Boron stabilized, with

Small amounts of boron stabilize a W(,Fe7-type /z-phase Hf 4,Alo 5oBQQ5 with B atoms occupying interstitial positions. In the cast alloys of Mo 4 5Re,5 5B 2 2... 

As described in previous sections (Sections VI and VII), macromolecular design of polymer/salt hybrids with a highly dissociable lithium borate unit proved to be a valuable approach for single-ion conductive polymers. To further improve the degree of lithium salt dissociation, we have designed a polymer/salt hybrid bearing the boron-stabilized imidoanion (BSI)38 (Fig. 10). 

A synthesis of comblike organoboron polymer/boron stabilized imidoanion hybrids was examined via reactions of poly(organoboron halides) with 1-hexylamine and oligo(ethylene oxide) monomethyl ether and subsequent neutralization with lithium hydride (scheme 8). The obtained polymers (10) were amorphous soft solids soluble in common organic solvents such as methanol, THF, and chloroform. In the nB-NMR spectra (Fig. 11), neutralization of the iminoborane unit with lithium hydride... 

In the same way as for Ceo and C70 fullerenes, boron clusters with magic numbers B5+ and Bi3+ appear as prominent peaks in mass spectra. These boron clusters were calculated for various geometries by several authors and were considered to present 3D aromatic stabilization.297-299... 

In the Suzuki strategy 138 was treated with trityl chloride to afford amine 139 in 84% yield (Scheme 4.29) (Todo et al., 2000). Metal-halogen exchange of 5-bromoisoindoline 139 was achieved using w-butyl lithium at — 65°C to deliver an intermediate organolithium species that was trapped with triisopropylborate to afford the boronic acid upon work-up. Further treatment of the boronic acid with diethanolamine gave diethanolamine boronic ester 140 (Hayashi et al., 2002). Presumably, the diethanolamine boronic ester was formed for stability reasons, as a given diethanolamine boronic ester tends to be less... 

If the pKa of the corresponding acid R1 - H from the stabilized carbanion is smaller than 35, the migration of R1 fails in (dichloromethyl)borate complexes. Failure to convert pinanediol [(phenylthio)methyl]boronate to an a-chloro boronic ester has been reported15. Reaction of (dichloromethyl)lithium with an acetylenic boronic ester resulted in loss of the acetylenic group to form the (dichloromethyl)boronate, and various attempts to react (dichloromethyl)boronic esters with lithium enolates have failed17. Dissociation of the carbanion is suspected as the cause, but in most cases the products have not been rigorously identified. 

In agreement with these findings aminoborylene complexes of the type [p-BR2 (p5-C5H5)Mn(CO)2 2] (1) proved to be inert toward air and water and to undergo nucleophilic substitutions at the boron center with retention of the electronically stabilized Mn2B-skeleton vide supra). 

Alkyl radicals stabilized with boron atom are easily generated and undergo addition and coupling reactions. Such cr-boryl radicals were generated in situ by treatment of a-chloroalkylboronic esters with CrCl2 (Equation (188))706 or with radical initiators such as AIBN (Equation (189)).707... 

The requirement for an initial dissociation step implies that halogen redistribution rates should parallel the ease of dissociation of one of the halogens, and this expectation is confirmed in fluorine - heavier halogen redistributions where the rates change from slow to very fast over the series Cl, Br, I as the B—X bond becomes weaker. Rates should also be related to stabilization of the residual boron trihalide formed on dissociation. The boron trihalide with the greatest number... 

Diboryl compounds do not yield aldehydes with alkaline hydrogen peroxide. Instead there is r d hydrolysis, presumably via a boron-stabilized carbanion (see Volume 1, Ch ter 2.6) which is protonated and then oxidized to the alcohol (equation 16). ... 

Coupling of silyl enol ethers or boron enolates with Co2(CO)6-stabilized carbocations, generated via Lewis acid treatment of the appropriate propargyl ethers or aldehydes (aldol reaction), via the Nicholas reaction has been used to obtain large, highly strained, ring ketones. 

There is a marked increase in stability, with respect to formation of boron trifluoride, along the series CF3BF2 CF2=CFBF2 < C6F5BF2 [71, 77, 78] and this can be related to partial co-ordinative saturation of boron. 

Because of its stability with regard to disproportionation, t-C4H9PF2 can be employed as a useful P(III) ligand, and a variety of complexes with transition metals, both zerovalent and in positive oxidation states, as well as those with boron acceptors, have been prepared. The preparation of a representative complex is described below. 

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