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.
Roy
Partha
P
Department of Chemistry, Jadavpur University, Jadavpur, Kolkata 700 032, India.
Nandi
Mahasweta
M
Manassero
Mario
M
Riccó
Mauro
M
Mazzani
Marcello
M
Bhaumik
Asim
A
Banerjee
Pradyot
P
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