Of organometallic species

Prange A, Jantzen E (1995) Determination of organometallic species using GC-ICP-MS. Journal of Analytical Atomic Spectrometry, 10 105-109. 

The first series of soluble oligo(para-phenylene)s OPVs (20) were generated by Kern and Wirth 1331 and shortly thereafter by Heitz and Ulrich [34]. They introduced alkyl substituents (methyls) in each repeat unit and synthesized oligomers (20) up to the hexamer. Various synthetic methods, like copper-catalyzed Ullmann coupling, copper-catalyzed condensation of lithium aryls, and twofold additon of organometallic species to cyclohexan-l,4-dione, have been investigated. 

The authors developed two general methodologies for the synthesis of these monodisperse, defined oligomers. They can be built up stepwise, e. g. via additon of organometallic species to cyclohexan-1,4-dione, followed by aromatization to the oligoarylene (e.g. for 21). 

Nolan, M. Porchia, G. Sishta, T. J. Marks in Energetics of Organometallic Species, J. A. Martinho Simoes (ed.), Kluwer Dordrecht, 1992, pp 35-51. 

Two challenging, but very difficult tasks have been tackled mainly or increasingly during the last two decades the certification of organometallic species and valency states of elements (see Section 3.3), and organic compounds (see Section 3.4). But doubtless this was just the beginning and a wealth of work waits in the future to serve all needs of the analytical community (Quevauviller and Maier 1999)-... 

With the exception of GC-MIP-AES there are no commercial instruments available for speciation analysis of organometallic species. Recently, a prototype automated speciation analyser (ASA) for practical applications was described [544,545], which consists of a P T system (or focused microwave-assisted extraction), multicapillary GC (MC-GC), MIP and plasma emission detection (PED). MCGC-MIP-PED provides short analysis times ([Pg.676]

It is not our intention in this section to provide a comprehensive review of flash photolysis of organometallic species rather, we summarize some key experiments which establish the timescales of different types of reactions. Understandably, much more work has been done on the flash photolysis of metal carbonyls in solution than in the gas phase, and so we begin with solution experiments. 

The application of newer methods to studies of gas phase organometallic reactions will lead to the development of routine techniques for determination of the thermochemistry of organometallic species. The examples discussed above demonstrate that an analysis of kinetic energy release distributions for exothermic reactions yields accurate metal ligand bond dissociation energies. This can be extended to include neutrals as well as ions. For example, reaction 15 has been used to determine accurate bond dissociation energies for Co-H and C0-CH3 (57). 

To date, most of the photochemical data available for transition metal complexes comes from condensed phase studies (1). Recently, the primary photochemistry of a few model transition metal carbonyl complexes has been investigated in gas phase (5.). Studies to date indicate that there are many differences between the reactivity of organometallic species in gas phase (5.6) as conq>ared with matrix (7-10) or solution (11-17) environments. In most cases studied, photoexcitation of isolated transition metal... 

The application of these techniques has led to the discovery of a number of organometallic species of arsenic, tin, and antimony in the marine environment. Germanium has not been observed to form organometallic compounds in nature. Some aspects of the geochemical cycles of these elements which have been elucidated by the use of these methods are discussed. 

A considerable number of organometallic species of germanium, tin and lead have been detected in the natural environment. A number of these are nonmethyl compounds which have entered the environment after manufacture and use (e.g. butyltin and phenyltin compounds by diffusion from antifouling paints on boats, and ethylleads from leaded gasoline). Only a few methyl compounds are now manufactured and used (e.g. some methyltin compounds are used as oxide film precursors on glass)1. 

Carbometallation of allenes with alkenylruthenium complexes has been reported in a stoichiometric process for the preparation of 2-alkenylallylruthenium complexes.97 Such types of organometallic species have not been well explored, and could give rise to new applications in transition metal catalysis. 

M. E. Minas da Piedade, J. A. Martinho Simoes. Energetics of Organometallic Species The Entropic Factor. J. Organometal. Chem. 1996, 518, 167-180. 

Coordination of organometallic species has been used in studies of stereocontrol of the addition. These stereocontrolled addition reactions possess considerable preparative potential as outlined in the following examples. Addition of Grignard reagents to chiral aldoxime ethers such as 100 (equation 69) was found to proceed with a substantial stereoselectivity. ... 

The nucleophilic attack of organometallic species occurs with cleavage of the N—S bond and eventual formation of an a-diketone. This reaction has been shown to proceed through an unsym-metrical diimine (17) (Scheme 2) <90JHC1861>. The 4-unsubstituted series (18) can be functionalized in this way. The diimine product of ring opening (19) can add a nucleophile at carbon (20) and then be recyclized to a 3,4-disubstituted 1,2,5-thiadiazole (21) (Scheme 3) <86H1131>. 

The electrophilic amination reaction of organometallic species using mono-, di- and trihaloamines has attracted a lot of attention for the synthesis of amines. Only a few cases have been reported using alkylchloroamines as precursors for the synthesis of tertiary amines One example is the reaction of functionalized aryhnagnesium compounds with benzyl-V-chloroamines 252 providing polyfunctional tertiary amines 253 (equation 164) °. The procedure was also applied for the preparation of chiral V-chloro-amines with retention of chirahty at the a-carbon. However, the amination process is limited to benzyl-V-chloroamines. 

The present discussion of isomerism in coordination compounds is not, nor was it intended to be, comprehensive and exhaustive. The examples considered are an eclectic selection, and many important systems may have been neglected through ignorance. An obvious omission is any detailed consideration of polynuclear complexes139,256"259 and it is, of course, a quite arbitrary decision not to include any consideration of organometallic species. Other neglected issues, such as the development of a truly comprehensive system of stereochemical nomenclature, are perhaps not yet capable of solution. Nevertheless, it is to be hoped that the principal factors to be considered... 

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