Group I Organometallic Compounds

Doubly labeled (13C —6Li) butyllithium, for example, displays a quintet splitting with JCtT.j = 7.8 Hz at — 90CC in tetrahydrofuran [478], Following the (2nl + 1) multiplicity rule, the number of lithium nuclei eLi with 1 = 1 coupling to each carbon is 2. Thus, butyllithium occurs as a dimer, similarly to cyclopropyl-, vinyl- and phenyllithium [478]. 

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Before we describe the applications of organometallic reagents to organic synthesis, let us examine their preparation. Organolithium compounds and other Group I organometallic compounds are prepared by the reaction of an alkyl halide with the appropriate metal. 

Coupling Reactions with Group I Organometallic Compounds... 

The main purpose of these final comments is to show a few general trends in the thermochemistry of Group 14 organometallic compounds, helped by some (hopefully) reliable values. And one of the trends is revealed by a rather usual plot1,2, in which the mean bond dissociation enthalpies of the species MR4 (i.e. one-fourth of the enthalpy required to break all the M—R bonds) are represented as a function of the enthalpy of formation of M in the gaseous state. As observed in Figure 4, for R = H and Me, D(M—H) and D(M—Me) increase with the enthalpy of formation (or sublimation) of M. It is noted, on the other hand, that the differences D(M—H) — D(M—Me) vary from 47.7 kJmol-1... 

Organolithium compounds form a unique class of organometallic compounds with stability, solubility, and activity characteristics intermediate between those of the other Group I and the Group II organometallic compounds. 

Nakanishi, K., Mizuno, K., and Otsuji, Y, Intramolecular [2 -I- 2 ] photocycloaddition of group 14 organometallic compounds bearing a styrene chromophore a route to sila- and germa-cyclo-phanes and spiro compounds, /. Chem. Soc., Perkin Trans. 1, 3362, 1990. 

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... 

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