center may occur. In the case of incorporation of e. g. a [Ti]Cl 2 or [Zr]Cl2 unit into the crown ether framewo ...
Preparation of Mn(acac)
... in the presence of acetylacetone giving the brown acetylacetonemanganese(III), Mn(acac)3. Because the ground state for octahedral complexes like that of Mn(acac)3 is a 5Eg (t2g3eg1) there exists considerable Jahn-Teller distortion. Therefore, the complexes are not “pure” octahedral. Two forms of Mn( ...
... in the presence of acetylacetone giving the brown acetylacetonemanganese(III), Mn(acac)3. Because the ground state for octahedral complexes like that of Mn(acac)3 is a 5Eg (t2g3eg1) there exists considerable Jahn-Teller distortion. Therefore, the complexes are not “pure” octahedral. Two forms of Mn( ...
MODEL 324 ADDENDUM Please make the ,following changes in
... Figure 6, step .15 - cnange entire step as follows~ 15. ( ) Fig. 6/ Connect ~he 2.2K ohm resistor R~ from TB4-l (S) to TBI-IB. (C). Note that terminal strip TBl has one insulated double lug. For reference purposes, the end of the double lug nearest TB4 is designated TB1-l,B1 and the opposite end is ...
... Figure 6, step .15 - cnange entire step as follows~ 15. ( ) Fig. 6/ Connect ~he 2.2K ohm resistor R~ from TB4-l (S) to TBI-IB. (C). Note that terminal strip TBl has one insulated double lug. For reference purposes, the end of the double lug nearest TB4 is designated TB1-l,B1 and the opposite end is ...
crystals
... Hf0.86I3 or HfI3.50, because we have, with an ample excess of the reductant aluminum, at temperatures of 850 °C or 600 °C first reached the most reduced end, HfI3, and then, by slow cooling―hence in equilibrium―the composition gradually reaches the least reduced end of the non-stoichiometry range, H ...
... Hf0.86I3 or HfI3.50, because we have, with an ample excess of the reductant aluminum, at temperatures of 850 °C or 600 °C first reached the most reduced end, HfI3, and then, by slow cooling―hence in equilibrium―the composition gradually reaches the least reduced end of the non-stoichiometry range, H ...
- skv institute
... 4. What is dipole-dipole force? In HCl molecule the chlorine atom is more electronegative than hydrogen atom, so the chlorine atom acquires partial negative charge and hydrogen atom acquires partial positive charge, hence there is a dipolar interactive attraction between two HCl molecules and such ...
... 4. What is dipole-dipole force? In HCl molecule the chlorine atom is more electronegative than hydrogen atom, so the chlorine atom acquires partial negative charge and hydrogen atom acquires partial positive charge, hence there is a dipolar interactive attraction between two HCl molecules and such ...
Potentiometry and NMR studies of 1,5,9
... pH potentiometry are shown in Table 11, where the protonation constants of [ 121ane-N,, as well as [9]ane-N3 and NOTA3- are also presented. From a comparison of these data it can be seen that all protonation constants of the 12-membered-ring ligands are higher than those of the 9-membered-ring ligan ...
... pH potentiometry are shown in Table 11, where the protonation constants of [ 121ane-N,, as well as [9]ane-N3 and NOTA3- are also presented. From a comparison of these data it can be seen that all protonation constants of the 12-membered-ring ligands are higher than those of the 9-membered-ring ligan ...
Functional group migrations between boron and
... scorpionate ligands to sting. Originally, the sting was considered as the coordination of the third ‘‘arm’’ of the ligand to a metal centre. However, this perception was altered when it was discovered that the ‘‘hydride species’’ from the borohydride unit could be transferred to the metal centre (i. ...
... scorpionate ligands to sting. Originally, the sting was considered as the coordination of the third ‘‘arm’’ of the ligand to a metal centre. However, this perception was altered when it was discovered that the ‘‘hydride species’’ from the borohydride unit could be transferred to the metal centre (i. ...
Quantum Chemistry
... the argon solvent is retained. We have found that metal-metal clustering is severely limited with 266 nm MPI of Fe(CO)5 we have instead found that these conditions generate Ar solvated metal ions. The main cluster series in the mass spectrum are Fe+Arn which is the strongest followed by Fe(CO) +Arn ...
... the argon solvent is retained. We have found that metal-metal clustering is severely limited with 266 nm MPI of Fe(CO)5 we have instead found that these conditions generate Ar solvated metal ions. The main cluster series in the mass spectrum are Fe+Arn which is the strongest followed by Fe(CO) +Arn ...
Large Polyoxotitanate Clusters
... Only 3 could be isolated in quantities sufficient for UV/vis spectroscopy. The spectra of this compound, shown in Figure 3, are remarkably similar to the spectra of the Ti17 clusters reported previously.7 At high loading densities (6.3 g/L), the absorption onset occurs at approximately 350 nm; the o ...
... Only 3 could be isolated in quantities sufficient for UV/vis spectroscopy. The spectra of this compound, shown in Figure 3, are remarkably similar to the spectra of the Ti17 clusters reported previously.7 At high loading densities (6.3 g/L), the absorption onset occurs at approximately 350 nm; the o ...
Nickel(II)-induced activation of a carbon–nitrogen
... empirical absorption correction 12 was applied. All nonhydrogen atoms were refined with anisotropic thermal parameters. For compound 3, however, non-hydrogen atoms other than oxygen were refined anisotropically. Hydrogen atoms were included at calculated positions, updated after each cycle of refinemen ...
... empirical absorption correction 12 was applied. All nonhydrogen atoms were refined with anisotropic thermal parameters. For compound 3, however, non-hydrogen atoms other than oxygen were refined anisotropically. Hydrogen atoms were included at calculated positions, updated after each cycle of refinemen ...
Iron Oxyhydroxide Aerogels and Xerogels by Hydrolysis of FeCl3 ∙ 6
... Commencement of hydrolysis results in significant increase of recoilless fractions in the spectra, i.e. the organic ligands are replaced with hydroxo- and/or with oxo bridges (Figure 6). The differences in the rate of hydrolysis can be compared and interpreted in the three solvents in further detail ...
... Commencement of hydrolysis results in significant increase of recoilless fractions in the spectra, i.e. the organic ligands are replaced with hydroxo- and/or with oxo bridges (Figure 6). The differences in the rate of hydrolysis can be compared and interpreted in the three solvents in further detail ...
Ni complexes of redox-active pincers with pendant H-bonding sites
... we also attempted to assign the number of electrons for each of the observed transitions, by comparing the electrochemical response against a ferrocene standard SWV at the same concentration as the analyte under study. This analysis is of course contingent upon the diffusional coefficient of ferrocen ...
... we also attempted to assign the number of electrons for each of the observed transitions, by comparing the electrochemical response against a ferrocene standard SWV at the same concentration as the analyte under study. This analysis is of course contingent upon the diffusional coefficient of ferrocen ...
3.014 MATERIALS LABORATORY MODULE β-2
... reason the value of Cp,m at room temperature is close to 3R where R=k NA is the Universal gas constant. ● For halite structures such as NaCl, atoms of Cl arrange in a face centered cubic structure, with Na atoms occupying the octahedral sites; thus one mole of NaCl consists of NA sodium atoms and NA ...
... reason the value of Cp,m at room temperature is close to 3R where R=k NA is the Universal gas constant. ● For halite structures such as NaCl, atoms of Cl arrange in a face centered cubic structure, with Na atoms occupying the octahedral sites; thus one mole of NaCl consists of NA sodium atoms and NA ...
H - Chemical Biology Research Group
... - E.g. alkali, alkali earth metals prefer O, amine, amide N; late transition metals prefer imine N, and S donors ...
... - E.g. alkali, alkali earth metals prefer O, amine, amide N; late transition metals prefer imine N, and S donors ...
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).