Polar organometallic chemistry structures

This chapter will concentrate on the chemistry of metal-14-centered anions (Ge, Sn, Pb). These compounds and their silyl analogues are ionic or polarized alkaline and alkaline earth metal-14 compounds, as well as delocalized molecules such as metalloles. Ammonium metallates Mi4 R4N+ or metal-14-centered anion radicals are also considered. The subject was explored during the 1960s and 1970s and thoroughly reviewed in 1982 and 1995 in Comprehensive Organometallic Chemistry, Vols. I and and for silicon species in a previous volume of this series . By that time the main routes to metal-14 anions were known. Since then, the subject has been developed in the topics of particular syntheses, stabilization using steric hindrance, electronic effects and complexation, spectroscopic and structural analyses "... 

H. Wadepohl, CobaltaMvenes and Cobaltapentalenes Highly Polar MetaUacyclic 11-Systems with Unusual Properties, in Unusual Structures and Physical Properties in Organometallic Chemistry , eds. M. Gielen, R. Willem, and B. Wrackmeyer, John Wiley Sons, West Sussex, 2002. 

Lithium as the first element in the Periodic Table is expected to exhibit special properties. It is the most electronegative of the alkali elements but simultaneously the most electropositive of the Period. That is apparent in lithium chemistry, since there is, for instance, a widely used organometallic chemistry and a rich structural chemistry which is not common for the other group elements. On the other hand, high polar species and lithium bonds with great ionic character are almost a constant in lithium chemistry. The chemical... 

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