Gold(II) Trihalide Complexes from Organogold(III) Precursors

Abstract

The mononuclear gold(II) halide complexes [AuCl ] and [AuBr ] are formed in the gas phase by collision-induced homolytic splitting of the only Au-C bond in the monoalkylgold(III) precursors [CF AuX ] . The geometries of the whole series of [AuX ] complexes (X=F, Cl, Br, I) have been calculated by DFT methods. It has also been found that the neutral AuX molecules behave as unsaturated species, showing significant affinity for an additional X ligand. Moreover, in the open-shell [AuX ] anions, homolytic splitting of one of the Au-X bonds and formation of the lower-valent [AuX ] anions is favored over non-reducing halide dissociation. They should therefore be prone to disproportionation.

An Organogold(III) Difluoride with a trans Arrangement

“…[16] Thee ntire CF 3 -Au-F axis in this gold(III) compound shows little structural difference with the linear gold(I) complex [CF 3 AuF] À (Figure 3b), regardless of the different oxidation state and coordination number of the metal in each case.A similar Au À Cd istance (203.5 pm) is calculated for the cis isomer of the unsaturated, open-shell [CF 3 AuF 2 ] À complex ( Figure 4);i ti s, however,s ubstantially elongated in the TS (216.5 pm) and even more so in the trans isomer (225.5 pm). [15] This also evidences ahigh degree of covalencyf or the AuÀCF 3 bond. Thus,the spin density on the CF 3 group is negligible in the cis isomer, whereas it amounts > 50 %i nt he trans isomer.I ti sworth noting that the unpaired electron is much less delocalized when the stem ligand is fluorine.Inthis case, the spin density resides mainly on the Au atom (72 %), with just 24 %delocalized onto the stem Fatom.…”

“…It undergoes various collision-induced dissociation processes (Figures S8-S12), which are summarized in Scheme 2. [15] It was also observed to arise by FC dissociation from the inorganic [AuF 4 ] À anion. All other fragmentations involve metal reduction by one (radical dissociation) or two units (reductive elimination or double radical dissociation).…”

“…All other fragmentations involve metal reduction by one (radical dissociation) or two units (reductive elimination or double radical dissociation). [15] Theg eometries of the experimentally detected organogold fluoride complexes [CF 3 AuF x ] À (x = 1, 2, 3) have been optimized by DFT methods.T he saturated species of gold-(III) and gold(I) show the structures depicted in Figure 3. Homolytic splitting of aA u ÀCF 3 bond gives rise to the organogold(II) difluoride [CF 3 AuF 2 ] À ,w hich again suffers AuÀCh omolysis to yield [AuF 2 ] À (Scheme 2b).…”

An Organogold(III) Difluoride with a trans Arrangement

“…This open-shell derivative was recently assigned aTshaped structure. [15] It was also observed to arise by FC dissociation from the inorganic [AuF 4 ] À anion. [11a] With the aid of MS 4 experiments ( Figure S12), we have now detected that the [AuF 3 ] À anion itself undergoes radical dissociation of FC atoms giving rise to [AuF 2 ] À .T his fact is in line with the behavior of the heavier homologues [AuCl 3 ] À and [AuBr 3 ] À , and confirms our previous calculations.…”

The First Organosilver(III) Fluoride, [PPh4][(CF3)3AgF]

“…Instead, formation of CF 3 Ht ogether with trifluoromethylation of the [PPh 4 ] + cation (FigureS15, SI) are in keeping with CF 3 C generation, thus favoring the radical path. [31] Furthermore,p redominant formation of the homoleptic [(CF 3 ) 4 Ag] À derivative ( Figure S15, SI) gives unequivocal proof for intermolecularp rocesses operating in the condensed phase, whicha re necessarily absent in the gas phase.…”