Gold pentafluorophenyl

Figure 2.3 Selected examples of (pentafluorophenyl)gold(lll) complexes with monodentate N-ligands.

The first thing to point out is that the use of a pentafluorophenyl CgFs group with late transition metal confers on the complexes great stability, both thermodynamic and kinetic. This general fact, that is also true in gold chemistry, can be explained by different factors ... 

Unlike alkyl-gold bonds the Au—C bonds in pentafluorophenyl compounds are more resistant to cleavage by protic acids, giving more chemical integrity to the complexes. 

The pentafluorophenyl group imparts greater crystallinity to the complexes and as a result many complexes have been studied by X-ray crystallography. Although vith other metal centers C Fs-CaFs or CfiFs-CfiHs n-n stacking interactions are observed [21, 22], there are not many examples in gold chemistry and they have been sho vn very recently [23]. 

The reaction of the gold(I) pentafluorophenyl isocyanide complexes with primary and secondary amines as well as alcohols leads to the corresponding gold(I) [62, 65] carbenes (Table 3.2). The addition of amines leads to the corresponding carbenes... 

The cyclic carbene complex shown in equation 3.4 was studied by X-ray diffraction [66], it shows a linear complex (angle C—Au—C 178.6(4)°) and the gold aryl bond distance is 1.993(10) A which is in accordance with such bonds in other known pentafluorophenyl complexes. The gold carbene carbon distance is 1.961(9) A, the dihedral angle between the planes formed by the two organic ligands is 5.35° and the shortest intermolecular Au—Au distance is 3.95 A. 

The gold(I) complex [Au(C6F5)(tht)] has been used as starting material to synthesize numerous anionic Au(I) pentafluorophenyl derivatives as shown in Table 3.3. 

Polynuclear Au(I) pentafluorophenyl complexes can also be obtained by reaction of [AulCfiFsjItht)] with polydentate ligands or with gold complexes that still have different coordination sites or can be created before the subsequent reaction. The ligands or complexes that react with [Au(C6F5)(tht)] and the complexes obtained are listed in Table 3.6. 

When [AuTl(C6F5)2]n reacts with DMSO the complex [Tl2 Au(C6F5)2 2 lt-DMSO 3]n [126] is obtained. The crystal structure of this complex shows unsupported Au - Tl interactions that range from 3.2225(6) to 3.5182(8) A but there are no Tl- - - Tl interactions. There are Au- - - Au interactions of3.733 A and the gold centers are almost linearly coordinated to two pentafluorophenyl groups. The complex is strongly luminescent both at room temperature (emits at 440 nm (exc.390 nm)) and at 77 K (emits at 460 nm (exc. 360 nm)). 

Neutral ylide, isocyanide and carbene pentafluorophenyl gold] 111) complexes with the general formulae trans-[Au]C6F5)X2]CH2PR3)[ ]PR3 = PPh3, PPh2Me, PPhMe2),... 

A different way to prepare pentafluorophenyl gold] 111) complexes is depicted by replacement of the halogen atom from the starting material as MCI or AgCl. Some examples are illustrated by the following equations (Equations 3.13-3.19) ... 

The ligands N-[bis(isopropoxy)thiophosphoryI]thiobenzamide and N-[bis(isopro-poxy)thiophosphoryl]-N -phenylthiourea can be deprotonated with the acetylacetonate gold(III) derivative [Au(C6F5)2(acac)] [26] giving the corresponding pentafluorophenyl complexes with the ligand acting as a chelate one [192]. 

Cation-radical salts with pentafluorophenyl gold(III) anions such as (TTFPh2)2.s[Au(C6F5)2Cl2] and (TTFPh2)[Au(C6F5)2l2], where TTFPh2 is the donor molecule 4,4 -diphenyltetrathiafulvalene, can be performed by electrocrystallization techniques [83]. 

Coordination of pentafluorophenyl gold(III) to the two free N-donor atoms in 1,1 -bis(2-pyridylthio)ferrocene leads to the dinuclear complex [ Au(C6F5)3 2 Fc(Spy)2 ] structurally characterized [149]. 

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