- Preparation and crystal structure of an oxoimido complex of molybdenum containing the 2,4,6-triphenylphenylimide ligand
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Reaction of 2,4,6-triphenylaniline with Na2MoO4 in the presence of SiMe3Cl and NEt3 in 1,2-dimethoxyethane (dme) gave the oxoimido complex [MoCl2(NC6H2Ph3-2,4,6)O(dme)]. Its crystal structure determination showed a distorted octahedron with mutually cis-oxo and imido groups, trans-chloride ligands and the dme oxygen atoms trans to the oxide and imide ligands. The Mo-Nimido and Mo-Ooxo bond lengths [1.756(7) and 1.700(6) A] are consistent with four- and two-electron donor ligands, respectively. The phenyl ring of the imide ligand orientates with the face of one ortho substituent phenyl ring pushing away from a chloride ligand and tilted towards the oxide ligand. The second such phenyl ring tilts away from a chloride ligand but does not push away from the side of the molecule. This occurs as the imido group bends towards the other side of the molecule [Mo-N-C 172.2(7)°] and a methyl group of the dme ligand is severely distorted to remove an interaction with the phenyl ring.
- Clark, George R.,Nielson, Alastair J.,Rickard, Clifton E. F.
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- Cobalt schiff base complex-catalyzed oxidation of anilines with tert-butyl hydroperoxide
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Cobalt Schiff base complexes [Co(SB)] catalyze the oxidation of anilines (1) with tert-butyl hydroperoxide to give nitrobenzenes 2 and 4-(tert-butylperoxy)-2,5-cyclohexadien-1-imine derivatives 3 in yield distributions depending on the substitution mode of the substrate. 4-Alkyl- and 4-aryl-2,6-di-tert-butylanilines gave mixtures of 2 and 3, where the higher the bulkiness of the 4-substituent, the higher the yield of 2. With 2,4,6-trimethylaniline, the ratio of oxidations of the nitrogen and C-4 atoms was almost the same; but a hydrolyzed product 5 of the imine was obtained. 2,4,6-Triphenylaniline gave only 2. Nitrobenzene derivatives were also obtained from 2,6-dialkylanilines and 4-substituted anilines. The catalytic activity of Co(SB) depended on the nature of the SB ligand: the formal potential E° and steric factors seem to affect the reaction rate. Kinetic studies showed that the key step may involve hydrogen abstraction from the aniline, presumably by t-BuO? generated from homolytic decomposition of initially formed CoIII(SB)(OO-t-Bu). A precursor of 2 was found to be the nitrosobenzene derivative.
- Foerster, Stefan,Rieker, Anton,Maruyama, Kazushige,Murata, Kunihiko,Nishinaga, Akira
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p. 3320 - 3326
(2007/10/03)
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- Co(salen) catalyzed oxidation of 2,4,6-trisubstituted anilines with tert-butylhydroperoxide
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Co(salen) catalyzed oxidation of 2,4,6-trisubstituted (preferentially 2,6-di-tert-butylated) anilines with tert-butylhydroperoxide gives 4-tert-butylperoxy-2,5-cyclohexadien-1-imine and nitrobenzene derivatives. The relative ratio of the products depends on the nature of the substituents in the substrate.
- Nishinaga,Forster,Eichhorn,Speiser,Rieker
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p. 4425 - 4428
(2007/10/02)
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