Synthesis, crystal structure and catalytic activity of a novel Mo(VI)–oxazoline complex in highly efficient oxidation of sulfides to sulfoxides by urea hydrogen peroxide

Activation and Photoinduced Release of Alkynes on a Biomimetic Tungsten Center: The Photochemical Behavior of the W-S-Phoz System

The synthesis and structural determination of four tungsten alkyne complexes coordinated by the bio-inspired S,N-donor ligand 2-(4',4'-dimethyloxazoline-2'-yl)thiophenolate (S-Phoz) is presented. A previously established protocol that involved the reaction of the respective alkyne with the bis-carbonyl precursor [W(CO)2 (S-Phoz)2 ] was used for the complexes [W(CO)(C2 R2 )(S-Phoz)2 ] (R=H, 1 a; Me, 1 b; Ph, 1 c). Oxidation with pyridine-N-oxide gave the corresponding W-oxo species [WO(C2 R2 )(S-Phoz)2 ] (R=H, 2 a; Me, 2 b; Ph, 2 c). All W-oxo-alkyne complexes (2 a, b, c) were found to be capable of alkyne release upon light irradiation to afford five-coordinate [WO(S-Phoz)2 ] (3). The photoinduced release of the alkyne ligand was studied in detail by in situ 1 H NMR measurements, which revealed correlation of the photodissociation rate constant (2 b>2 a>2 c) with the elongation of the alkyne C≡C bond in the molecular structures. Oxidation of [WO(S-Phoz)2 ] (3) with pyridine-N-oxide yielded [WO2 (S-Phoz)2 ] (4), which shows highly fluxional behavior in solution. Variable-temperature 1 H NMR spectroscopy revealed three isomeric forms with respect to the ligand arrangement versus each other. Furthermore, compound 4 rearranges to tetranuclear oxo compound [W4 O4 (μ-O)6 (S-Phoz)4 ] (5) and dinuclear [{WO(μ-O)(S-Phoz)}2 ] (6) over time. The latter two were identified by single-crystal X-ray diffraction analyses.

Peroxoniobium(v)-catalyzed selective oxidation of sulfides with hydrogen peroxide in water: a sustainable approach

Facile and selective transformation of thioethers to the corresponding sulfoxides or sulfones with 30% H₂O₂ has been achieved in an aqueous medium by using peroxoniobium(v) complexes as reusable catalysts.

Aryl-substituted organomolybdenum(ii) complexes as olefin epoxidation catalysts

The epoxidation of selected olefins with a benzyl-substituted organomolybdenum complex and its fluorinated counterpart is described.

A new Mo Schiff base complex: methanol[N'-(3-meth-oxy-2-oxidobenzyl-idene)benzohydrazidato]dioxido-molybdenum(VI)

In the title benzil-idene Schiff base molybdenum(VI) complex, [Mo(C(15)H(12)N(2)O(3))O(2)(CH(3)OH)], the Mo(VI) ion is coordinated by two oxide O atoms and by two O atoms and one N atom of the tridentate N'-(3-meth-oxy-2-oxidobenzyl-idene)benzo-hydrazidate (L) Schiff base ligand. The methanol O atom completes the distorted octa-hedral configuration of the Mo(VI) atom. Strong O-H⋯N hydrogen bonds form a C(5) chain around a 2(1) screw axis. Weak C-H-O hydrogen bonds are also present.