Synthesis, structure, and redox properties of the molybdenum(VI) complexes [Mo(δ5-C5Ph4R)O2X] (R = 2,5-dimethoxyphenyl; X = Br or alkoxide)

Redox and Lewis Acid Reactivity of Unsaturated OsII

“…Reaction (1:1 O 2 /Os) of these reagents occurs in time of mixing at 25°C with a color change from green to yellow to give complete conversion (Scheme 1) to a benzene-soluble diamagnetic product 6 of C 2v symmetry ( 1 H and 31 P NMR evidence). The CI (methane) mass spectrum of the isolated product shows [(PNP) OsO 2 ] + as the highest mass, supporting a formula (PNP)OsO 2 I for 6, which, together with the C 2v symmetry, would require full scission of the O/O bond (i.e., a rare 4-electron redox change) [17][18][19] or, if iodide were not coordinated, then a salt of the cation (PNP)OsO 2 + . Crystals grown by cooling from toluene were determined by X-ray diffraction (Figure 2) Scheme 3 (see also Supporting Information) shows relative DFT(B3LYP) electronic energies (corrected for solvation using a self-consistent reaction field based on numerical solutions of the Poisson-Boltzmann equation) of a variety of candidate intermediates; bold arrows map the lowest energy intermediates for what is seen to be a highly exothermic process.…”

Oxidation of [CpMo(CO)3R] olefin epoxidation precatalysts with tert-butylhydroperoxide

“…For the sake of relevance of Mo@O group in epoxidation catalysis, and based on the evidence that Cp and R ligands are not lost during catalysis[38], the theoretical Mo(IV) species I 0 has been formulated as [CpMo(O)R].Scheme 1 illustrates the energy profile for the fate of mono oxo species I 0 . This species may be stabilized through the coordination of solvent (CH 3 OH, H 2 O), substrate olefin or O-donor TBHP[58][59][60][61][62].…”

High oxidation state organomolybdenum and organotungsten chemistry in protic environments

“…Thus, compound [(C 5 Ph 4 (2,5-C 6 H 3 (OMe) 2 ))MoO 2 (OMe)] leads to a mixture of products, some of which could not be characterized, when treated with water, acetic acid, or 4-methoxyphenol. However, all these reactions yielded variable amounts of the free cyclopentadiene, C 5 Ph 4 (2,5-C 6 H 3 (OMe) 2 )H, this being isolated in high yields when using a large excess of water in the reaction [87]. Loss of this ring has also been observed during catalytic cyclooctene epoxidation.…”

“…The cyclic Mo V derivative obtained with ArSi(OH) 3 , on the other hand, can be easily oxidized to an acyclic Mo VI product. The Mo-Br bond in compound [(C 5 Ph 4 (2,5-C 6 H 3 (OMe) 2 ))MoO 2 Br] is protonolyzed by aliphatic alcohols (but not phenols) to generate the corresponding [(C 5 Ph 4 (2,5-C 6 H 3 (OMe) 2 ))MoO 2 (OR)] [87].…”

“…3 Cl] [86] and [(C 5 Ph 4 (2,5-C 6 H 3 (OMe) 2 ))MoO 2 Br] from [(C 5 Ph 4 (2,5-C 6 H 3 (OMe) 2 ))Mo(CO) 3 Br] [87]. The oxidation strategy has recently been made more convenient and general by the use of TBHP in place of O 2 , leading to the preparation of [(C 5 H 4 R)MoO 2 Cl] from [(C 5 H 4 R)Mo(CO) 3 Cl] (R = H, Me, Bz) [88].…”