Pentafluorophenyl derivatives

Pentafluorophenyl derivatives have received wide application in biochemistry as highly selective and efficient protective reagents (for a review, see reference 148)... 

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. 

The synthesis of di- or tri-nudear pentafluorophenyl derivatives by the use of polydentate ligands with [AulCgFsjltht)] is quite a general procedure as shown in Table 3.4. Many of these complexes have been characterized by X-ray diffraction and show short Au Au contacts as in [(CgFsjAulSdppmSjAulCfiFs)] [88] of 3.163(1) Aor in the dinuclear complex [57] shown in Figure 3.8 of 3.4671(9) A. 

Pentafluorophenyl derivatives of the type [AgR] where prepared many years ago. A new method consists of the reaction of Bu4N[AuR2] with AgC104 (Equation (4)) 3, 301... 

Magnetic nonequivalence is not uncommon, often deriving from the constraints of a ring, as in pentafluorophenyl derivatives or other symmetrically fluorine substituted ring systems such as those shown in Scheme 2.10. The fluorine and proton NMR spectra of 1,2-difluoroben-zene are both representative of the appearance of second order spectra of polyfluoroaromatics. They can be found in Chapter 3, Section 3.9.3. 

The pentafluorophenyl derivatives are particularly revealing, since the polarization transferred to the individual 19F positions can be compared and correlated with different concepts of their interactions with the primarily spin polarized protons [48]. The enhancement factors achieved in the hydrogenation products of monosubstituted compounds at low field under ALTADENA conditions are given in Figure 12.32. 

The n.m.r. spectra of the alkyl compounds were studied in detail, and a crystal structure has been completed on the pentafluorophenyl-derivative.19... 

Miller (90), King (209, 210), and Bruce (211) first observed the formation of neutral metal fluoride species and metal fluoride-containing ions in the mass spectra of pentafluorophenyl derivatives of phosphorus, germanium, silicon, and phosphido-bridged iron carbonyls (90) and aliphatic and aromatic fluorocarbon derivatives of iron, cobalt (209-211),... 

Cavell and Dobbie (214-216) have suggested that halogen transfer rearrangements in trifluoromethylphosphines arise from interactions of nonbonding fluorine p orbitals with vacant d orbitals on phosphorus. Such an explanation is consistent with observations for the Groups IV and V pentafluorophenyl derivatives, exclusive of carbon and nitrogen, and similarly fits the behavior of boron with its vacant p orbital. 

Similarly to the results observed in the previous case, the structural differences affected the optical properties of the complexes. While in the former a single emission was observed in the solid state, both at room temperature (440, exc. 390 nm) and at 77 (460, exc. 360 nm) the latter showed one band (510, exc. 450 nm) and one shoulder (560 nm) at room temperature, and two independent emissions (510, exc. 370 nm 550, exc. 480 nm) at 77 K. This pentachlorophenyl derivative was also luminescent in solution, displaying a band at 530 nm (exc. 345 nm), which was not present in the precursor complexes or in the pentafluorophenyl derivative. Therefore, in this case, as in the previous one, it is proposed that the TI H interaction in the solid state remained in solution and was responsible for the luminescence behavior observed in this state. 

The relative rates of acylation and of deoxygenation have been determined with these various reagents [44]. As expected, the pentafluoro reagent reacts the fastest with an alcohol under standard conditions, followed by the 4-fluoro reagent, and the phenyl derivative is the slowest. However, for the deoxygenation reaction the fastest group is the methyl xanthate. The slowest is the pentafluorophenyl derivative. This is not important because all of the thiocarbonyl derivatives mentioned give very fast radical reactions 144],... 

Magnetic nonequivalence is not uncommon, often deriving from the constraints of a ring, as in pentafluorophenyl derivatives or other... 

Also, the pentafluorophenyl derivatives Q[Au(C6F5)(SH)] (Q = PPN, NBu4, NEt4)41 and PPN[Au(C6F5)(C=CH)]42 (whose crystal structure has been described previously) can be obtained following the synthetic procedure represented in Scheme 2. 

Cationic heterodinuclear complexes derived from ferrocenyl are not as common as their neutral analogs, and only the pentafluorophenyl derivative [(C6F5)Au (PPh2CH2PPh2CH2Fc)]TfO has recently been prepared by treatment of the phosphonium-phosphine salt [FcCH2PPh2CH2PPh2]TfO with equimolecular amounts of [Au(C[Pg.101]

The pentafluorophenyl derivative (C6F5)2Cd is hydrolyzed by water to give the tetrameric cadmium hydroxide complex [(C6F5)Cd(/u-OH)]4 (equation 13). The molecular structure (10) of [(C6F5)Cd(/u-OH)]4 is based on a cube with the cadmium and oxygen atoms occupying the vertices. The hydroxy derivative is characterized by observation of a v(OH) band at 3640 cm. ... 

Trifluorovinyl and pentafluorophenyl derivatives of tin [11, 15] can be obtained readily via magnesium or lithium derivatives. It is interesting that the stability of (CH3)3SnCgF5 to hydrolysis is very dependent on purity in the presence of fluoride ion, rapid hydrolysis occurs and a process involving initial co-ordination of fluoride ion, and other halide ions, to tin has been suggested [111] (Figure 10.53). 

On treatment with LDA, bis(pentafluorophenyl) derivative 186 gave the ring closed product 188. Apparently, the reaction proceeds through a nucleophilic aromatic substitution in the presumed intermediate 187 (Scheme 19) <2004JA11046>. 

Preparative methods have been devised for two new phosphonothioic dichlorides RP(S)C12, where R = 2-chlorocyclohexyl and 1-cyclohexen-l-yl,594 and for the pentafluorophenyl derivatives C6F5P(S)X2, R(C6F5)P(S)X, and (C6Fs)2P(S)X.595 Compounds with the general formula [R2P(X)]2Y, where X and Y = O or S, have been prepared for detailed n.m.r. 

Modified MAOs (MMAO) that incorporate Bu and other alkyl groups to improve stability and optimize catalytic activity are commercially available. The use of additional modifiers such as boranes, boroxines, and pentafluorophenyl derivatives has been investigated in recent years. MAO has also been supported on silica and other materials for the preparation of heterogeneous alkene polymerization catalysts. These developments are detailed in several reviews. ... 

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