Striking ligand-disproportionative Cl/aryl scrambling in a simple Au(iii) system. Solvent role, driving forces and mechanisms

Abstract

Aryl rearrangements triggered by Cl extraction from starting from trans-[AuIII(Rf)2Cl2]– (Rf = C6F3Cl2-3,5), led fastly to a mixture of [Au(Rf)3(solv)], [Au(Rf)2Cl(solv)], and [Au(Rf)Cl2(solv)] (solv = OEt2, OH2). 19F NMR and...

Synthesis and Structural Characterization of Phosphanide Gold(III)/Gold(I) Complexes and Their Thallium(III) and Gold(III) Precursors

“…The mutually trans Au–C bond lengths, of 2.073(3) and 2.068(3) Å, are longer than the Au–C trans to sulfur, of 2.035(3) Å, according to the higher trans influence of the aryl groups than S-donor ligands, and compare well with the Au–C bond lengths described for the mutually trans aryl groups in [Au(3,5-C 6 Cl 2 F 3 ) 3 (OH 2 )] (2.056(7) Å) or in the anion [Au(3,5-C 6 Cl 2 F 3 ) 4 ] − (2.059(5) Å) [ 23 ] ( Table 2 ). In addition, all the Au–C bond lengths in [Au(3,5-C 6 Cl 2 F 3 ) 3 (tht)] ( 2 ) are almost equal to those found for its pentafluorophenyl analogue (Au–C trans to C 6 F 5 : 2.056(5)-2.068(2) Å and Au–C trans to S: 2.030(5) and 2.032(3) Å) [ 41 ].…”

“…As mentioned above, our interest was focused not only on the synthesis of new diphenylphosphane and phosphanido-bridged compounds, but also on the preparation of unknown starting materials for the subsequent synthesis of such gold(III) species. Considering the difficulties involved in the oxidation of the bis(aryl)aurate(I) anion [Au(3,5-C 6 Cl 2 F 3 ) 2 ] − commented on above, which leads to mixtures of different aryl gold(III) complexes [ 23 ], we decided to employ the neutral gold(I) compound [Au(3,5-C 6 Cl 2 F 3 )(tht)] as starting material. Nevertheless, the first target was the synthesis of the appropriate oxidizing complex to treat [Au(3,5-C 6 Cl 2 F 3 )(tht)] with.…”

“…With these precedents, we focused our interest in the synthesis of phosphanido gold(III) complexes, and with this aim, we thought of the possibility of employing the poorly represented 3,5-dichlorotrifluorophenyl group as a ligand bonded to gold, which could modify the electronic and steric effects in the new complexes and could confer them different stability and properties. However, surprisingly, the synthesis of gold(III) species with this perhalophenyl ligand seems to be not as obvious as expected, and when the same procedures as those employed to prepare trans -[Au(C 6 F 5 ) 2 × 2 ] − [ 21 ], cis -[Au(C 6 F 5 ) 2 X 2 ] − [ 21 ] and [Au(μ-Cl)(C 6 F 5 ) 2 ] 2 [ 22 ] are followed, a quick rearrangement of aryl groups occurs, and a mixture of [Au(3,5-C 6 Cl 2 F 3 ) 3 (solv)], [Au(3,5-C 6 Cl 2 F 3 ) 2 Cl(solv)] and [Au(3,5-C 6 Cl 2 F 3 )Cl 2 (solv)] (solv = OEt 2 , OH 2 ) is obtained [ 23 ].…”

Intimate relationship between C–I reductive elimination, aryl scrambling and isomerization processes in Au(iii) complexes

“…We recently reported that, trying to synthesize (μ-Cl) 2 [AuRf 2 ] 2 , an unexpected Rf/Cl scrambling process was observed (Scheme 1, above). 7 There are just a few reported cases of aryl scrambling phenomena involving Au( iii ) complexes. Those reported by Luzuriaga 8 (Scheme 1, middle) and Nevado 9 groups (Scheme 1, below), have in common that they are only detected when strong oxidants come into play, and are lacking any mechanistic investigation.…”

“…On the contrary, accessible Rf–Rf reductive elimination (RE) barriers were observed for cis -[AuRf 2 Cl(L)] (L = μ-Cl, OEt 2 ) derivatives, while no traces of Rf–Cl (hypothetically resulting from a C–Cl coupling) were detected in any case. 7…”