Synthesis, Properties, and Application of Tetrakis(pentafluoroethyl)gallate, [Ga(C₂F₅)₄]⁻

Abstract

Weakly coordinating anions (WCAs) are important for academic reasons as well as for technical applications. Tetrakis(pentafluoroethyl)gallate, [Ga(C2F5)4]−, a new WCA, is accessible by treatment of [GaCl3(dmap)] (dmap=4‐dimethylaminopyridine) with LiC2F5. The anion [Ga(C2F5)4]− proved to be reluctant towards deterioration by aqueous hydrochloric acid or lithium hydroxide. Various salts of [Ga(C2F5)4]− were synthesized with cations such as [PPh4]+, [CPh3]+, [(O2H5)2(OH2)2]2+, and [Li(dec)2]+ (dec=diethyl carbonate). Thermolysis of [(O2H5)2(OH2)2][Ga(C2F5)4]2 gives rise to a dihydrate of tris(pentafluoroethyl)gallane, [Ga(C2F5)3(OH2)2]. All products were characterized by NMR and IR spectroscopy, mass spectrometry, X‐ray diffraction, and elemental analysis. Furthermore, an outlook for the application of [Li(dec)2][Ga(C2F5)4] as a conducting salt in lithium‐ion batteries is presented.

Pentafluoroethylaluminates: A Combined Synthetic, Spectroscopic, and Structural Study

“…[c] [PPh 4 ][Al(C 2 F 5 ) 4 ]; Symmetry: S 4 [37] . [d] [PPh 4 ][Ga(C 2 F 5 ) 4 ]; Symmetry: S 4 [18] . [e] PNP [(C 2 F 5 )AlF 3 ]; the [(C 2 F 5 )AlF 3 ] − anion is disordered with [(C 2 F 5 )AlClF 2 ] − ( d (Al‐Cl)=211.9(4) [exptl] and 217.2 pm [calcd]).…”

“…The successive degradation of the related gallate anion [Ga(C 2 F 5 ) 4 ] − (Figure 1) [18] that exhibits a much higher thermal and chemical stability in its salts than [Al(C 2 F 5 ) 4 ] − was studied by DFT calculations, as well (Figure 4). The data available show that the loss of CF(CF 3 ) via an 1,2‐fluorine shift is favored over TFE elimination via an 1,3‐fluorine shift.…”

“…The tetrakis(trifluoromethyl)gallate anion [Ga(CF 3 ) 4 ] − , [19] the gallane Ga(CF 3 ) 3 , [20] and some of its adducts (CF 3 ) 3 Ga⋅ L ( L= PMe 3 , AsMe 3 ) [20] have been synthesized and characterized by NMR spectroscopy. Recently, Hoge and co‐workers reported on salts of the tetrakis(pentafluoroethyl)gallate anion [Ga(C 2 F 5 ) 4 ] − (Figure 1) and its application in Li‐ion batteries [18] . In addition, first examples of related tris(pentafluoroethyl)gallane derivatives were described [18, 21] .…”

“…Recently, Hoge and co‐workers reported on salts of the tetrakis(pentafluoroethyl)gallate anion [Ga(C 2 F 5 ) 4 ] − (Figure 1) and its application in Li‐ion batteries [18] . In addition, first examples of related tris(pentafluoroethyl)gallane derivatives were described [18, 21] . Tris(trifluoromethyl)indium In(CF 3 ) 3 , [22] some donor‐stabilized adducts (CF 3 ) 3 In⋅ L ( L= PMe 3 , [22] DMF), and few additional perfluoroalkylindium compounds, for example, (CF 3 ) 2 InCl, [19] were reported [19, 23, 24] .…”

Oxygen‐Bridged Ga2(Et)3(OTeF5)3 and the Weakly Coordinating Anions [Ga(Et)(OTeF5)3]− and [Ga(OTeF5)4]−

“…[17,18] To expand our repertoire of WCAs we were interested in the higherh omologue of [Al(OTeF 5 ) 4 ] À .O nly af ew examples of weakly coordinating anionsb ased on gallium have been reported so far ([Ga(CF 3 ) 4 ] À , [19] [Ga(C 6 F 5 ) 4 ] À[20] ,a nd [Ga(C 2 F 5 ) 4 ] À . [21] The useful properties of the pentafluoroorthotellurate group (OTeF 5 group), robustnessa gainst electrophiles and high steric demand [22] was already used to prepared bulky WCAs with the molecular formula [M(OTeF 5 ) 6 ] À (M = As, [23,24] Nb, [25][26][27] Sb, [24,26,28] Ta , [27] and Bi [24] )a nd let us extendt hat concept.…”