Applications of the method of continuous variations (MCV or the Method of Job) to problems of interest to organometallic chemists are described. MCV provides qualitative and quantitative insights into the stoichiometries underlying association of m molecules of A and n molecules of B to form AmBn . Applications to complex ensembles probe associations that form metal clusters and aggregates. Job plots in which reaction rates are monitored provide relative stoichiometries in rate-limiting transition structures. In a specialized variant, ligand- or solvent-dependent reaction rates are dissected into contributions in both the ground states and transition states, which affords insights into the full reaction coordinate from a single Job plot. Gaps in the literature are identified and critiqued.

/pdf/method-of-continuous-variations-applications-of-job-plots-to-3nx4ynwsfs.pdf

Method of Continuous Variations: Applications of Job Plots to the Study of Molecular Associations in Organometallic Chemistry[**]

Multinuclear studies of aluminium compounds

The reactivity of allylic organometallic compounds of lithium, sodium, magnesium, zinc, cadmium and aluminium: Recent advances

The synthesis and subsequent reduction of the arylboron dihalides 2,6-Mes2C6H3BX2 (X = Cl (1); Br (2)) and 2,6-Trip2C6H3BBr2 (3) (Mes = 2,4,6-Me3C6H2- and Trip = 2,4,6-i-Pr3C6H2-) are described. Treatment of 2 with lithium metal in diethyl ether gave the novel lithium 9-borafluorenyl compounds 4 and 5 (see Scheme 1) in which the boranediyl intermediate has inserted into an o-Me-ring C−C σ-bond to form a borafluorenyl structure incorporating boron in a delocalized five-membered ring. Boranediyl insertion into C−C σ-bonds, as distinct from boranediyl induced rearrangements involving CC cleavage in delocalized aromatic substrates, is unknown. The main difference between the structures of these products is that 5 is dimerized as a consequence of the reduction in the number of solvating ethers. Reduction of 2 with KC8 led to the isolation of the 9-borafluorenyl “ate” compounds 6 and 7. These products also result from C−C bond insertion by boron as seen in 4 and 5. However, the delocalization is not observed ow...

Isolation and Reduction of Sterically Encumbered Arylboron Dihalides: Novel Boranediyl Insertion into C−C σ-Bonds

There are basically two kinds of hetero atoms in organic molecules: one kind confers electrophilic character upon the carbon atom to which it is bound, and the other kind turns it into a nucleophilic site. The development of methods permitting transitions between the two resulting categories of reagents has become an important task of modern organic synthesis. The scope of such umpolung of the reactivity of functional groups is discussed for the case of amines as an example. A method of preparing masked α-secondary amino carbanions consists in nitrosation of the secondary amine, followed by metalation of the resulting nitrosamine α-to the nitrogen, reaction with electrophiles, and subsequent denitrosation. Many examples are given for each of these steps which illustrate the wide scope of the overall synthetic operation (electrophilic substitution at the α-C atom of the secondary amine). Preliminary applications and a method for avoiding the handling of nitrosamines are presented, and the report concludes with a brief account of the significance of nitrosamines in the study of carcinogenesis and mutagenesis.

John J. Eisch

Papers

Proposed radical pathway for the additon of allyl grignard reagents to conjugated anils

Intramolecular coordinative assistance in the addition of Grignard reagents to unconjugated carbon-carbon unsaturation

Bora-aromatic systems I. Competition between haloboration and phenylboration in the attempted synthesis of triphenylboracyclopropene☆☆☆

Nickel-catalyzed hydralumination of alkynes and the nickel effect in the ziegler dimerization of ethylene

The question of allylic rearrangement in the reactions of tribenzylaluminum