Tetraphenylborate salts

In the Me2dtc complex, a unique, 15-line, epr spectrum was reported (69) that was peculiar only to the tetraphenylborate salt. This suggests a V-V interaction in the lattice. Electrochemical studies on these [CpjVLJ complexes (L = dithiocarboxylato ligand) shows two well defined, polarographic, reduction waves, and, for the process at most positive potential, the reversible formation of a V(III) species was postulated (72-74). 

Azoniaspiro[4.8]tridecane 129 was formed from the substituted triazacyclononane 128 (X = OMe) on standing in methanol for ten days (Scheme 15) <2000AJC791 >. It was precipitated as the tetraphenylborate salt 130 (X = BPli, ) since attempts to isolate the methoxide derivative by evaporation of the solvent led to elimination reactions yielding a mixture of triazacyclononane 131 and allene 132 in the ratio of 1 10. Re-dissolution of these allows further hydro-amination reactions to occur. Precipitation and analysis of their tetraphenylborate salts suggested the products to be 130-132 in a ratio of 1 8 1. Owing to their chemical similarities these components were not isolated. 

Phosphorus, arsenic, and antimony donor ligands. A general synthesis has been reported for trialkyl phosphite complexes of noble metals, including [RuLeJ, [RuXLsl, and [RuHLs]+ [L = P(OMe)3 or P(OEt)3 X = Cl or Br]. The complexes were isolated as their tetraphenylborate salts from reaction of the phosphite with methanolic solutions of suitable labile olefin... 

Reduction of the phosphine oxides to the phosphines may be performed in a procedure similar to the preparation of IV or more conveniently by refluxing 5 min in benzene with Si2Cl6 (II). For small quantities the tetraphenylborate salt of the phosphine is made and handled as an air-stable crystalline solid. o-Anisylcyclohexylmethylphos-phine tetraphenylborate melts sharply at 131°-132°C, [a] 20 + 8.3 (c = 1 in acetone). 

D. Charge Resonance Band in the Near-Infrared Region and Ultrafast Dynamics for Styrylpyridinium Tetraphenylborate Salts... 

Reduction of (4-CH3—C6H4)3PAuN03 by NaBR, in ethanol (molar ratio 4 1) yields a red solution from which a tetraphenylborate salt of the cation [(4-CH3—CgHihPAulg 2 can be precipitated in the form of yellow crystals as a small by-product. [The main product appears in the form of red crystals, originally not further specified (10,12).] The X-ray diffraction analysis gave the cation structure shown in Fig. 4. 

Sekiguchi and coworkers99 100 reported the preparation and the crystal structure of a free cyclotrigermenium cation (9) as a tetraphenylborate salt. The stability of this cation stems from its aromatic lit-electron system, and from the steric bulk of tri-fert-butylsilyl groups. They later expanded this work to similar cyclotrigermenium cations with various substituents and counterions101-103. 

Terminal perfluoroolefins have two fluorine atoms at the double bond. The carbon atoms of the latter bear a significant positive charge, and the nucleophilic agents easily replace the fluorine atoms at the multiple bond. The reactions of binucleophilic reagents with terminal perfluoroolefins form heterocyclic systems. The first step of the reaction involves a nucleophilic attack at the carbon atom of the double bond, generating a carbanion. The latter is stabilized by elimination of the fluoride ion and formation of a new double bond. Subsequent cyclization by the intramolecular attack of the nucleophilic center at the double bond leads to the formation of a heterocyclic system. For example, when a reaction mixture of hexafluoropropylene and sodium dialkylaminodithiocarbamate in dimethylacetamide is heated with aqueous sodium tetraphenylborate, one obtains the tetraphenylborate salt of 2-dialkylamino-4-trifluoromethyl-4,5-difluoro-l,3-dithiolan-2-yl (78JFC(12)193). This compound is formed by intramolecular cyclization of the S-nucleophilic center. 

The white cyrstalline solid is very air sensitive and should be stored in sealed glass tubes. It is soluble in most solvents and is protonated by alcohols, giving [HRu[P(OCH3)3] s]+, which can be isolated as the tetraphenylborate salt. 

The X-ray crystal structure of diphenyl iV-sulfoniosulfimidium 31, crystallized as tetraphenylborate salt, exhibited an S-N-S angle of 108.55° and S-N distances of 1.6433 A and N-S (crown) 1.6559 A <2004NJC959>. Interestingly, the latter distance is almost identical to the S-N distance in the unsubstituted cation 32 <2002CJC1410>. 

Interestingly, while no rearranged / -allylplatinum complex could be detected in solution for either the borate or phosphate salts, the crystals of the tetraphenylborate salt have the -allyI structure whereas the crystals of the hexafluorophosphate salt have the rf-allyl structure . This reflects differences in stabilization of the complex structure due to crystal packing, and thus strongly suggests that the rearrangement is a low energy... 

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 3. The absorption of cyanine dye (Cy) radicals monitored at 430 nm following excitation of a benzene solution with an 18 ps laser pulse. The time dependence of the absorption changes of cyanine radical for the benzyltriphenylborate case is faster than its decay. For the vinyltriphe-nylborate, back electron transfer and the reaction that follows electron transfer have competitive rates. For the tetraphenylborate salt, the back electron transfer process dominates after electron transfer, therefore the boron-carbon bond cleavage does not occur and almost no cyanine dye radical formation is observed (data adapted from [25]).

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