Four mu4-oxo-bridged copper(II) complexes: magnetic properties and catalytic applications in liquid phase partial oxidation reactions.
Four copper(II) complexes, [Cu(4)(O)(L(n))(2)(CH(3)COO)(4)] with N(2)O-donor Schiff-base ligands, where HL(1) = 4-methyl-2,6-bis(cyclohexylmethyliminomethyl)phenol for complex 1, HL(2) = 4-methyl-2,6-bis(phenylmethyliminomethyl)phenol for complex 2 x CH(3)CN, HL(3) = 4-methyl-2,6-bis(((3-tri-fluoromethyl)phenyl)methyliminomethyl)phenol for complex 3, HL(4) = 4-methyl-2,6-bis(((4-tri-fluoromethyl)phenyl)methyliminomethyl)phenol for complex 4, were synthesized and characterized by elemental analysis, FT-IR, UV-vis spectroscopy and finally by single crystal X-ray diffraction study. X-Ray analysis reveals that all of these are mu(4)-oxo-bridged tetrameric copper(II) complexes. Four copper atoms arrange themselves around an oxygen atom tetrahedrally. Magnetic susceptibility measurements show the existence of very strong antiferromagnetic coupling among these ions (J = -210.1 to -271.3 cm(-1)), mediated by the oxygen atoms. Catalysis of the epoxidation of cyclohexene, styrene, alpha-methylstyrene and trans-stilbene by these complexes has been carried out homogeneously as well as heterogeneously by immobilizing the metal complexes over 2D-hexagonal mesoporous silica. The results obtained in both the catalytic conditions show that the olefins are converted to the respective epoxides in good yield together with high selectivity.
Department of Chemistry, Jadavpur University, Jadavpur, Kolkata 700 032, India.
Partha
P
Roy
Mahasweta
M
Nandi
Mario
M
Manassero
Mauro
M
Riccó
Marcello
M
Mazzani
Asim
A
Bhaumik
Pradyot
P
Banerjee
D000327:Adsorption; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D018360:Crystallography, X-Ray; D006861:Hydrogen Peroxide / Q000737:chemistry; D008280:Magnetics; D008958:Models, Molecular; D008968:Molecular Conformation; D009584:Nitrogen / Q000737:chemistry; D009609:Nitrous Oxide / Q000737:chemistry; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D010084:Oxidation-Reduction; D019800:Phenol / Q000737:chemistry; D012545:Schiff Bases / Q000737:chemistry; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet
D009942:Organometallic Compounds; D012545:Schiff Bases; D019800:Phenol; D003300:Copper; D006861:Hydrogen Peroxide; D009609:Nitrous Oxide; D009584:Nitrogen