Ligand strength

All these studies demonstrated that water stability of MOFs can be improved by incorporating specific factors (e.g., metal-ligand strength, thermodynamic and kinetic factors, etc.) which govern the structural stability of the framework. 

The functional characteristic of these compounds that is of interest from the viewpoint of textile processing is their capability to accommodate alkaline-earth and alkali metal cations, as well as a variety of other species, within their cavities. Stability constants (Equation 10.3) are again used, both as a measure of ligand strength and as a hierarchical indicator of... 

Ligand affinity series of more bare metal ions and one-coordinate ions are needed to understand the effect of the electronic structure of the ion on ligand strength. The study of catalytic cycles in the gas phase (especially where they relate to condensed phase catalysis) appears to be a growth area for the future. 

Ligand displacement reactions for [MX]+ and [MX2]+ ions may be used as a measure of ligand strength for a wide variety of donor molecules. The M-O bond in the [MO]+ ion varies from very strong for the groups 3 (IIIB), 4 (IVB), and 5 (VB) metals to weak in the later transition metals. 

A systemic study of compounds containing O, O N, O and S, O ligand sets has been conducted in which the effect of variables such as the steric bulk of the groups on the metal and on the ligand, strength of the Lewis base donor, and size of the chelate ring formed when the ligand becomes bidentate has... 

Figure 13. The term diagram of the Cu(Il)-0, complex at —= 90°, 0 = 44°, and varying Ot ligand strength G/. Vertical bars indicate the positions of experimentally observed bands of Figure 9c.

A particularly detailed description was obtained for complexes of Co- A zeolite with mono-olefins (24). Steric effects due to methyl groups adjacent to the double bond resulted in the ligand strength spectrochemical series... 

The ancillary ligands modulate the oxidation and reduction potentials as a consequence of their different ligand strength and electron-withdrawal capability toward the metal d orbitals, see Fig. 3. The overall effect goes along the sequence GST > NCS > NCCT, i.e., the highest first oxidation and easiest first reduction, + 1.42 and - 1.19 V vs. SCE, respectively, are observed for Ir(ppy)2(CN)2 . Accordingly, Ir(ppy)2(CN)2 results in a blue emitter, Xem = 470 nm. 

A number of articles have focused on the general issues of structure, stability, donor properties, and ligand strength of neutral ligand TiCl4 adducts. Generally these works have involved use of various spectroscopic techniques including NQR, X-ray fluorescence, and NMR spectroscopy.11-15... 

Examination of the i.r. spectra of solutions of aluminium(III) chloride with competing ligands has led to the following series of ligand strengths, with phosgene notably the weakest of those studied [1050] ... 

This work shows the spectroscopic characteristics of ammonia in the presence of Cu and Co " " cations exchanged in the Faujasite-X zeolite and its ligand strength. This data may be used to identify and semi-quantify the presence of ammonia in the presence of pyridine, acetone and water. Specifically, both DRS and IR need to be used together in any attempt to formalize the sensoring of ammonia in the environment. Further research is, however, needed to quantify ammonia in the environment. 

To summarize the present results, Co (II) ions can be introduced into the Type A molecular sieves into the S-II type positions, where they are stable and resist both oxidation and reduction. These ions bind nitrous oxide, cyclopropane, water, and ammonia as additional ligands, their spectra being simultaneously changed in a defined fashion. The spectrochemical series of these ligands is, in the order of increasing ligand strength,... 

A qualitative assessment of the relative ligand strengths of interaction between nitrate ion, water and four organic solvents and a number of 4-3 lanthanide ions was made from changes in f-f transitions. The affinity series of the lanthanides for the nitrate ion and the solvents was DMF > tributylphosphate > NO3 H2O > EtOH > dioxan. In DMF, hexadimethylformamide-lanthanides were the only complexes present, although conductivity measurements showed a major portion of the nitrate ion to be ion-paired, while in anhydrous dioxan the solvent-solute interaction is so weak that the rubidium-lanthanide nitrate double salts employed were not soluble. In water, in the absence of excess nitrate ion, hexaquo-lanthanide complexes predominate with little nitrate ion-association, in line with better nitrate solvation in protic solvents. 

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