Fluorinated Weakly Coordinating Anions [M(hfip)₆]^– (M = Nb, Ta): Syntheses, Structural Characterizations and Computations

Abstract

Abstract The synthesis, spectroscopic and structural characterisation of a series of [M(hfip) 6 ] – (M = Nb, Ta; hfip = O–C(H)(CF 3 ) 2 ) salts that are the typical starting materials to introduce these weakly coordinating anions by metathesis reactions into a given system is described. The salts Li[Nb(hfip) 6 ] and Li[Ta(hfip) 6 ] formed in 65 to 77 % yield from freshly sublimed MCl 5 and Li[hfip]. By contrast, several attempts to synthesize Li[Sb(hfip) 6 ] on the similar route (replace NbCl 5 by SbCl 5 ) failed to yield a pure product. Upon metathesis of the Li‐niobate with AgF in CH 2 Cl 2 , the pure Ag[Nb(hfip) 6 ] formed. Mixing Li[Nb(hfip) 6 ] with an equimolar amount of Cl–CPh 3 in CH 2 Cl 2 gave the yellow [CPh 3 ][Nb(hfip) 6 ]. Several of the compounds were characterized by X‐ray analysis. Thus, the crystal structures of the Li + ‐ and Ag + ‐solvates 1, 2‐C 6 H 4 F 2 {LiNb(hfip) 6 } 2 , [Li(H 2 O)][Ta(hfip) 6 ], and [Ag(C 6 H 5 F)][Nb(hfip) 6 ] as well as that of [CPh 3 ][Nb(hfip) 6 ] were solved and are described in this work.