Synthesis of Pentafluorophenyl Silver by Means of Lewis Acid Catalysis: Structure of Silver Solvent Complexes

Abstract

The synthesis and structure of lithium and silver tetrakis(pentafluorophenyl)borate salts have been studied in different solvents ranging from polar (CH 2 Cl 2, diethyl ether) to nonpolar (toluene, pentane). While Li[B(C 6 F 5 ) 4 ] is stable in all studied solvents and crystallizes with four ether molecules from ether and with two toluene molecules from toluene, the silver salt is only stable when the Ag + ion is strongly coordinated such as in [Ag(toluene) 3 ][B(C 6 F 5 ) 4 ] or [Ag(Et 2 O) 3 ][B(C 6 F 5 ) 4 ]. In weakly coordinating solvents such as CH 2 Cl 2 Ag[B(C 6 F 5 ) 4 ] decomposes, yielding AgC 6 F 5 and B(C 6 F 5 ) 3 . The overall process of the AgC 6 F 5 synthesis starting from B(C 6 F 5 ) 3 and LiC 6 F 5 can formally be regarded as a B(C 6 F 5 ) 3 -catalyzed reaction. The salt [Ag(toluene) 3 ][B(C 6 F 5 ) 4 ] presents an easily accessible, ether-free, stable silver salt of the [B(C 6 F 5 ) 4 ] − anion. All compounds have been fully characterized.