Organometallic compounds alkaline earth metals

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 "... 

Although the first report of an organometallic compound of the heavier alkaline earth metals appeared near the beginning of the twentieth century,291 the RMX Grignard analogs of Ca, Sr, and Ba never fulfilled their promise as general-purpose synthetic reagents. More difficult to form, less thermally stable, and less selective in their reactions than their Mg counterparts, the literature data of the compounds was often contradictory, and many syntheses were irreproducible (see Calcium, Strontium, and Barium in COMC (1982)). 

ISBN 97S-0-470-721S4-1 (cloth alk. paper) 1. Amides. 2. Alkaline earth metals. 3. Organometallic compounds. I. Lappert. M. F. 

There is also an extensive organometallic chemistry of the alkali and alkaline earth metals. Many of these compounds, particularly those of Li, Be and Mg, form coordination complexes with appropriate donor ligands. This topic has been recently surveyed in the companion volume Comprehensive Organometallic Chemistry and so only apposite references will be included here.32... 

This article sununarizes some of the recent developments in alkaline earth organometalhc chemistry. Several excellent review articles are available for more detailed discussions on the subject areas. It is important to note that radium, the heaviest alkaline earth metal, is radioactive and no organometallic compounds have been reported. 

With <7-bonded organometallic compounds of the heavy alkaline earth metals stiU hmited to calcium, the expansion of the library of such compounds to the heavier metals was... 

B. J. Wakefield, Compounds of the alkali and alkaline earth metals in organic synthesis. Comprehensive Organometallic Chemistry, Pergamon Press, Oxford, 1982, Chap. 44. 

This chapter will cover the monovalent neutral polyatomic derivatives of the alkaline earth elements Be, Mg, Ca, Sr, Ba, and Ra. The alkaline earth metals are naturally divalent in the solid state. Well-known examples of alkaline earth compounds are the widely used Grignard reagents, which have an empirical formula R—Mg—X (R is an alkyl group and X is a halogen) [1]. More recently, the Hanusa group at Vanderbilt has explored the organometallic chemistry of divalent Ca, Sr, and Ba derivatives [8]. In contrast to this normal chemistry, the monovalent derivatives such as CaOH are unstable in the solid state because they readily disproportionate ... 

These differences in reactivity of the various organometallic compounds also appear on their hydrolysis, which affords a hydrocarbon and a metal hydroxide. For instance, alkyl derivatives of alkali or alkaline-earth metals undergo rapid and violent reaction with water, whereas the quite weakly polar alkylsilicons do not react at all under these conditions. 

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