4-methyl- tetraphenylborate

A quantity of sodium tetraphenylborate(l —) (548 mg, 1.6 mmol) and methanol (10 mL) are placed in a Schlenk flask (20 mL) and stirred until all the solid has dissolved. Solution A, prepared as described in Section A, is treated first with lmL of methyl acrylate and then with the tetraphenylborate(l —) solution. A nitrogen flow is passed through a side arm to provide an intert atmosphere. 

Trimethylsilylimino) (trimethylsilyl) [tris(dimethylamino)phosphoranylidene] methyl phosphine (64), produced by the reaction of [(dichlorophosphanyl)methyl]tris (dimethylamino)phosphonium tetraphenylborate with sodium bis(trimethylsilyl)amide,... 

In comparison, the l,3-dialkylimidazolium-2-carboxylate isolated by Tommasi et al. [27, 40] was revealed to be a more versatile catalyst that allowed the synthesis of benzoylacetic acid from benzophenone and C02 in good yield and under mild conditions (isolated yield 81%). The presence of tetrafluoroborate- or tetraphenyl-borate sodium salts in the reaction was essential, as this allowed the formation of the related 1,3-dialkylimidazolium tetrafluoroborate or tetraphenylborate and the concomitant quantitative trans-carboxylation to sodium benzoylacetate. Likewise, compounds such as acetone, cyclohexanone, and phenylacetonitrile could also be converted with this system to afford the corresponding carboxylate salts (methyl a-cyanophenylacetate) (Scheme 5.8). Following the same general procedure, acetone was carboxylated, being simultaneously the cosolvent and reagent. 

Dimethyl Phenyl Telluronium Tetraphenylborate1 0.46 g (2 mmol) of dimethyl telluronium dichloride are dissolved in 30 ml of absolute methanol and a solution of 1.7 g (5 mmol) of sodium tetraphenylborate in 30 ml of methanol is added dropwise with stirring at 20°. Stirring is continued for 2 h, the mixture is filtered, and the solid is recrystallized from ethyl methyl ketone yield 0,81 g (65%) decomposes above 200°. 

Methyl-l-phenyl-tellurolanium Tetraphenylborate A mixture of 4.52 g (10 mmol) 2-methyl-telIuroIane-... 

HGURE 8.1. Formal potentials of redox species in W, NB and DCE versus NHE. Abbreviations ZnTMPyP = zinc tetra-7V-methyl-4-pyridium porphyrin, DcMFc = decamethylfetrocene, TCNQ = 7,7,8,8-tetracyanoquinodimethane, DiMFc = dimethylferrocene, Fc = ferrocene, RuTPP(py)2 = bisfpyridine) meso-tetraphenylporphyrinato ruthenium(II), SnPc2 = tin(IV) diphthalocyanine, LuPc2 = lutetium(in) di]dithalo-cyanine, DiFcET = diferrocenylethane, TAA = tris(4-methoxyphenyl)amine, TPB = tetraphenylborate, TBrPA = tris(4-bromophenyl)amine, TCIPB = tetrakis(4-chlorophenyl)borate. The data is from Ref. [26], except where otherwise noted Ref. [6], Ref. [29], Ref. [30], Ref. [31], Ref. [32]. Reprinted from Ref. [28], with permission from the Polarographic Society of Japan. 

The same silyl ion also was examined in condensed phases by Lambert with his perfluorinated tetraphenylborate counterion [41]. While the solid state structure of this complex is not known, its Si shift is 107.6 ppm, close to the Reed s value. As the silicon atom might be coordinated to one or to two fluorine atoms [42], we calculated model complexes of SiMe3 with methyl fluoride and with cis-difluorethene. The smaller fluorine atoms are able to approach closer to silicon than bromine (Fig. 16), but the shift in electron density towards the cationic moiety is negligible. 

Tellurolanium 2-Methyl-l-phenyl-(Tetraphenylborate) E12b, 691 (R2TeI2 +- BAr4)... 

To l-methyl-3-ethyIimidazolium bromide (0.1 g) in dry methanol (5 ml) is added silver tetraphenylborate (0.2 g) in methanol (15 ml). The mixture is refluxed (2h) and filtered from silver bromide, and then the solvent is evaporated to give the tetraphenylborate salt (36%), m.p. 140°C. Similarly prepared using silver perchlorate in dry acetone is l-cthyl-3-methylimidazolium perchlorate (83%) as an oily liquid. 

Figure 5. Intimate donor-acceptor orientation in the inner-sphere CT salts of (A) quinolinium with tetracarbonylcobaltate [118], (B) A-methyl-4-cyanopyridinium with tetracarbonylcobaltate [118], (C) A-methyl-3-cyanopyridinium with tetraphenylborate [65], and (D) iV-methyl-4-cyanopyr-idinium with TpMo(CO)j [127].

Dimethyl and methyl phenyl 4,4-dimethyl-2,6-dioxocyclohexylidene tellurium compounds transferred a methyl group to triethylamine, triphenylphosphane, tris[di-methylamino]phosphane, and triphenylarsane. The methyl onium cations were isolated as tetraphenylborates. The alkylidene organo telluronium intermediate was identified by P-NMR spectroscopy in the reaction of the ylide with tris[dimethylamino]phosphanek... 

Various aromatic amines, phenols, and compounds containing active methylene groups can be titrated with arenediazonium salts, from which 4-bromo-l-naphthale-nediazonium chloride seems to be the most widely applicable titrant. Compounds that react slowly with arenediazonium salts can be determined by back-titration when the excess of arenediazonium salt is back-titrated with either sodium tetraphenylborate or 2,4-diaminotoluene. Indirect determination is useful for secondary amines, which react with arenediazonium ions to form triazenes. The determination of diazonium salts of ampholytic character is based on the reaction of these salts with l-phenyl-3-methyl-5-pyrazolone, the excess of which is titrated with 4-bromo-l-naphthalenediazonium chloride solution. 

PjBORhSjCttH, Rhodium(III), [[2-[(di-phenylphosphino)methyl]-2-methyl-l,3-propanediyl]bis(diphenylphosphine)]-(dithiocarbonato)-, tetraphenylborate (1-), 27 287... 

---