2,4,6-tris phenyl substituent

New aspects in the chemistry of multiple bonds to heteroatoms, considered in particular for 2-silanaphthalene and silabenzene stabilized with 2,4,6-tris[bis(trimethylsilyl)methyl]phenyl substituent at the Si atom 99PAC405. 

Another type of sterically demanding benzamidinate ligands contains the 2,4,6-tris(trifluoromethyl)phenyl substituent at the central carbon atom of the... 

Nickel and palladium react with a number of olefins other than ethylene, to afford a wide range of binary complexes. With styrene (11), Ni atoms react at 77 K to form tris(styrene)Ni(0), a red-brown solid that decomposes at -20 °C. The ability of nickel atoms to coordinate three olefins with a bulky phenyl substituent illustrates that the steric and electronic effects (54,141) responsible for the stability of a tris (planar) coordination are not sufficiently great to preclude formation of a tris complex rather than a bis (olefin) species as the highest-stoichiometry complex. In contrast to the nickel-atom reaction, chromium atoms react (11) with styrene, to form both polystyrene and an intractable material in which chromium is bonded to polystyrene. It would be interesting to ascertain whether such a polymeric material might have any catal3dic activity, in view of the current interest in polymer-sup-ported catalysts (51). 

In some recently discovered tris(pyrazolyl)hydroborato ligands, the 3-phenyl substituent is tethered to the 4-position of the pyrazolyl ring, e.g., tris(2//-benz[G]inda-zol-2-yl)hydroborato. See... 

Acyclonucleosides having a phenyl substituent on the C-T position as in 883 was prepared by condensation of the dioxolane 882 with bis(tri-methylsilyl)thymine in presence of SnCU (90GEP3906357). 

Substituents in the phenyl groups of l. l-dimethoxy-2.4.6-tri-phenyl-phos-phorin have a small effect on the absorption spectra (Table 27). 

The absorption maxima of mixed l-carbo-l-hetero-2.4.6-tri-phenyl-A -phosphorins having R = alkyl or aryl and R = 0-alkyl, 0-aryl, or S-alkyl are given in Table 23 (p. 98). The electronic and steric effects of the substituents are similar to those previously discussed. 

Not only oxidation but also thermolysis of X -phosphorins can lead to cleavage of both 1.1-substituents. According to Markl l.l-dibenzyl-2.4.6-triphenyl-X -phosphorin splits off 1.2-diphenylethane at temperatures higher than 220 °C to form 2.4.6-triphenyl-X -phosphorins22 (seep. 24). Other l.l-carbo-2.4.6-tri-phenyl-X -phosphorins also split off C groups at high temperatures to form 2.4.6-triphenyl-X -phosphorin. The mechanism of cleavage may involve radicals. 

The hydroxide anion catalyzed rate constants for the scries of alkyl tris-(2-methoxyethoxy)silanes obtained by Fohl were used to define a modified Taft equation, log(/cHO//cHO ) = 2.48cr +1.67 Es [42], A good correlation was obtained, except for vinyl and phenyl substituents. The anomalous behavior observed for phenyl and vinyl tris-(2-methoxyethoxy)silanes may have resulted because the steric parameter or the polar parameter may be influenced by the carbon-carbon double bond. The steric parameter for a,yS-unsaturated substituents may include an appreciable resonance effect. The polar parameter values may be influenced by the ability of silicon to back-bond through d orbitals with the a,/J-unsaturated system [37,49]. 

The lithium benzamidinates 8 can be obtained analytically pure by recrystallization from hexane. Unsolvated 8 (R = CF3) is especially remarkable in that it sublimes readily at room temperature and dissolves freely in nonpolar solvents such as toluene or even hexane. Although the molecular structures of 8 (R = CF3) has not been determined by X-ray diffraction, it is highly likely that the 2,4,6-tris(trifluoromethyl)phenyl substituent is responsible for the remarkable properties of this particular lithium benzamidinate. It has been demonstrated that the stabilizing influence of the 2,4,6-tris(trifluoromethyl)phenyl substituent can be traced back to a combination of steric and electronic effects [42]. In addition, this ligand allows the characterization of its derivatives by 19F NMR spectroscopy. 

The close agreement of these numbers is no accident. Styrene was the model compound used to generate the A8 values for a phenyl substituent Now, let us try a more challenging example. ... 

Many 4-hydroxybenzyl substituted 9,10-dihydrophenanthrenes have been isolated from Pleione bulbocodioides [109], Gymnadenia conopsea [105], Bletilla formosana [180] and Arundina graminifolia [181], respectively. Compound 408 from Bletilla formosana is tri-(4-hydroxy- benzyl)-substituted. Some of the sinensol series (409 16) also possess 4-hydroxybenzyl substituents, and others have been prenylated. Sinensol H (416) possesses an unusual phenyl substituent [182,183]. 

A series of ferrocene-based mono and bifunctional tris(pyrazolyl)-borates bearing either methyl or phenyl substituents at the 3-position has been prepared via a fnms-amination reaction. The lithium salts have been converted in the analogous T1 species and [Tl(Fc(Tpph))] has been also structurally characterized. These compounds feature monomeric units with tridentate Fc(Tpph) in striking contrast to the sterically less congested [Tl(Fc(Tp))] that forms polymeric rods in the solid state. In the same paper the authors reported the structure of Tl(Tp) for purpose of comparison.192... 

The vast majority of our work in this area has involved 3,1,2-MC2B9 metallacarboranes in which both cage carbon atoms carry phenyl substituents. We wanted to use the steric bulk of these phenyl substituents to produce crowded metallacarboranes that might accordingly have unusual or interesting properties, but it was first necessary to try to get some feel for the electronic consequences of C-phenyl substitution on the cage. 

The 1,2,3-trihalobenzenes such as 14 (Scheme 1) may carry additional substituents on the ring, thus generating m-terphenyls with additional substituents on the central ring. Two examples are shown. Treatment of 2,4,6-tri-bromoiodobenzene 38 with three equivalents of 21 followed by aqueous workup gave OT-terphenyl 39 [17] with a C5. bromine substituent in 40% yield [Eq. (6)]. Similarly, the m-terphenyl with a C4. phenyl substituent 41 was obtained from 3,5-dibromo-4-iodobiphenyl 40 and 21 in 45% yield [Eq. (7)] [17]. m-Terphenyl-like structures with a 9,10-phenanthroline unit as the central ring... 

Fig. 3.13 The rotating cone. The molecule is a subporphyrin and consists of a central boron in a tri-pyrrole macrocycle. The subporphyrin itself has the shape of a trigonal dome and exhibits C3 symmetry. Three phenyl substituents at the meso-positions are arranged like a propeller and reduce the symmetry to C3. A further symmetry lowering to Ci is caused by an apical hydroxyl substituent at the boron position, with its hydrogen pointing in the direction of the upper phenyl group...

The ring cleavage of mono-, di-, and tri-phenylcyclopropanes by mercuric acetate becomes more difficult as the number of phenyl substituents is increased, with substitution in the aryl ring occurring almost exclusively for (197 = Ph ... 

Edelmann, F. T., "The 2,4,6-Tris(Trifluoromethyl)Phenyl Substituent An Ideal," Comments Inorg, Chem. 1992,12,259. 

Organic and Main-Group Chemistry of the 2,4,6-Tris(trifluoromethyl)phenyl Substituent... 

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