Organometallic compound other compounds

Today the term anionic polymerisation is used to embrace a variety of mechanisms initiated by anionic catalysts and it is now common to use it for all polymerisations initiated by organometallic compounds (other than those that also involve transition metal compounds). Anionic polymerisation does not necessarily imply the presence of a free anion on the growing polymer chain. 

Table 2. Synthesis by recoil methods a partial list of radioactive organometallic compounds, other than the starting material, synthesized by recoil methods...

Homogeneity was, and still is, determined for elements in RMs by various modes of e.g. NAA, XRF, AAS, ICP-AES, ICP-MS and electrochemical methods after decomposition see Section 3.2 and for organometallic and other compounds by combination of chromatographic techniques with these methods, see Section 3.3. 

For certain types of complexes (particularly organometallic compounds) other rules are needed, but the majority of complexes can be correctly named using the short list of rules just given. 

The first attempts to employ organometallic compounds other than Grignard reagents for the glycosylation of hydrocarbons have been those of Hurd and Holysz. These investigators studied the reactions of a... 

Optically active ochotensanes of structure (117) have been obtained from (+)-and (—)-/S-canadine methochloride (116 R = H) and iV-methylthalictricavine chloride (116 R = Me) by rearrangement with organometallic compounds, other products being the two Hofmann degradation products.122... 

Tel. 33-88-41-61-42, fax 33-88-61-20-85, e-mail rohmer frccsc21.bitnet Ab initio calculations for large organometallic and other compounds. FORTRAN programs designed for Cray supercomputers. 

Topic D3). will also form intercalation compounds. The inserted species may be alkali metals, or electron donor molecules such as amines or organometallic compounds. Sometimes compounds of definite composition may be formed, such as KC6 or C8Br, but in other cases intercalated phases... 

The HPLC analysis of a mixture of phenylchlorosilanes using gel permeation columns is described. The method is applicable to a variety of organometallics or other compounds that are sensitive to air and water. 

Ab initio calculations for large organometallic and other compounds. FORTRAN programs designed for Cray supercomputers. 

These warnings should not lead to the conclusion that the free radical cyclization (or ring-opening) tool must be avoided. Quite the contrary, the 5-hexenyl cyclization is certainly one of the best probes for the presence of alkyl free radical intermediates, but in dubious cases, as for instance those involving organometallic compounds, other probes are needed. 

Molecules in this category contain atoms other that carbon and hydrogen. The distinction is made between organic and organometallic compounds. 

The transmetallation of various organometallic compounds (Hg, Tl, Sn, B, Si, etc.) with Pd(II) generates the reactive cr-aryl, alkenyl, and alkyl Pd compounds. These carbopalladation products can be used without isolation for further reactions. Pd(II) and Hg(II) salts have similar reactivity toward alkenes and aromatic compounds, but Hg(II) salts form stable mercuration products with alkenes and aromatic rings. The mercuration products are isolated and handled easily. On the other hand, the corresponding palladation products are too reactive to be isolated. The stable mercuration products can be used for various reactions based on facile transmetallation with Pd(II) salts to generate the very reactive palladation products 399 and 400 in rim[364,365]. 

In Grignard reactions, Mg(0) metal reacts with organic halides of. sp carbons (alkyl halides) more easily than halides of sp carbons (aryl and alkenyl halides). On the other hand. Pd(0) complexes react more easily with halides of carbons. In other words, alkenyl and aryl halides undergo facile oxidative additions to Pd(0) to form complexes 1 which have a Pd—C tr-bond as an initial step. Then mainly two transformations of these intermediate complexes are possible insertion and transmetallation. Unsaturated compounds such as alkenes. conjugated dienes, alkynes, and CO insert into the Pd—C bond. The final step of the reactions is reductive elimination or elimination of /J-hydro-gen. At the same time, the Pd(0) catalytic species is regenerated to start a new catalytic cycle. The transmetallation takes place with organometallic compounds of Li, Mg, Zn, B, Al, Sn, Si, Hg, etc., and the reaction terminates by reductive elimination. 

Formation of ketones. Ketones can be prepared by the carbonylation of halides and pseudo-halides in the presence of various organometallic compounds of Zn, B, Al, Sn, Si, and Hg, and other carbon nucleophiles, which attack acylpalladium intermediates (transmetallation and reductive elimination). 

The stereochemistry of the Pd-catalyzed allylation of nucleophiles has been studied extensively[5,l8-20]. In the first step, 7r-allylpalladium complex formation by the attack of Pd(0) on an allylic part proceeds by inversion (anti attack). Then subsequent reaction of soft carbon nucleophiles, N- and 0-nucleophiles proceeds by inversion to give 1. Thus overall retention is observed. On the other hand, the reaction of hard carbon nucleophiles of organometallic compounds proceeds via transmetallation, which affords 2 by retention, and reductive elimination affords the final product 3. Thus the overall inversion is observed in this case[21,22]. 

The properties of organometallic compounds are much different from those of the other classes we have studied to this point Most important many organometallic com pounds are powerful sources of nucleophilic carbon something that makes them espe cially valuable to the synthetic organic chemist For example the preparation of alkynes by the reaction of sodium acetylide with alkyl halides (Section 9 6) depends on the presence of a negatively charged nucleophilic carbon m acetylide ion... 

The fundamental Ziegler-Natta recipe consists of two components the halide or some other compound of a transition metal from among the group IVB to VIIIB elements and an organometallic compound of a representative metal from groups lA to IIIA. Some of the transition metal compounds that have been... 

The bimetallic mechanism is illustrated in Fig. 7.13b the bimetallic active center is the distinguishing feature of this mechanism. The precise distribution of halides and alkyls is not spelled out because of the exchanges described by reaction (7.Q). An alkyl bridge is assumed based on observations of other organometallic compounds. The pi coordination of the olefin with the titanium is followed by insertion of the monomer into the bridge to propagate the reaction. 

This index contains over 40,000 individual entries to the 6200 text pages of Volumes 1-7. The index mainly covers general classes of heterocyclic compound and specific heterocyclic compounds, but also included are natural products, other organic and organometallic compounds where their synthesis or use involves heterocyclic compounds, types of reaction, named reactions, spectroscopic techniques and topics involving heterocyclic compounds. 

Although inhibitors are deliberately added to the silicone formulation to control cure rate, unwanted cure inhibition can be caused by other species that react to form strong complexes with the platinum catalyst. Most notable of these undesired inhibitors include organotin and other organometallic compounds, sulfur, polysulfides, polysulfones or other sulfur-containing materials, amines, urethanes or amine-containing materials, unsaturated hydrocarbons in plasticizers, and some solder flux residues. 

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. 

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... 

Organolithium reagents are also valuable in the synthesis of other organometallic compounds via... 

Other compounds containing Al-N or Ga-N bonds, including heterocyclic compounds and cluster organometallic compounds, are considered in section 7.3.6. 

Tin is unsurpassed by any other metal in the multiplicity of applications of its organometallic compounds. The first organotin compound was made in 1849 but large-scale applications have developed only recently indeed, world production figures for organotin compounds increased more than 700-fold between 1950 and 1980 ... 

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