Double end-on azido derivative of a tridentate (NNO) Schiff base dimeric copper(II) complex: synthesis, X-ray structure, magnetic property and catalytic effectiveness

摘要

A dimeric copper(II) complex, bisf(2-[1-(aminoethylimino)ethyl]phenoxog-di-mu(1,1)-azido-dicopper(II), [Cu-2(L)(2)(mu(2-1,1)-N-3)(2)] (1) [L = 2[1-(aminoethylimino)ethyl]-phenoxo ion], has been isolated using a self-assembly reaction using a 1:1:1 molar ratio of Cu(NO3) 2 center dot 3H(2)O, HL and NaN3 in methanol at room temperature and characterized through X-ray diffraction analysis and spectroscopic studies. X-ray structural analysis reveals that 1 consists of two distinct dinuclear molecular units, where each copper(II) center in the individual dinuclear unit adopts a distorted square pyramidal geometry with a CuN4O chromophore ligated through a tridentate (NNO) Schiff base and two N atoms of two different bridging azides in mu(1,1)-mode. Two Cu(II) centers are linked through double mu(2)-1,1-N3 bridges to form the dinuclear unit [Cu-2(L)(2)(mu(2-1,1)-N-3)(2)]. In the crystalline state, the dinuclear units in 1 are associated through weak intermolecular N-H center dot center dot center dot O hydrogen bonds to afford a 2-D sheet structure viewed along the crystallographic a-axis. The small magnitude of the antiferromagnetic interaction (J = -0.45 cm(-1)) is a result of the long Cu center dot center dot center dot Cu separation (3.205(2) angstrom). The catalytic efficacy of 1 was studied in a series of solvents for the epoxidation of alkenes using tert-butylhydroperoxide (TBHP) as an efficient oxidant under mild conditions.