Novel Cage-Like Hexanuclear Nickel(II) Silsesquioxane. Synthesis, Structure, and Catalytic Activity in Oxidations with Peroxides

Abstract

New hexanuclear nickel(II) silsesquioxane [(PhSiO 1.5 ) 12 (NiO) 6 (NaCl)] (1) was synthesized as its dioxane-benzonitrile-water complex (PhSiO 1,5 ) 12 (NiO) 6 (NaCl)(C 4 H 8 O 2 ) 13 (PhCN) 2 (H 2 O) 2 and studied by X-ray and topological analysis. The compound exhibits cylinder-like type of molecular architecture and represents very rare case of polyhedral complexation of metallasilsesquioxane with benzonitrile. Complex 1 exhibited catalytic activity in activation of such small molecules as light alkanes and alcohols. Namely, oxidation of alcohols with tert-butylhydroperoxide and alkanes with meta-chloroperoxybenzoic acid. The oxidation of methylcyclohexane gave rise to the isomeric ketones and unusual distribution of alcohol isomers.

New Trends in Oxidative Functionalization of Carbon–Hydrogen Bonds: A Review

“…Polynuclear metal complexes containing voluminous organic [63,66,118,119,[129][130][131]186,[213][214][215][216][217][218][234][235][236][237][238][239][240][241] or siloxane [221][222][223][224][225][226][227][228] ligands are also very efficient in oxidations of organic compounds including saturated hydrocarbons with peroxides. For example, dinuclear copper complex 11 [221,224] and hexairon complex 15 (for the structure, see Figure 9) affording the products of cyclohexane oxidation in a very high yield of 46% (see Figure 10 [226]) can be considered as "inorganic models of methane monooxygenases."…”

“…This approach modeling natural enzymes can be called biomimetic route. Various polynuclear complexes [320][321][322] including siloxane derivatives [221][222][223][224][225][226][227][228] containing bulky ligands are especially attractive as catalysts in oxidations with peroxides. Bulky ligands around the reaction centers give rise in these cases to the selectivity enhancement [12,323].…”

“…Another hexairon complex 15 [226] (for the structure, see Figure 9) catalyzed the oxidation of cyclohexane affording the products in 46% yield (Figure 10), which is very high for oxidation of alkanes. Cations of cobalt and nickel gave cylinder-type complexes phenylsilsesquioxane [(PhSiO1,5)10(CoO)5(NaOH)] (compound 16) [227] and (PhSiO1.5)12(NiO)6(NaCl) (compound 17) [228]. Their "drum-like" structures are presented in Figures 11 and 12, respectively.…”

“…Compound 16 exhibited activity in catalytic highly stereoselective oxidation of 1,2-cyclohexane with m-CPBA ( Table 1). Cations of cobalt and nickel gave cylinder-type complexes phenylsilsesquioxane [(PhSiO 1,5 ) 10 (CoO) 5 (NaOH)] (compound 16) [227] and (PhSiO 1.5 ) 12 (NiO) 6 (NaCl) (compound 17) [228]. Their "drum-like" structures are presented in Figures 11 and 12 respectively.…”

Heptanuclear Cage CuII‐Silsesquioxanes: Synthesis, Structure and Catalytic Activity

“…Cage metallasilsesquioxanes were found to be active in alkene polymerization, epoxidation or epoxide ring opening, metathesis, hydroformylation, Ullmann–Goldberg condensation and amidation . Recently, significant attention was drawn to the potential of CLMS application in the homogeneous oxidation of C–H compounds with activity confirmed for Fe‐,, Cr‐, Ni‐, and Co‐based compounds. In turn, the best potential for this type of catalytic activity was found for Cu II ‐based cage silsesquioxanes.…”