Radicals boron-containing

Benzyl radicals with boron containing substituents at C(7) ... 

CC126). X-ray crystal structures of the derivatives 160a,b were obtained, and using cyclic voltammetry it was shown that they can be reduced to borataverdazyl radical anions, the first-ever boron-containing verdazyl radicals. 

Compounds containing fluorine and chlorine are also donors to BF3. Aqueous fluoroboric acid and the tetrafluoroborates of metals, nonmetals, and organic radicals represent a large class of compounds in which the fluoride ion is coordinating with trifluoroborane. Representative examples of these compounds are given in Table 5. Coordination compounds of boron trifluoride with the chlorides of sodium, aluminum, iron, copper, 2inc, tin, and lead have been indicated (53) they are probably chlorotrifluoroborates. 

The spectra of a number of triatomic radicals with 15 valence electrons are now known for elements of the first period they are B02, N3, and NCO. In addition, the isoelectronic ions C02+ and N20+ have been investigated. The spectrum of B02 was observed by Johns41 in the flash photolysis of a mixture of BCI3 and 02, but later was found to be identical to the green bands observed in most flames and arcs containing boron.42 Isotope shifts (B1X-B10) and alternate missing lines in the spectrum immediately identify the carrier as... 

EPR experiments on carbon-centred radicals with either a- or /J-boronic ester substituents have been reported.168 While the a-substituted radicals were modestly thermodynamically stable, the /J-substituted radicals underwent easy /J-climination. An EPR experiment on the photo-oxidation of phenolic compounds containing at least one free ortho position has indicated the formation of persistent secondary radicals derived from dimerization or polymerization from C-0 coupling.169 The structure of the succinimidyl radical has been re-examined using density functional theory with a variety of basis sets. The electronic ground state was found to be of cr-symmetry allowing for facile -scission. These conclusions were also predicted using MP2 but... 

The synthesis of metal graphite compounds is carried out by the reduction of layer graphite compounds and metal chlorides by using different reducing agents such as, for instance, solutions of aromatic anion radicals in THF, metallic sodium in liquid ammonia, complex boron and aluminum hydrides, and vapor or liquid potassium. As a result, the complex compounds containing one (Sn, Co, Mn, Cr, Mo, W, Pd) and two (Fe-Mo, Fe-W, or Mo W) metals were synthesized. 

Taylor and cowoikers have studied the intramolecular capture of radical cations from the thallium trifluoroacetate oxidation of arylalkanoic acids and arylalkanols. For example, 3-(3,4-dimethoxyphe-nyl)propionic acid (43) on treatment with thallium trifluoroacetale in trifluoroacetic acid containing a small amount of boron trifluoride etherate fw a few seconds gave the oxidized products (44-46 Schenne... 

While plasma-enhanced methods are very usefiil to lower the substrate temperature, the as-deposited films are typically less conformal and often contain more surface impurities than competing methods. In this method, reactive radicals, ions, and atoms/molecules are formed in the gas phase that interact with the relatively low-temperature substrate to generate a film. Some of the more recent applications for plasma CVD include growth of cubic boron nitride (c-BN) thin films. 

Schuster and co-workers discovered that 1,4-dicyanonaphthalene solutions containing an alkyltriphenylborate salt, when irradiated, yield one-eleetron oxidation of the alkyltriphenylborate leading to carbon-boron bond cleavage and formation of free alkyl radicals [23]. In Gottschalk s hands [24, 25], it was shown that ionic salt pairs formed from cyanine dyes and alkyltriphenylborates (Figure 1) could be used as photoinitiators [26] that were active in the visible region of the spectrum. 

Nelson and Gordy (7) were successful in producing trapped BFg radicals by gamma irradiation of solid xenon which contained small concentrations of BFg. From observations on the electron-spln-resonance spectra of these radicals, a bond angle of 112 for BFg was derived by these workers to account for the hybridization of the o-bondlng orbitals of the boron atom. We adopt their... 

The codeposition of elements, such as phosphorus or boron, by direct interaction of the reducing agent with the catalytic surface was examined by some authors however, the interpretations are not completely satisfying. An indirect mechanism for hypophosphite reduction was proposed by Zeller and Landau.23 In this approach formation of phosphine as an intermediate and a direct interaction with radicals such as hydrogen atom H, hydride H , or NiOH was suggested.5, 12 24 26 However, the possible direct reduction of phosphite to phosphorous must also be considered. In favor of this hypothesis, there is the electrodeposition of NiP alloys from solutions containing Ni2+ and phosphite. The interaction of Ni2+ with the phosphite ions produces, at high pH, nickel phosphate precipitate when nickel ions are not adequately complexed. 

Such a mechanism was unlikely as addition of an external trap, 1,1-diphenylethylene, had no effect on the course of the arylation of p-ketoesters.i l A second approach involved the use of an internal trapping system which had been successfully used in the study of the radical reactions of arenediazonium salts.The internal trap containing reagent, ( rf/io-allyloxyphenyl)lead triacetate (94), can be easily prepared from the corresponding boronic acid. 2 Reaction with various types of nucleophiles, such as ethyl 2-oxocyclopentanecarboxylate (86), mesitol (36), the sodium salt of nitropropane, iodide and azide always afforded the C-arylation products in high yield. No trace of the 3-substituted dihydrobenzofurans, expected in a mechanism involving the intermediacy of free radicals, could be detected. 

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