[Au(η²‐C₂H₄)₃]⁺[Al(OR^F)₄]^– – a Stable Homoleptic (Ethene)gold Complex

Abstract

The simple metathesis reaction of the silver(I) weakly coordinating anion (WCA) salt Ag[Al(ORF)4] {RF = C(CF3)3} with gold(I) chloride and ethene led to the formation of the second isolable tris(ethene)gold(I) complex, the last missing entry in the triad [M(C2H4)3]+[Al(ORF)4]– (M = Cu, Ag, Au). The Au atom is coordinated by three ethene ligands in a distorted trigonal‐planar manner in a so‐called spoke‐wheel arrangement. The formation of the tris(ethene) complex instead of the more expected bis(ethene) complex was analyzed by theoretical investigations and by a Born–Fajans–Haber cycle for [Au(C2H4)3]+[Al(ORF)4]– as well as the only other known example [Au(C2H4)3]+[SbF6]–.

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

“…[336] An h 2bonding motif is also found for the closely related arsenic analogues [Ag(h 2 -As 4 ) 2 ] + and [Au(PPh 3 )(h 2 -As 4 )] + when supported by the [Al(OR F ) 4 ] À anion ( Figure 10). [335,342,343] Silver(I) acetylene complexes have also been characterized, where the number of acetylene ligands coordinated to the silver cation is influenced by the coordinative strength of the WCA.W hen[ Al(OR F ) 4 ] À is employed, the silver coordinates either three or four acetylene ligands to form [Ag(C 2 H 2 ) n ] + (n = 3o r4 )w ith separated cations and anions in the solid-state structure.I nc ontrast, the use of the more coordinating [Al(OC(Me)(CF 3 ) 2 ] À ion results in the formation of [Ag(C 2 H 2 )] + and coordination of the WCA to the silver in the solid state. [338,339] Extension of this reactivity has led to the characterization of the related dicationic selenium complexes [Ag 2 Se 12 ] 2+ and [Cu 2 Se 19 ] 2+ as the [Al(OR F ) 4 ] À salts including weakly bound Se homocycles that are unknown in the free form.…”

“…[458] The D r G8 8 values in the gas-phase and the solid-state entries with the excellent [Al(OR F ) 4 ] À WCA are very similar and only differ by am aximum of 15 kJ mol À1 .T his phenomenon represents the energetic domain of the pseudo-gasphase conditions. [344] Related energetic analyses have been worked out for M + + n C 2 H 4 (n = 1-3) (M = Au,A g, Cu) [335,341,343] and M + + n CO (M = Cu, Ag, Au ; n = 1-4). However, whilst the formation of [Ag(C 2 H 2 ) 4 ] + supported by the small [BF 4 ] À ion is endergonic by an unassailable + 35 kJ mol À1 ,for the much larger [Al(OR F ) 4 ] À anion it is only endergonic by + 3kJmol À1 .T his small value can be overcome experimentally through temperature control:[ Ag(C 2 H 2 ) 4 ] + [Al(OR F ) 4 ] À forms in ac losed container under aC 2 H 2 atmosphere.Inthe closed system it loses acetylene above À20 8 8C.…”

“…[341] This principle can be extended to [M(C 2 H 4 ) 3 ] + (M = Cu, Au). [335,342,343] Silver(I) acetylene complexes have also been characterized, where the number of acetylene ligands coordinated to the silver cation is influenced by the coordinative strength of the WCA.W hen[ Al(OR F ) 4 ] À is employed, the silver coordinates either three or four acetylene ligands to form [Ag(C 2 H 2 ) n ] + (n = 3o r4 )w ith separated cations and anions in the solid-state structure.I nc ontrast, the use of the more coordinating [Al(OC(Me)(CF 3 ) 2 ] À ion results in the formation of [Ag(C 2 H 2 )] + and coordination of the WCA to the silver in the solid state. [344]…”

“…Ford etermination of its X-ray crystal structure,i th ad to be mounted at À50 8 8C. [344] Related energetic analyses have been worked out for M + + n C 2 H 4 (n = 1-3) (M = Au,A g, Cu) [335,341,343] and M + + n CO (M = Cu, Ag, Au ; n = 1-4). [459] Structural Domain:T he solid-state ion packing of true salts containing av ery large WCA lead to the lattice in the crystal being essentially determined by the anion.…”

From unsuccessful H2-activation with FLPs containing B(Ohfip)3 to a systematic evaluation of the Lewis acidity of 33 Lewis acids based on fluoride, chloride, hydride and methyl ion affinities

“…These values underline its current role in chemistry to stabilize highly reactive cations. 14,33,38,39,42,43,[48][49][50]100,101 In addition, Table 5 102 Typically, the fluorination of ligands increases the stability values of borate based anions. 18 Apart from that, the stability values of all the WCAs including M-C bonds are quite similar.…”