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Trinuclear Dioxidomolybdenum(VI) Complexes of Tritopic Phloroglucinol‐Based Ligands and Their Catalytic Applications for the Selective Epoxidation of Olefins
Author(s) -
Maurya Mannar R.,
Tomar Reshu,
Rana Lata,
Avecilla Fernando
Publication year - 2018
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.201800440
Subject(s) - chemistry , stereochemistry , crystal structure , metal , catalysis , nuclear magnetic resonance spectroscopy , ligand (biochemistry) , octahedron , molybdenum , crystallography , inorganic chemistry , organic chemistry , biochemistry , receptor
Four trinuclear dioxidomolybdenum(VI) complexes, [{Mo VI O 2 (H 2 O)} 3 ptk(bhz) 3 ] ( 1 ), [{Mo VI O 2 (H 2 O)} 3 ptk(fah) 3 ] ( 2 ), [{Mo VI O 2 (H 2 O)} 3 ptk(inh) 3 ] ( 3 ), and [{Mo VI O 2 (H 2 O)} 3 ptk(nah) 3 ] ( 4 ), based on the tritopic central 2,4,6‐triacetylphloroglucinol (H 3 ptk) ligands H 6 ptk(bhz) 3 ( I ), H 6 ptk(fah) 3 ( II ), H 6 ptk(inh) 3 ( III ) and H 6 ptk(nah) 3 ( IV ) (Hbhz = benzoylhydrazide, Hfah = 2‐furanoylhydrazide, Hinh = isonicotinoylhydrazide and Hnah = nicotinoylhydrazide), respectively, are presented. All of the synthesized ligands, as well as their complexes, have been characterized by elemental, thermal, and electrochemical analyses, spectroscopic techniques (FTIR, UV/Vis, 1 H and 13 C NMR), and single‐crystal X‐ray studies of [{Mo VI O 2 (H 2 O)}{Mo VI O 2 (MeOH)} 2 ptk(bhz) 3 ] · 2H 2 O · 1.25MeOH ( 1a ) and [{Mo VI O 2 (EtOH)} 3 ptk(fah) 3 ] · 3EtOH ( 2a ). Each pocket of the ligands coordinates in a dibasic tridentate fashion through two oxygen atoms and one nitrogen atom to each metal center. Due to the presence of tridentate binding pockets in the ligands, each metal center conserves its octahedral structure by coordinating with water molecules in the synthesized complexes or by other solvent(s) in the crystal structures. These complexes were evaluated for the epoxidation of terminal and internal alkenes in the presence of H 2 O 2 using NaHCO 3 as a promoter. Under the optimized reaction conditions, all alkenes were converted to the corresponding epoxides selectively in good yield and high turnover number.