Fluoro carbon complexes

Only complexes of the first three olefins could be isolated as solids whereas the latter three, possibly due to steric restrictions could not be isolated. The tetracyanoethylene complexes were more stable than the hydrocarbon and fluoro-carbon complexes of Ir(I). 

Fluoromethylbenzoic acids, metallation, 9, 26-27 Fluoro(phenyl) complexes, with platinum(II), 8, 482 Fluorosilanes, elimination in fluorinated alkene activation, 1, 732 in fluorinated aromatic activation, 1, 731 and hydrodefluorination, 1, 748 Fluorosilicate anions, hypercoordinated anions, 3, 484 Fluorotoluenes, metallation, 9, 21 Fluorous alkylstannanes, preparation, 3, 820 Fluorous biphasic system, as green solvent, 12, 844 Fluorous ligands, with supercritical carbon dioxide, 1, 82 Fluorous media... 

Reaction of mismatched 3-fluoro R-carbonate 83 with catalytic amounts of 70 (derived from S,S-ligand 64) proceeded with sodium malonate in acetonitrile at 60 °C and the S-adduct 84 and the R-adduct 85 were obtained in a ratio of 88.7 11.3. Complex 71 (20-30 mol%) was added to the reaction mixture of83, 70, and sodium... 

Following earlier studies of the oxidation of formic and oxalic acids by pyridinium fluoro-, chloro-, and bromo-chromates, Banerji and co-workers have smdied the kinetics of oxidation of these acids by 2, 2Tbipyridinium chlorochromate (BPCC) to C02. The formation constant of the initially formed BPCC-formic acid complex shows little dependence on the solvent, whilst a more variable rate constant for its decomposition to products correlates well with the cation-solvating power. This indicates the formation of an electron-deficient carbon centre in the transition state, possibly due to hydride transfer in an anhydride intermediate HCOO—Cr(=0)(0H)(Cl)—O—bpyH. A cyclic intermediate complex, in which oxalic acid acts as a bidentate ligand, is proposed to account for the unfavourable entropy term observed in the oxidation of this acid. 

A DFT study of the geometrical, electronic, and energetic parameters of fluoro derivatives of diphenylborates 9 and 10 and isoelectronic structures where the central atom has been substituted by carbon and nitrogen has also been carried out <2005TA755>. The relative energy of the homochiral versus heterochiral complex has been linearly correlated with the central atom and fluorine substitution on the different positions of the aromatic ring. 

Our group has devoted two articles for the study of systems where the chiral subunits are bonded to a boron or to a metallic atom (Scheme 3.28). In both cases, the weakness of the bonds formed can be easily broken. In the first case, a series of bisdiphenylborates and the effect of the fluoro substitution on the relative stability of the homo vs. heterochiral complexes have been studied by means of DFT calculations (B3LYP/6-31G ) [29]. In addition, the corresponding isoelectronic structures, in which the boron has been substituted by a carbon or a positively charged nitrogen, have been considered. In all the cases, the homo and heterochiral complexes present D2 and S4 symmetries, respectively. 

The chemistry involved in nucleophilic aromatic substitution is well reflected in the reactions of a variety of nucleophiles with methyl penta-fluorophenyl ether (Ingemann et al 1982a). For most of the nucleophiles such as alkoxide, thiolate, enolate and (un)substituted allyl anions, the dominant reaction channel is the attack upon the fluoro-substituted carbon atoms, as is the case for OH-. The latter ion reacts approximately 75% by attack upon the fluoro-substituted carbon atoms and the remaining 25% by Sn2 (20%) and ipso (5%) substitution as summarized in (41). In the attack upon the fluorinated carbon atoms, the interesting observation is made that a F- ion is displaced via an anionic o-complex to form a F- ion/molecule complex, which is not observed to dissociate into F- as a free ionic product. 

The high diastereoselectivity observed is ascribed to effective chelate formation between MeaAl and fluoro carbonyl compounds via pentacoordinate organoalumi-num complex H this was verified by a low-temperature and NMR study. The original signal of the carbonyl carbon in fluoro ketone 61 (model substrate) appeared at 6 208.5. When 61 was complexed with MesAl in a 1 1 molar ratio in CD2CI2 at -50 °C, a significant downfield shift ((5 225.0) was observed for the carbonyl carbon by... 

Addition reactions of the Si-Si bonds across carbon-carbon triple bonds have been most extensively studied since the 1970s by means of palladium catalysts. In the early reports, palladium complexes bearing tertiary phosphine ligands, mostly PPh3, were exclusively employed as effective catalysts, enabling the alkyne bis-silylation with activated disilanes, i.e., disilanes with electronegative elements on the silicon atoms such as hydro [36], fluoro [37], chloro [38], and alkoxy-disilanes [39,40] and those with cyclic structure (Scheme 4) [41-44]. The bis-silylation reactions could be successfully applied to terminal alkynes and acetylenedicarboxylates to give (Z)-l,2-bis(silyl)alkenes, which are otherwise difficult to synthesize. 

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