Design of 1D and 2D molecule-based magnets with the ligand 4,5-dimethyl-1,2-phenylenebis(oxamato)

Abstract

Three new bimetallic oxamato-based magnets with the proligand 4,5-dimethyl-1,2-phenylenebis(oxamato) (dmopba) were synthesized using water or dimethylsulfoxide (DMSO) as solvents. Single crystal X-ray diffraction provided structures for two of them: [MnCu(dmopba)(H₂O)₃]_n·4nH₂O (1) and [MnCu(dmopba)(DMSO)₃]_n·nDMSO (2). The crystalline structures for both 1 and 2 consist of linearly ordered oxamato-bridged Mn^IICu^II bimetallic chains. The magnetic characterization revealed a typical behaviour of ferrimagnetic chains for 1 and 2. Least-squares fits of the experimental magnetic data performed in the 300–20 K temperature range led to J_MnCu = −27.9 cm⁻¹, g_Cu = 2.09 and g_Mn = 1.98 for 1 and J_MnCu = −30.5 cm⁻¹, g_Cu = 2.09 and g_Mn = 2.02 for 2 (H = −J_MnCu∑S_Mn,_i(S_Cu,i + S_Cu,_i−1)). The two-dimensional ferrimagnetic system [Me₄N]_2n{Co₂[Cu(dmopba)]₃}_n·4nDMSO·nH₂O (3) was prepared by reaction of Co^II ions and an excess of [Cu(dmopba)]²⁻ in DMSO. The study of the temperature dependence of the magnetic susceptibility as well as the temperature and field dependences of the magnetization revealed a cluster glass-like behaviour for 3.