Organometallic compounds special techniques

Additionally to the theoretical data and synthetic techniques for various metal complexes presented in Chaps. 2-A, we would like to pay special attention to three kinds of coordination compounds (complexes of phthalocyanines, quinones, and radioactive elements), whose syntheses, in our opinion, have been insufficiently generalized in monographs and textbooks on synthetic coordination chemistry. This choice is caused by the facts that phthalocyanines, as n-aromatic macrocyclic compounds, possess unusual thermal stability (nonstandard for organic and organometallic species) the quinone complexes have free-radical properties and coordination and organometallic compounds of radioactive elements are interesting at least for the reasons of necessity of special precautions in their syntheses and applications in the nuclear industry and nuclear medicine. So, this chapter is dedicated to the peculiarities of structure and properties and the main synthetic procedures for the complexes above. 

It should also be mentioned at the outset that numerous organometallic compounds constitute hazardous materials. Several of them, especially those containing small alkyl groups bonded to reactive metals, are spontaneously flammable in air and react explosively with water. Others, especially those of mercury and cadmium, are extremely toxic. To make the situation worse, some of these compounds are readily absorbed through the skin. Needless to say, special precautions and laboratory techniques are necessary when working with any organometallic compounds that have these characteristics. 

Matrix-isolation is a useful technique for preparation of novel unstable compounds and investigation of chemical reactions at low temperatures. The Mbssbauer spectra of matrix-isolated species provide important information regarding the electronic state, structure, and reactions of a single atom, or a molecule in such systems (13). Since there had been no MBssbauer study on metal chelate complexes and organometallic compounds in low temperature matrices, we designed a system for MBssbauer measurements of matrix-isolated species and investigated the photochemical reactions of such systems (14). Special care was taken to avoid interference of vibrations from the refrigerating system with the MBssbauer spectrometer. 

Complexes involving low valence states, organometallic complexes for instance, are usually inert. However, inertness relates to kinetics and kinetics depend on mechanism. An organometallic compound which normally reacts slowly may spontaneously catch fire, or, less dramatically, rapidly oxidize, if exposed to air. Not surprisingly, special inert atmosphere techniques have to be used in preparing such compounds. Gaseous oxygen, of course, is a diradical, with two unpaired electrons, and so it is not unexpected that it should react rather differently to many other potential reactants. 

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