240123-76-6Relevant academic research and scientific papers
Activation and Photoinduced Release of Alkynes on a Biomimetic Tungsten Center: The Photochemical Behavior of the W?S-Phoz System
Peschel, Lydia M.,Vidovi?, Carina,Belaj, Ferdinand,Neshchadin, Dmytro,M?sch-Zanetti, Nadia C.
, p. 3893 - 3902 (2019)
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)(C2R2)(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(C2R2)(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 1H 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 1H NMR spectroscopy revealed three isomeric forms with respect to the ligand arrangement versus each other. Furthermore, compound 4 rearranges to tetranuclear oxo compound [W4O4(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.
