A three-dimensional copper(II) 12-metallacrown-4 complex with malonomonohydroxamic acid (H(3)mmh) as a ligand

作者：Lago Ana B; Pasan Jorge; Canadillas Delgado Laura; Fabelo Oscar; Casado Francisco J M; Julve Miguel; Lloret Francesc; Ruiz Perez Catalina^*

来源：New Journal of Chemistry, 2011, 35(9): 1817-1822.

DOI：10.1039/c1nj20184k

Slow diffusion of an ethanolic solution of copper(II) into an aqueous solution of partially deprotonated malonodihydroxamic acid (H(4)mdh) affords the pentanuclear complex of formula {[K(H2O)(2)](2)[Cu-5(mmh)(4)]}(n) (1) (H(3)mmh = malonomonohydroxamic acid) which is formed by 12-MC-4 metallacrown units with the fifth copper(II) ion being placed at the center of the square metallacrown unit. The dianionic pentacopper(II) planar entity interacts with diaquapotassium(I) counterions through the carboxylate-oxygen atoms resulting in a neutral three-dimensional structure. Magnetic susceptibility measurements in the temperature range 1.9-300 K for 1 show the occurrence of relatively strong antiferromagnetic interactions within the pentanuclear copper(II) core leading to two degenerated low-lying spin doublets at T < 50 K. X-band EPR spectra at low temperatures give additional support to the ground spin doublet nature. The topology of the pentanuclear copper(II) unit of 1 together with good ability to mediate magnetic interactions between the copper(II) ions of the diatomic N-O(oximato) and monoatomic O(oximato) bridges which connect the metal centers within the pentanuclear core account for this magnetic behaviour.

• 出版日期2011