Complexes pentafluorophenyl

Fig. 8. Rephcation. The amino adenosine X and the pentafluorophenyl ester Y form a hydrogen-bonded dimer XY, prior to reaction between the amine and the activated ester groups (shown in the circle). The reaction product is a <7 -amide conformer cis-Z that isomeri2es to the more stable trans- acnide Z. The rephcative process is cataly2ed by the reaction product Z (also referred to as the template). First, a termolecular complex XYZ is formed from X, Y, and Z.

Bis(pentafluorophenyl)cadmium complexes have been used to prepare tri-methyl(pentafluorophenyl)tin [4 (equation 15)... 

Perfluoroalkyl or -aryl halides undergo oxidative addition with metal vapors to form nonsolvated fluonnated organometallic halides and this topic has been die subject of a review [289] Pentafluorophenyl halides react with Rieke nickel, cobalt, and iron to give bispentafluorophenylmetal compounds, which can be isolated in good yields as liquid complexes [290] Rieke nickel can also be used to promote the reaction of pentafluorophenyl halides with acid halides [297] (equation 193)... 

A powerful variation of the iron acetyl enolate aldol reaction utilizes the cnolate of complex 8 which bears a (pentafluorophenyl)diphenylphosphane ligand in place of the more usual triphenylphosphane47. The enolate species 9. prepared by treatment of 8 with lithium diiso-propylamide, reacts at — 78 °C with benzaldehyde to produce the aldol adduct 10 with a d.r. of 98.5 1.5. 

The heavy alkaline earth metals Ca, Sr, and Ba react with 2 equivalents of NJ -bis(2,6-diisopropylphenyl)formamidine in the presence of bis(pentafluorophenyl)-mercury to afford the bis(formamidinato) species as THF adducts in good to moderate yield (Scheme 23). When the same reactions are carried out in a 1 1 molar ratio, N-p-tetrafluorophenyl-N,N -bis(2,6-diisopropylphenyl)formamidine is isolated as the sole product in all cases (Scheme 23). Other substituted N -bis(aryl)formamidinate complexes of the heavy alkaline earth metals were synthesized accordingly. ... 

HPentafluorophenyOadamantane, 59, 130 (Pentafluorophenyl)benzene, 59, 127 Pentafluorophenylcopper, 59, 124 Pentfluorophenylcopper complexes, 59, 127 PENTAFLUOROPHENYLCOPPER TETRAMER, 59,122 2-(Pentafluorophenyl)ethylamine hydrochloride, 57, 82... 

Decomposition of diazo compounds by iron porphyrins is a convenient method for the synthesis of non-heteroatom carbene-iron porphyrins [22]. Reaction of [Fe(F2o-TPP)] [F20-TPP = meso-tetrakis(pentafluorophenyl)porphyrinato dianion] with diazo compounds N2C(Ph)R (R = Ph, C02Et, C02CH2CH=CH2) under an inert atmosphere afforded complexes [Fe(F2o-TPP)C(Ph)R] in 65-70% yields (Scheme 2). Like the halocarbene complex [Fe(TPP)(CCl2)], [Fe(F2o-TPP)CPh2] reacted with Melm to afford six-coordinate species [(MeIm)Fe(F2o-TPP)CPh2] in 65% isolated yield. 

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. 

When the Au(I) pentafluorophenyl complex [Au(C6F5)(tht)] reacts with a phosphine the tht ligand is easily displaced to give the corresponding phosphine complexes. This was the method employed to obtain all the following complexes. 

The reaction with PPh2CCH leads to the formation of [Au(QF5)(PPh2CCH)[ [53] whose P H NMR spectrum shows a singlet at 17.2ppm, in the H NMR spectrum the resonance of the C = CH proton is observed at 3.46 ppm. The IR spectrum shows, besides the pentafluorophenyl absorptions, a band at 3271 cm due to the V(Csch) and another absorption at 2056 cm for the asymmetric C = C stretch. The structure of this complex was studiedby X-ray diffraction, the Au(I) atom is an almost linearly coordinated and the Au—C and Au—P distances are in the range of the values found for similar complexes. The excitation and the emission data in the solid state at 77 K are 331 and 445 nm. 

Neutral Au(I) pentafluorophenyl complexes with heterocyclic thiones can be prepared by displacement of the tht ligand in [Au(QF5)(tht)] with a thione [49] as shown in Equation 3.6. 

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. 

The trinudear complex [Au3(p-triphos)(QF5)3] [97] in dichloromethane shows an absorption around 270 nm and in the solid state at room temperature the complex does not emit, even using an excitation frequency below 300 nm. At lower temperature (77 K) the complex emits with a maximum at 450 nm. Thus luminescence properties can be dramatically influenced by the pentafluorophenyl group which indicates its important contribution to the energy levels involved in the electronic transitions. 

The trinuclear complex [(Au2S2CNR2)] (PPh2)3CH Au(C6F5)] [102] (Figure 3.10) has an IR spectra that confirms the presence of the pentafluorophenyl group bonded to the Au(I) atom. The P H NMR spectrum shows a doublet at 43.6 ppm and a triplet at 41.2 ppm while the F H NMR spectrum shows the typical pattern for the pentafluorophenyl group bonded to the Au(I) atom. 

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