Tris(pentafluorophenyl)alane

Abstract

[168704-96-9] C18F15Al (MW 528.16) InChI = 1S/3C6F5.Al/c3*7-2-1-3(8)5(10)6(11)4(2)9; InChIKey = POHPFVPVRKJHCR-UHFFFAOYSA-N (strong organo Lewis acid used as catalyst or cocatalyst for abstractions of alkyl, alkoxide, and halide ligands; for additions, CH activation, and formation of adducts with Lewis bases; and for polymerization catalysis) Alternate Name: aluminum, tris (2,3,4,5,6-pentafluorophenyl)-. Physical Data: mp 173–175 °C for Et2O·Al(C6F5)31 or 197 °C for THF·Al(C6F5)3.2 Solubility: soluble in benzene or toluene (with formation of weak Lewis acid–base (solvent) adducts) and polar donor solvents (with formation of strong Lewis acid–base (solvent) adducts); also soluble in polar weakly or none coordinating halogenated solvents, but avoiding CH2Cl2 (with decomposition). Form Supplied in: white solid in the form of (toluene)·Al(C6F5)3 (crystallized)3 or (toluene)0.5·Al(C6F5)3 (vacuum dried).4 Preparative Methods and Purification: Al(C6F5)3 as a toluene or (toluene)0.5 adduct or in its unsolvated form can be readily prepared from the aryl-B/alkyl-Al ligand exchange reaction5 between B(C6F5)3 and AlMe3 or AlEt3 (for the preparation of the unsolvated form in hexanes) in hydrocarbon solvents.6 Any excess amount of AlR3 must be avoided as AlR3 undergoes rapid alkyl/aryl ligand exchange with Al(C6F5)3 to produce various dimeric aluminum species, depending on the ratio of these two reagents.5 Al(C6F5)3 can be purified by crystallization from a 1/3 solvent mixture of toluene and hexanes. Handling, Storage, and Precautions: extra caution should be exercised when handing this compound, especially the unsolvated form (due to its thermal and shock sensitivity)! An explosion was reported in an attempt to sublime the crude etherate prepared from the reaction of AlCl3 and 3 equiv of C6F5MgBr in ether or in an attempt to prepare the unsolvated Al(C6F5)3 by heating a mixture of B(C6F5)3 and AlEt3 to 70 °C.1 Store the solid alane under inert (argon or nitrogen) atmosphere in a glove box and its solutions in a refrigerator inside the glove box.