Carbon bridge bonded

FIGURE 6 13 Mechanism of bromohydrin formation from cyclopentene A bridged bromonium ion is formed and is attacked by a water molecule from the side opposite the carbon-bromine bond The bromine and the hydroxyl group are trans to each other in the product... 

Perform an optimization of these two derivatives at the PM3 or RHF/STO-3G level in order to discern which is the more favorable isomer (the latter is a very long job). What are the most dramatic structural features that characterize these two isomers Do the bridging carbons remain bonded in the derivative ... 

Studies of the bonding of carbon monoxide to the metal surfaces produced structures in which the carbon atom is linked to one, two, or three metal atoms. The existence of bonds to two or three atoms (bridged bonds) has been questioned on the basis of theoretical calculations. None of these bondings, however, clarify the mechanism to any extent. 

With regard to the composition of the electrical effect, examination of the p values reported in Table XVII shows that in six of the sets which gave significant correlation, the localized effect is predominant (in these sets, either Pr < 50 or / is not significant). Thus it would appear that in so far as substituent effects are concerned, there are two major classes of electrophilic addition to the carbon-carbon double bond predominance of the localized effect or predominance of the delocalized effect. This behavior may well be accounted for in terms of the reaction mechanism. The rate-determining step in the electrophilic addition reaction is believed to be the formation of an intermediate which may be either bridged or a free carbonium ion. 

One-electron oxidation of the vinylidene complex transforms it from an Fe=C axially symmetric Fe(ll) carbene to an Fe(lll) complex where the vinylidene carbon bridges between iron and a pyrrole nitrogen. Cobalt and nickel porphyrin carbene complexes adopt this latter structure, with the carbene fragment formally inserted into the metal-nitrogen bond. The difference between the two types of metalloporphyrin carbene, and the conversion of one type to the other by oxidation in the case of iron, has been considered in a theoretical study. The comparison is especially interesting for the iron(ll) and cobalt(lll) carbene complexes Fe(Por)CR2 and Co(Por)(CR2) which both contain metal centers yet adopt... 

Alternatively, the (2 + 4)-tropilidene endoperoxide, which is the major product in the singlet oxygenation of cycloheptatriene 30 a) affords on diimide reduction the desired bicyclic peroxide 20. The double bond in the two-carbon bridge is reduced selectively, but on exhaustive treatment with excess diimide, the fully saturated substance is obtained. A number of substituted derivatives have been prepared in this way30). 

Fig. 3 Chemistry of site-specific PEGylation developed by Brocchini et al. [5, 6]. After cleavage of the native disulfide bond between two cysteine thiols by reduction, the free cysteines are reacted with an a, (3-unsaturated PEG derivative to produce a PEG conjugate via a three-carbon bridge...

With less polar solvents and more basic allyl anions the compounds are present as ion pairs. The carbon-metal bond with the alkali and alkaline earth metals are known to have high ionic character. The allyl compounds behave accordingly as salts. The structures of allyl compounds of the alkali and alkaline earth metals are of two fundamental types, a 41 (or metal cation is associated closely with a single terminal allylic carbon, and the rf 1 (or ji) type, 15, in which the cation bridges the two terminal allylic positions. 

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