Phenyl complexes

Figure 28.3 (a) Silver(III) ethylenedibiguanide complex ion the counter anion can be HSO4, C104 , NOs" or OH . (b) Gold(III) (dimethylamino)phenyl complex ion the counter anion can be Bp4 or C104 . 

Fe—N4 plane displacements of over 0.15 A, consistent with low spin Fe(lll) centers." The Fe—C bond lengths in the iron(lll) complexes are shorter (less than 2 A) than that in the iron(Il) complex (greater than 2 A). The shorter bond length for the phenyl complex Fe(TPP)Ph relative to the methyl complex Fe(TAP)Me is consistent with a stronger aryl Fe—C bond in the former. 

Kwiatek and Seyler were the first to report that many organopenta-cyanides, when treated first with acid and then with alkali, liberate nitriles 110). This reaction occurs with unsubstituted primary and secondary alkyl, benzyl, vinyl, and phenyl complexes, while allyl, 2-oxo-, 2-hydroxy-, and 2-alkoxy complexes simply release the organo-ligand on treatment with acid, and 1-cyanoalkyl and a-pyridyl complexes are stable 105) (see also Table IV). The yield of nitrile is usually far from quantitative and is... 

Further investigations revealed that this hydrogenation is accelerated in pentane solution. These results are shown in brackets in Table 3 [31]. Under optimized reaction conditions high catalyst TOF up to 5,300 were achieved when 10 was used. In the absence of both hydrogen and nitrogen, 10 was converted into the q -arene complexes such as the bis(imino)pyridine iron q -phenyl complex, 10-Phenyl, and the corresponding q -2,6-diisopropylphenyl complex, 10-Aryl, in the 85 15 ratio in... 

The above-described reverse reaction (viz. the Fe-catalyzed dehydrogenation of alcohols to ketones/aldehydes) has been reported by Williams in 2009 (Table 9) [58]. In this reaction, the bicyclic complex 16 shows a sluggish activity, whereas the dehydrogenation of l-(4-methoxyphenyl)ethanol catalyzed by the phenylated complex 17 affords the corresponding ketone in 79% yield when 1 equiv. (relative to 17) of D2O as an additive was used. For this oxidation reaction, l-(4-methoxyphenyl) ethanol is more suitable than 1-phenylethanol and the reaction rate and the yield of product are higher. 

The next step involved cooling the reaction mixture to -196°C, removing the H2 at low pressure, and sealing the tube. This sealed tube was then used in the equilibrium measurements. When it warmed up, a fraction of the hydride complex reacted with benzene, yielding H2 and the phenyl complex, according to equilibrium 14.12. Therefore, the total amount of substance of H2 in equation 14.18 is given by the sum of the initial amount of substance of H2 (no) and the amount of substance of Sc(Cp )2Ph in equilibrium. The latter is easily calculated from the relative concentrations of Sc(Cp )2Ph and Sc(Cp )2H determined by H NMR, and the known initial concentration of Sc(Cp )2H (5.4 x 10-5x 1000/0.5 = 0.108 mol dm-3). To evaluate the initial amount of substance of H2, consider the experimental procedure before and after reaction 14.19 takes place. When this reaction occurs (at 25 °C) a certain amount of H2 remains in solution, and it can be calculated by an equation similar to 14.17. This amount will be equal to no, by assuming that (1) there is no further H2 solubilization when the tube is rapidly cooled to — 196 °C, and (2) only the H2 dissolved in the frozen reaction mixture is not removed by the evacuation procedure. 

Table 7.16 Calculated BDEs De (Do) (kcal/mol) of transition metal-methyl and metal-phenyl complexes. ...

Raag, R., Swanson, B. A., Poulos, T.L., and Ortiz de Montellano, P. R. (1990) Formation, crystal structure and rearrangement of a cytochrome P- iron-phenyl complex. Biochemistry 29, 8119-8126. 

An organometallic dioxygen adduct of an even more fleeting kind was observed in the reaction of the divalent chromium phenyl complex Tp > Cr-... 

Tetrakis(triethylphosphine)platinum(0) is extremely air sensitive and readily soluble in saturated aliphatic hydrocarbons. The complex can be stored under dry nitrogen in a freezer (-35°) for several months. The complex readily loses one of the coordinated phosphine molecules to give Pt(PEt3)36 (dissociation constant (K ) in heptane is 3.0 X 10" ). The H NMR spectrum measured in benzene-d6 shows two multiplets at 5 1.56 (CH2) and 1.07 ppm (CH3). Tetrakis-(triethylphosphine)platinum(O) is a strong nucleophile and reacts readily with chlorobenzene and benzonitrile to give a-phenyl complexes PtX(Ph)(PEt3)2 (X = Cl, CN).7 Oxidative addition of EtOH affords [PtH(PEt3)3] +. 

The decomposition of the phenyl complexes Ilia to chlorobenzenes and IV is first order and irreversible. Triphenylphosphine retards the rate of this decomposition, indicating that the decomposition pathway involves prior dissociation of triphenylphosphine from Ilia. The benzyl complexes Illb decompose both by rearrangement to lib and to the benzyl chlorides plus IV. The conversion of Illb to IV is irreversible, but it is not retarded by added triphenylphosphine. The p values for the decomposition of the phenyl complexes Ilia and the benzyl complexes Illb are also opposite in sign but low enough to fall in the range observed for radical reactions. 

Compounds containing chromium directly linked to a cyclosilanyl ring are not known so far. From hexacarbonylchromium and mono- or diphenylcyclopenta- and hexasilanes, however, the corresponding tricarbonylchromium r/ -phenyl complexes have recently been synthesized106 (Scheme 28). 

Reaction of Fe(OEC)Cl with phenylmagnesium bromide yields the o-phenyl complex Fe(OEC)Ph, the first example of an organometallic correlate [27]. 

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... 

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