Transition metal complexes coordination magnetic properties

Transition metal complexes are interesting as bio-inorganic model systems [155-157] and also because of their material properties (conductivity, magnetism, porosity) and as potential hosts for a variety of guests [156-161]. Whereas salt-like 2D-Cun-coordination polymers are well documented [158-162], far less is known about their neutral counterparts. 

The splitting of the d subshell in transition metal complexes is dependent on the type of ligands coordinated, with variation sufficient to lead, for some configurations, to high-spin and low-spin options that produce different spectroscopic and magnetic properties. 

Scientists have long recognized that many of the magnetic properties and colors of transition-metal complexes are related to the presence of d electrons in the metal cation. In this section we consider a model for bonding in transition-metal complexes, crystal-field theory, that accounts for many of the observed properties of these substances. Because the predictions of crystal-field theory are essentially the same as those obtained with more advanced molecular-orbital theories, crystal-field theory is an excellent place to start in considering the electronic structure of coordination compounds. 

A satisfactory theory of bonding in coordination compounds must account for properties such as color and magnetism, as well as stereochemistry and bond strength. No single theory as yet does aU this for us. Rather, several different approaches have been applied to transition metal complexes. We will consider only one of them here—crystal field theory— because it accounts for both the color and magnetic properties of many coordination compounds. 

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