Metal complexes parameters

S.C. Rutan and S.D. Brown, Pulsed photoacoustic spectroscopy and spectral deconvolution with the Kalman filter for determination of metal complexation parameters. Anal. Chem., 55 (1983) 1707-1710. 

The modeling of inorganic compounds in general is gaining more and more interest [25-28]. The authors of MOMEC addressed this in a monograph describing how molecular modeling techniques can be applied to metal complexes and how the results can be interpreted [29]. The current force field parameter set is available on the author s web site. 

As one would expect, in those cases in which the ionic liquid acts as a co-catalyst, the nature of the ionic liquid becomes very important for the reactivity of the transition metal complex. The opportunity to optimize the ionic medium used, by variation of the halide salt, the Lewis acid, and the ratio of the two components forming the ionic liquid, opens up enormous potential for optimization. However, the choice of these parameters may be restricted by some possible incompatibilities with the feedstock used. Undesired side reactions caused by the Lewis acidity of the ionic liquid or by strong interaction between the Lewis acidic ionic liquid and, for example, some oxygen functionalities in the substrate have to be considered. 

The purity of ionic liquids is a key parameter, especially when they are used as solvents for transition metal complexes (see Section 5.2). The presence of impurities arising from their mode of preparation can change their physical and chemical properties. Even trace amounts of impurities (e.g., Lewis bases, water, chloride anion) can poison the active catalyst, due to its generally low concentration in the solvent. The control of ionic liquid quality is thus of utmost importance. 

The wide diversity of cocatalysts and transition metal complexes suggests that the oxidation state of the transition metal is not a critical parameter. More important seems the availability of vacant coordination sites. In agreement with this, in the case of heterogeneous systems also,... 

Neese, F., Solomon, E.I. Calculation and interpretation of spin-Hamiltonian parameters in transition metal complexes. In Miller, J.S., Drillon, M. (eds.) Magnetoscience - From Molecules to Materials, vol. 4, p. 345. Wiley, Weinheim (2003)... 

Atwood DA, Zaman MK (2006) Mercury Removal from Water 120 163-182 Autschbach J (2004) The Calculation of NMR Parameters in Transition Metal Complexes 112 1-48... 

In Chapter 4 (Sections 4.7 and 4.8) several examples were presented to illustrate the effects of non-coincident g- and -matrices on the ESR of transition metal complexes. Analysis of such spectra requires the introduction of a set of Eulerian angles, a, jS, and y, relating the orientations of the two coordinate systems. Here is presented a detailed description of how the spin Hamiltonian is modified, to second-order in perturbation theory, to incorporate these new parameters in a systematic way. Most of the calculations in this chapter were first executed by Janice DeGray.1 Some of the details, in the notation used here, have also been published in ref. 8. 

Factors influencing the macrocyclic hole size. The hole size of a macrocyclic ligand is a fundamental structural parameter which will usually influence, to a large degree, the properties of resultant metal complexes relative to those of the corresponding non-cyclic ligands. The large number of X-ray diffraction studies now complete for macrocyclic systems makes it possible to define many of the parameters which affect hole size... 

The most important structural parameters of the transition metal complexes are summarized in Table XXV and Figs. 35-37 display the solid state structures of three selected complexes. 

---