Catalytic activity of nickel(II), copper(II) and oxovanadium(II)‐dihydroindolone complexes towards homogeneous oxidation reactions. (11th January 2018)

• Record Type: Journal Article
• Authors: Adam, Mohamed Shaker S.
• Is Part Of: Applied organometallic chemistry. Volume 32:Number 4(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-01-11
• Subjects: catalysis -- complexes -- copper(II) -- Dihydroindolone -- hydrogen peroxide -- nickel(II) -- oxidation -- oxovanadium(II); Organometallic chemistry -- Periodicals; Organometallic compounds -- Periodicals; 547.05
• DOI: 10.1002/aoc.4234
• Languages: English
• ISSNs: 0268-2605

Abstract

Abstract : Three novel paramagnetic metal complexes (MH2 ID) of Ni 2+, Cu 2+ and VO 2+ ions with 3‐hydroxy‐3, 3'‐biindoline‐2, 2'‐dione (dihydroindolone, H4 ID) were synthesized and characterized by different spectroscopic methods. The ligand (H4 ID) was synthesized via homocoupling reaction of isatin in presence of phenylalanine in methanol. Complexation of low valent Ni 2+, Cu 2+ ions and high valent VO 2+ ions with H4 ID carried out in 1: 2 molar ratios. A comparison in the catalytic potential of paramagnetic complexes of low and high valent metal ion was explored in the oxidation processes of cis ‐cyclooctene, benzyl alcohol and thiophene by an aqueous H2 O2, as a green terminal oxidant, in the presence and absence of acetonitrile, as an organic solvent, at 85 °C. NiH2 ID, CuH2 ID and VOH2 ID show good catalytic activity, i.e. good chemo‐ and regioselectivity. VOH2 ID has the highest catalytic potential compared to both Ni 2+ ‐ and Cu 2+ ‐species in the same homogenous aerobic atmosphere. Catalytic oxidation of other alkenes and alcohols was also studied using NiH2 ID, CuH2 ID or VOH2 ID as a pre‐catalyst by an aqueous H2 O2 . A mechanistic pathway for those oxidation processes was proposed. Abstract : Three novel complexes of Ni 2+, Cu 2+ and VO 2+ ions with dihydroindolone were synthesized and characterized. The catalytic efficiency of Ni‐, Cu‐ and VO‐complex was measured in the redox processes of cis ‐cyclooctene, benzyl alcohol and thiophene by an aqueous H2 O2 in acetonitrile or under solvent‐free conditions. VO‐complex is more effective catalyst than Ni‐ and Cu‐complexes. The more Lewis acid character and the high oxidation number of the V 4+ /V 5+ ions could be the main reasons for that higher catalytic potential. Under solvent‐free conditions, the catalytic processes are less sufficient compared to that in acetonitrile with all complex catalysts. The catalytic potential of Ni‐, Cu‐ and VO‐complexes was investigated in redox processes of various aliphatic or cyclic alkenes and alcohols. A short mechanistic pathway of the catalytic redox process is presented involving electron and oxygen transfers.