Basicity of organometallics

Three basic methods have been used for the preparation of organodihaloboranes, RBX2 (1) the direct interaction of hydrocarbons with haloboranes, (2) the reaction of organometallic derivatives with haloboranes, and (3) the halogenation of organoboranes. One of the most convenient laboratory procedures involves the reaction of tetraorganotin derivatives with trihaloboranes, BX3.1-8 This reaction works particularly well for the preparation of alkyldihaloboranes as outlined below. 

In previous chapters, we have presented a great deal of information about structure and bonding in coordination compounds. This chapter will be devoted to describing some of the important chemistry in the broad areas of organometallic complexes and those in which there are metal-metal bonds. The body of literature on each of these topics is enormous, so the coverage here will include basic concepts and a general survey. 

One of the several mechanisms for decarboxylation is the reverse of the familiar carboxylation reaction of organometallic compounds or carbanions. Many of the acids RCOOH that are readily decarboxylated in basic media are compounds for which the corresponding R( ) is a comparatively stable carbanion.405 The postulated intermediate has actually been trapped or diverted in a few cases as the product of an aldol condensation.406... 

The compounds of lithium and magnesium are the most important of the group IA and IIA organometallics from a synthetic perspective. The metals in these two groups are the most electropositive of the elements. The polarity of the metal-carbon bond is such as to place high electron density on carbon. This electronic distribution is responsible for the strong nucleophilicity and basicity of these compounds. 

The conjugate addition of organometallic reagents to a./i-unsaturated compounds is one of the basic methods in our repertoire for the construction of carbon-carbon bonds. These addition reactions have been used as key steps in the synthesis of numerous biologically active compounds, and show a broad scope due to the large variety of donor and acceptor compounds that can be employed. It is evident that a tremendous effort has been devoted over the last three decades to develop asymmetric variants of this reaction. ... 

The introduction of metals into plasma polymers has been the subject of some research during recent years. Basically, three methods have been used (a) Plasma polymerization of organometallic compounds [79,80], (b) Concomitant etching or sputtering of metals [81] and (c) Evaporation of metals into a [82] plasma polymerization system. Munro et aL [83, 84] incorporated mercury into... 

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