Sodium tetraphenylborate
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| Sodium tetraphenylborate | |
|---|---|
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| IUPAC name | Sodium tetraphenylborate |
| Other names | Tetraphenylboron sodium |
| Identifiers | |
| CAS number | [143-66-8] |
| Properties | |
| Molecular formula | (C6H5)4BNa |
| Molar mass | 324.24 g/mol |
| Appearance | white solid |
| Melting point |
>300 °C |
| Solubility in water | 47 g/100 g water |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Sodium tetraphenylborate is the chemical compound with the formula NaB(C6H5)4. It is a salt, wherein the anion consists of four phenyl rings bonded to boron. This crystalline solid is used to prepare other tetraphenylborate salts, which are often highly soluble soluble in organic solvents. The compound is frequently used ininorganic and organometallic chemistry as a precipitating agent.
Contents |
[edit] Sythesis
Sodium tetraphenylborate is synthesized by the reaction between sodium tetrafluroborate and phenylmagnesium bromide.[1]
- NaBF4 + 4 PhMgBr → 2 MgBr2 + 2 MgF22 + NaBPh4
Unlike smaller counteranions, such as nitrate and the halides, tetraphenylborate confers lipophilicity to its salts. Many analogues tetraarylborates have been synthesized, containing both electron rich and electron deficient aryl groups.
[edit] Use in chemical synthesis
[edit] Prepartion of N-acylammonium salts
Addition of sodium tetraphenylborate to a solution of a tertiary amine and an acid chloride in acetonitrile gives the acylonium salt by precipitating NaCl from the reaction mixture. This method has a broad scope:[2]
Sodium tetraphenylborate is also employed as a phenyl donor in palladium-catalyzed cross-coupling reactions involving vinyl and aryl triflates to give arylalkenes and biaryl compoundsin good yields and under mild conditions, respectively.[3]
- RC(O)Cl + R'3N + NaB(C6H5)4 → [RC(O)NR'3][B(C6H5)4] + NaCl
[edit] Coordination chemistry
Tetraphenylborates are often studied in organometallic chemistry because of their favorable solubility in nonpolar solvents and their crystallinity. For example, pentakis(trimethylphosphite) complexes of d8 metals (Ni, Pd, and Pt) have been prepared as their tetraphenylborate salts.[4] Similarly, sodium tetraphenylborate has been used to isolate metal complexes containing dinitrogen.[5] In the reaction below, sodium tetraphenylborate allows N2 to displace the chloride ligand, which is removed from solution as a precipitate of sodium chloride.
- FeHCl(diphosphine)2 + NaB(C6H5)4 + N2 → [FeH(N2)(diphosphine)2][B(C6H5)4] + NaCl
[edit] References
- ^ N. Yakelis and R. G. Bergman (2005). "Safe Preparation and Purification of Sodium Tetrakis[(3,5-trifluoromethyl)phenyl]borate (NaBArF24): Reliable and Sensitive Analysis of Water in Solutions of Fluorinated Tetraarylborates.". Organometallics: 3579. doi:.
- ^ J. King and G. Bryant (1992). "Preparation and characterization of crystalline N-acylammonium salts.". J. Org. Chem.: 5136. doi:.
- ^ P. Ciattini, E. Morera, G. Ortar (1992). "Palladium-catalyzed cross-coupling reactions of vinyl and aryl triflates with tetraarylborates.". Tetrahedron Letters: 4815. doi:.
- ^ J. Jesson, M. Cushing, S. D. Ittel (2007). "Pentakis(Trimethyl Phosphite) Complexes of the d8 Transition Metals". Inorganic Syntheses: 76. doi:.
- ^ M. Mays abd E. Prater (2007). "trans - (Dinitrogen) Bis [Ethylenebis(diethylphosphine)] Hydridoiron(II) Tetraphenylborate.". Inorganic Syntheses: 21. doi:.
