Tetrakis borate anion TFPB

Cyclotrigermenes were obtained from the reaction of metal-14 anions with tris(tri-r-butylsilyl)cyclotrigermenium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, the TFPB behaving as the leaving group (equation 156)168. The cyclotrigermene structure was established by X-ray determination. 

To increase the solubility of the aggregates formed, the large lipophilic TFPB anions (TFPB = tetrakis-(3,5-bis-(trifluoromethyl)-phenyl)-borate) were used instead of the triflate anions [66-68]. The zinc salt [Zn(NCMe)6][TFPB]2 50 was obtained by reaction of zinc bromide with Ag(TFBP) in acetonitrile under exclusion of light. Addition of tetrahydrofuran-dg to a mixture of the cavitand 49 and the zinc salt 50 gave the coordination cage 51 after keeping the reaction mixture at 60 °C for 1 h (Fig. 16). 

TFPB tetrakis[3,5-bis(trifluoromethyl)phenyl]borate anion... 

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. 

These rod-shaped ligands share a sterically efficient terminal N-donor and their divalent Co chemistry is well established. They will be discussed here only with selected examples. [Co (NCMe)6](TFPB)2 (TFPB- = tetrakis(3,5-bis(trifhioromethyl)phenyl)borate)) has been synthesized and characterized in the solid state along with a number of other divalent transition metal analogs.357 As a result of the extremely poor coordinating ability of the anion and facile loss of MeCN ligands from the cation, the salt is an excellent source of naked Co2+ ions. Thermolysis up to 100 °C leads to the loss of one MeCN and formation of a r -bound nitrile, whereas above 130 °C decomposition occurs with loss of MeCN and abstraction of fluoride from the anion to form CoF2. 

The present author has developed a novel method called ion-association method. This is also a simple and versatile method for the preparation of ion-based organic dye nanoparticles in pure aqueous solution by the ion association approach [23]. It utilizes the control of hydrophilicity/hydrophobicity of the ionic material itself via ion-pair formation for example, addition of a cationic target dye solution into aqueous solution containing a certain kind of hydrophobic anions forms an electrically neutral ion-pair because of the strong electrostatic attraction, followed by aggregation of ion-pair species originated from van der Waals attractive interactions between them to produce nuclei and the subsequent nanoparticles (Fig. 3). In this case, hydrophobic but water-soluble anions, such as tetraphenyl-borate (TPB) or its derivatives (tetrakis(4-fluorophenyl)borate (TFPB), tetrakis [3,5-... 

In 1998 the groups of Jprgensen and Helmchen reported the preparation of the chiral silyl cationic salt 2 (Scheme 3) [30]. This was the first time that a chiral silyl cation was used as a catalyst in an enantioselective reaction, hi order to ensure that the silyl salt had a high reactivity, the almost chemically inert and non-coordinating anions tetrakis[pentafluorophenyl]borate [TPFPB] and tetrakis[3,5-bis (trifluor-omethyl)phenyl]borate [TFPB] were chosen as counter anions. 

In a solid salt of viologen MV2+(TFPB")2 where the anion is not the usual chloride but tetrakis[3,5-bis(trifluoromethyl)phenyl]borate (TFPB-), an IPCT absorption is found. When excited in this band in vacuo or under argon, MV + is observed to accumulate and to reversibly disappear when heated or dissolved [208, 209]. This system has also been observed in degassed organic solutions [210] showing that the extraordinarily bulky and stable TFPB- anion works as a reversible electron donor. The MV2+-TFPB- ion pair is also the only example for which ion pair luminescence (optical back electron transfer) is observed at room temperature [211]. 

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