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

摘要

The square-planar complex [Cu(MIMH)(CH_3CO_2)](ClO_4)(1)(MIMH = [(4-methylimidazol-5-yl)methylene]histamine) was prepared and structurally characterized. Complex 1 crystallizes in the monoclinic space group P2_1 with a = 10.5331(10), b = 12.6177(10), c = 12.9773(10) A, #beta# = 107.710(10) deg, V = 1643.0(2) A~3, and Z = 4. Single-crystal X-ray analysis reveals that the copper(II) atom in 1 has a distorted square-planar environment defined by three nitrogen atoms from the Schiff base ligand and one oxygen atom from the acetate group. The Cu-N bond lengths range from 1.950(3) to 2.015(3) A and the Cu-O(1) bond length is 1.952(2) A. The electronic spectra of 1 in aqueous solutions indicates that 1 forms adducts of square-pyramidal geometry with H_2O. Cyclic voltammetry of 1 in DMF solution shows that there is some degradation of 1 upon reduction.