Alkali organometallic

The slow development of heavy alkali organometallic chemistry is due to high reactivity, as rationalized by the increase of polar character of the metal-ligand bond due to the reduced polarizing ability of the metals. The increase in ionic character on descending the group of alkali metals is clearly demonstrated by the increase in ionic radii with Li+(0.69A), Na+(0.97A), K+(1.33A), Rb+(1.47A), and Cs+(1.67A), resulting in a radius of Cs+ that is more than double of that of Li+. 

The flow of information on the highly reactive alkali organometallics in the 1990s is certainly closely connected to the wider availability of low temperature crystallography and advanced crystal mounting techniques,22 allowing the structural characterization of compounds previously deemed too reactive for investigation. 

The main reactions of alkali organometallics are metallation or deprotonation, reduction (vide supra), alkylation of transition-metal halides and addition on multiple bonds ... 

Metal exchange reactions have been used in the preparation of heavy alkali organometallics by reaction of alkali metal alkoxide or aryloxide with an organolithium reagent under precipitation of lithium alkoxide/aryloxide. For these reactions, careful ligand choice enables the separation of the two solid reaction products. Two variants of this reaction for alkaline-earth metal organometallics... 

Organometallics, such as dialkyl zinc or cadmium-alkyl or aryl lithium Alkali acetylides Diels-Alder Arndt-Eistert... 

In recent years this simple picture has been completely transformed and it is now recognized that the alkali metals have a rich and extremely varied coordination chemistry which frequently transcends even that of the transition metals. The efflorescence is due to several factors such as the emerging molecular chemistry of lithium in particular, the imaginative use of bulky ligands, the burgeoning numbers of metal amides, alkoxides, enolates and organometallic compounds, and the exploitation of multidentate... 

Similar structural diversity has been established for the heavier alkali metals also but it is unnecessary to deal with this in detail. The sUTictural chemistry of the organometallic compounds in particular, and of related complexes, has been well reviewed. 

Some structural aspects of the organometallic compounds of the alkali metals have already been briefly mentioned in Section 4.3.6. The diagonal relation of Li with Mg (p. 76), coupled with the known synthetic utility of Grignard reagents (pp. 132-5), suggests that Li, and perhaps the other alkali metals, might afford synthetically... 

Organometallic compounds of the alkali metals (particularly LiMe and LiBu") are valuable synthetic reagents and have been increasingly used in industrial and laboratory-scale organic syntheses during the past 20 y,(86,94,95) annual produc-... 

Organometallic reagents and alkali metal amides can react via a cyclic transition state (Section II, B, 5) beginning with electrophilic attack at the most basic ring-nitrogen. As a result, sodamide (in dimethylaniline, 145°, 2 hr) yields the 4-amino derivatives (40% yield S)) methyl- or phenyl-magnesium iodides give the 4-adduct quantitatively.s ... 

Otganocoppet diemistry remains a mainstay of organic syntliesis because of tlie range of copper-promoted ttansfotniations on offer and because it is often complementary to pailadium diemistry and alkali and alkaline eartli organometallic... 

Hexamethylphosphoric triamide (HMPT) is a high-boiling solvent particularly satisfactory for dissolving metals or organometallic compounds. It has been found to be an ideal solvent in which to conduct the reduction of a,jS-unsaturated ketones by alkali metals. 

Ge, P, As, Sb, and Bi, can also be prepared in this manner." Except for alkali metal alkyls and Grignard reagents, the reaction between RM and M X is the most conunon method for the preparation of organometallic compounds." ... 

Electronic Effects in Metallocenes and Certain Related Systems, 10, 79 Electronic Structure of Alkali Metal Adducts of Aromatic Hydrocarbons, 2, 115 Fast Exchange Reactions of Group I, II, and III Organometallic Compounds, 8,167 Fluorocarbon Derivatives of Metals, 1, 143 Heterocyclic Organoboranes, 2, 257... 

Substances which react with water to liberate flammable gas, e.g. carbides (liberate acetylene), alkali metals (hydrogen), organometallics (hydrocarbons - see Table 6.8), and where the heat of reaction is sufficient to ignite the gas. Thus metals which are less electronegative than hydrogen (see Table 6.10) will displace this element from water or alcohols, albeit at different rates. 

Smith, David J., Organometallic Compounds of the Heavier Alkali Metals. 43 267... 

Simple transition metal halides react cleanly with alkali metal boratabenzenes. In this way sandwich-type complexes 32 of V (27), Cr (64), Fe (58), Ru (61), and Os (61) have been made. The corresponding nickel complexes seem to be nonexistent, quite in contrast to NiCp2 in attempted preparations, mixtures of diamagnetic C—C linked dimers were obtained (29). In the manganese case, high sensitivity to air and water has precluded preparative success until now. Some organometallic halides have added further variations to the main theme. The complexes 33 of Rh and 34 of Pt were obtained from [(COD)RhCl]2 and [Me3PtI]4, respectively (61). 

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