Tetra borates

The Tetra-borate, Co0.4B203.12H20, is obtained 6 by slow evaporation of a solution of cobalt carbonate in boric acid. The precipitate first formed gradually becomes crystalline, rose in colour, but becoming blue on calcination. The decahydrated salt, CoO. 4B203.10H2O, has also been prepared.6... 

Classic A/-heterocychc ligands, eg, bipyridyl (bipy), terpyridyl, imidazole, pyrazine, phenanthroline, piperazine (including alkyl- and aryl-substituted derivatives), and polypyrazol-l-yl-borates (bis, tris, and tetra), have all been found to coordinate Th(IV) chlorides, perchlorates, and nitrates. The tripodal hydrotris(pyrazolyl)borates, HBPz, have been used to stabilize organometaHic complexes (31). Bis-porphyrin Th(IV) "sandwich" complexes have been... 

The use of an electron-accepting counter ion leads to a photochromic system that is highly reversible under an inert atmosphere. An anion that has been used successfully is tetra-bis[3,5-di(trifluoromethyl)phenyl]borate anion [79250-20-9], C22H22BF 24 ( )-... 

The phase relations, stoichiometry and structural chemistry of the metal borates have been extensively studied because of their geochemical implications and technological importance. Borates are known in which the structural unit is mononuclear (1 B atom), bi-, tri-, tetra- or penta-nuclear, or in which there are polydimensional networks including glasses. The main structural principles underlying the bonding in crystalline metal borates are as follows " ... 

Experience in PTC with cationic catalysts showed that, in general, the most suitable compounds have symmetrical structures, are lipophilic, and have the active cationic charge centrally located or sterically shielded by substituents. For anionic catalysis sodium tetraphenylborate fulfills these conditions, but it is not stable under acidic conditions. However, certain derivatives of this compound, namely sodium tetra-kis[3,5-bis(trifluoromethyl)phenyl]borate (TFPB, 12.162) and sodium tetrakis[3,5-bis-(l,l,l,3,3,3-hexafluoro-2-methoxy-2-propyl)phenyl]borate (HFPB) are sufficiently stable to be used as PTC catalysts for azo coupling reactions (Iwamoto et al., 1983b 1984 Nishida et al., 1984). These fluorinated tetraphenylborates were found to catalyze strongly azo coupling reactions, some of which were carried out with the corresponding diazotization in situ. 

The radius ratio for B+3 is only a little less than the lower limit for tetra-hedra. The usual coordination number for boron with oxygen is 3 (in the borate ion, [B03]-3). It is four, however, in the 12-tungstoborate ion,16 in which a stabilizing influence is exerted by the tungsten octahedra. 

BARF tetra[3,5-bis(trifluoromethyl)phenyl]borate BINAP 2,2 -bis(diphenylphosphanyl)-1,1 -binaphthyl BOC t-butoxycarbonyl... 

Chironomus parvae salivary eland cells Na liquid membrane micropipet [ion-exchanger based on tetra(-p-chloro-phenyl)borate] Na 16 mM 149 ... 

The organic solvent should feature a low solubility in water and a high dielectric constant. Numerous studies have been reported for liquid-liquid junctions involving DCE [43,62,70,71,73], nitrobenzene [67,68,74,75], and nitrophenyloctylether (NPOE) [56]. Various hydrophobic electrolytes have been employed in these solvents. Tetraphenylarsonium (TPAs+) [[71,75,76], bis-triphenylphosphoranylidene (BTPPA+) [43,50], and hydrophobic tetra-arylammonium [77,78] are among the cations used in the organic phase. The choice for anions has been mostly restricted to borate derivatives, tetraphenylborate (TPB ) [70,79,80], tetrakis(4-chlorophenyl)borate (TPBCH) [43,81,82], and tetrakis(penta-fluoro)phenylborate (TPFB ) [49,83], as well as dicarbollyl-cobaltate [75]. 

BArF Tetra(perfluorophenyl)borate or tetra(3,5-trifluoromethylphenyl)bortate... 

Among cations, potassium, acetylcholine, some cationic surfactants (where the ion-exchanger ion is the / -chlorotetraphenylborate or tetra-phenylborate), calcium (long-chain alkyl esters of phosphoric acid as ion-exchanger ions), among anions, nitrate, perchlorate and tetrafluoro-borate (long-chain tetraalkylammonium cations in the membrane), etc., are determined with this type of ion-selective electrodes. 

Table 3.4 Features observed by Desilvestro and Pons (1989) during the reduction of C()2 at Pt in 0.1 M tetrabutylammonium tetra fluoro-borate (TBAF)/CH3CN. using in situ FTIR spectroscopy...

The anion plays a crucial role. BArF and other bulky fluorinated tetra-arylbo-rates or tetraalkoxyaluminates are the most suitable anions. Hexafluorophos-phate-containing catalysts display high reactivity in the initial phase of the reaction, but suffer deactivation before the reaction reaches completion. Tetrafluoro-borate, triflate or other more strongly coordinating anions inhibit the catalyst. 

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