Magnetism, of coordination

Batten, S. R., Murray, K. S., Structure and magnetism of coordination polymers containing dicyanamide and tricyanemethanide. Coord. Chem. Rev. 2003, 246,103-130. 

Although CFT can explain the magnetism of coordination compounds and predict that they are colored, it is not a quantitative theory. It cannot predict, for instance, the exact color of a transition metal complex because there is no way of rationalizing the relative magnitude of a priori. Even for a metal ion having... 

Magnetic properties should be independent of the choice of coordinate origin. The term choice of origin is often translated into choice of gauge, and so we say that physical properties should be gauge-invariant (for a discussion, see Hameka, 1965). 

In ferrites, the magnetization of the B-sublattice with octahedrally coordinated cations is usually parallel to the applied field whereas the magnetization of the /l-sublattice with tetrahedrally coordinated cations is in the opposite direction. 

To obtain statistically significant comparisons of ordered and disordered sequences, much larger datasets were needed. To this end, disordered regions of proteins or wholly disordered proteins were identified by literature searches to find examples with structural characterizations that employed one or more of the following methods (1) X-ray crystallography, where absence of coordinates indicates a region of disorder (2) nuclear magnetic resonance (NMR), where several different features of the NMR spectra have been used to identify disorder and (3) circular dichroism (CD) spectroscopy, where whole-protein disorder is identified by a random coil-type CD spectrum. 

The formation of diimine systems by Schiff -base-type condensation of suitable aldehydes and primary amines has been widely applied. Those reported are mostly strong field systems and their relevance to the spin crossover field is generally in systems of the kind [Fe(diimine)2(NCS)2]. The effect of the incorporation of substituents likely to hinder coordination has been studied. Robinson and Busch noted a fundamental difference at room temperature in the electronic properties of the [Fe N6]2+ derivatives of 2-pyridi-nalmethylhydrazone and 2-pyridinal-dimethylhydrazone, those of the former being low spin and those of the latter high spin [49]. The temperature-dependence of the magnetism of the latter complex was not reported but may well be of interest. However, spin crossover [Fe(diimine)3]2+ systems have been characterised for systems where the incorporation of appropriate substituents has reduced the ligand field. 

---