Magnesium-Nitrogen complexes, structural

Within this overview of copper(I), lithium, and magnesium thiolate complexes, one of the aims is to highlight the influence that (intramolecular) nitrogen coordination exerts on the structure of such species, since intermolecular (auxiliary) coordination of heteroatoms often leads to poorly defined species. An example of this poor species definition is the reaction behavior of polymeric copper(I) thiophenolate, [Cu(SPh)]. with triphenylphosphine Several P-coordinated aggregates with variable stoichiometry were reported (Scheme 1) (27-29). This behavior makes it difficult to study one specific species in cop-per(I) thiolate catalyzed organic reactions since equilibria are likely to occur. 

One of the important properties of porphyrins is that they complex with divalent metals, the pyrrole nitrogens being ideally spaced to allow this. Of vital importance to life processes are the porphyrin derivatives chlorophyll and haem. Chlorophyll (actually a mixture of structurally similar porphyrins chlorophyll a is shown) contains magnesium, and is, of course, the light-gathering pigment in plants that permits photosynthesis. 

A common treatment for metal intoxication is the use of chelators. A chelator is a flexible molecule with two or more electronegative groups that can form stable complexes with cationic metal atoms. The complexes are then eliminated from the body. The most widely used chelator is eth-ylenediaminetetraacetic acid (EDTA). It has four binding positions (two nitrogen atoms and two oxygen atoms) that focus on the metal ion. It works very well on many metals, the most notable being calcium, magnesium, and lead, see also Enzymes Proteins Tertiary Structure Toxicity. 

The high optical yields depend at least in part on complexation of the magnesium atom with the ring nitrogen and the carbonyl group to form a rigid structure. 

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