P-Oxo compounds

Iron in the oxidation state + III in dimeric p-oxo compounds 5 can be reduced to iron + II, leading to monomeric phthalocyanines 6.351... 

The reaction of LilfCsFL CF ] with CpTiCl3 gives the binuclear complex (CpTiC IXCsFL CF ], which on treatment with Mg/Hg is reduced to the corresponding Ti(m)-Ti(iii) derivative (CpTiCl lXCsFL CF ] it is converted to the p-oxo compound (CpTiCl KCsFL CF K/x-O) when exposed to air.1053... 

Sturtz, G., Elimination-addition reactions of P-halo-P-ethylenic phosphonates. Obtaining of P-oxo compounds. Bull. Soc. Chim. Fr., 1345, 1967. 

I. r. and Raman data are now available for (C6F,)3Sb and the dichloride and bromide,"" and structural studies have been reported for three p,-oxo-compounds (Me3SbX)20 (X = Cl, CIO4, or N3)."" All three species have no symmetry and are extensively disordered, but the antimony atoms have distorted trigonal-bipyramidal co-ordination. In the chloride and perchlorate, however, these groups... 

Often, bis(p-oxo) copper compounds are stabilized by didentate ligands generating square planar Cu (0)2 complexes favorable for d copper(III) ion (1). Removal of a third nitrogen donor often can change the dioxygen adduct produced from a side-on peroxo isomer to a bis(p-oxo) compound. For example, the copper(I) complex of the tridentate pyridyl amine ligand. 

R3 = Bz-d2). Although didentate ligands prefer Cu2 -(p-oxo)2 compounds, adding one methyl group on the 6-position of the pyridine moiety (changing R1 from H to Me) shifts the equilibrium from a bis(p-oxo)compound in [ Cu ( Pyl ) 2(0 )2] to a side-on peroxo dicopper(II) compound... 

More recently, this aromatic hydroxylation reaction has been examined in greater detail by rR spectroscopy and with a nitro-substituted XYL-H derivative. The relative rate of the hydroxylation reaction of [Cu2(N02-XYL-H)] is diminished compared to formation of the peroxo intermediate [Cu2 (N02-XYL-H)(02)], making the latter accessible to spectroscopic analysis 109). The oxygenated product [Cu2 (N02-XYL-H)(02)] " has UV-VIS absorption bands at 358nm (s = 20,000 cmand 530 nm (e = 1,200 M cm ), similar to other side-on peroxo dicopper(II) complexes, but it also has an additional intense peak at 435 nm (s = 5,000 M cm ). Despite the tendency for certain side-on peroxo compounds to be in equilibrium with isomeric bis(p-oxo) compounds (see above), which also have LMCT transitions near 400-420 nm, this new peak is not due to the presence of a bis(p-oxo) species. With resonance excitation, no symmetric Cu2 (0)2 core stretching mode was observed near 600 cm H7). Instead, a rR profile of the 435 nm absorption band shows that it is associated with the 277 cm peak associated assigned as the side-on peroxo Cu... Cu stretch. As determined by comparison with a known bis(p-oxo) standard, the amount of residual Cu2 (0)2 possibly in equilibrium was determined to be 0.13 % (0.0013) relative to the amount of Cug-(side-on-02) present. 

Dihydroquinazolines are normally stable compounds but they deteriorate on long standing. Some examples are known to oxidize to the corresponding 4(3H)quinazolinones. 3-Methyl-3,4-dihydroquin-azoline is converted to the 4-oxo compound after three recrystallizations from light petroleum. The most remarkable example is 3,4-dihydro-6-fluoro-3(p-fluorophenyl)quinazoline [(44), R = F] which oxidizes at its melting point (137°-I38°C), Other halogenated derivatives of (44) are more stable. ... 

The spectra of 1,3,5-, 1,3,7-, and 1,3,8-triazanaphthalerie cations revealed that they were predominantly hydrated, and mild oxidation to the corresponding 4-oxo compounds indicated that hydroxylation took place on C-4. Ring-chain tautomerism in the cation was excluded, at least during the first 45 min after mixing, because negative aldehyde tests were obtained with p-nitrophenylhydrazine. 1,3,6-Triazanaphthalene, under the same conditions, gave a yellow precipit-... 

In the case of iron-containing small molecule analogs of Mb and Hb a much rockier road to successful model compounds was encountered. Even though the syntheses of iron porphyrin complexes were carried out in analogous manner to the cobalt species described above, their irreversible oxidation to the p-oxo dimer upon... 

In summary, researchers have found a number of methods for avoiding p-oxo dimer formation and preserving a five-coordinate Fe(II) in iron-containing model compounds, through ... 

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