Synthesis, crystal structure and properties of square-planar acetato{[(4-methylimidazol-5-yl)methylene] histamine}copper(II) perchlorate

The square-planar complex [Cu(MIMH)(CH3Co2)](ClO4) (1) (MIMH = [(4-methylim idazol-5-yl)methylene]histamine) was prepared and structurally characterize d. Complex 1 crystallizes in the monoclinic space group P2(1)/n with a = 10 .5331(10), b = 12.6177(10), c = 12.9773(10) Angstrom, beta = 107.710(10)deg rees, V = 1643.0(2) Angstrom(3), and Z = 4. Single-crystal X-ray analysis r eveals that the copper(II) atom in 1 has a distorted square-planar environm ent defined by three nitrogen atoms from the Schiff base ligand and one oxy gen atom from the acetate group. The Cu-N bond lengths range from 1.950(3) to 2.015(3) Angstrom and the Cu-O(1) bond length is 1.952(2) Angstrom. The electronic spectra of 1 in aqueous solutions indicates that 1 forms adducts of square-pyramidal geometry with H2O. Cyclic voltammetry of 1 in DMF solu tion shows that there is some degradation of 1 upon reduction.