Polynuclear complexes of macrocyclic oxamide with 5-sulfosalicylate: syntheses, crystal structures and magnetic properties

Abstract

Hydrothermal reactions of mixed ligands 5-sulfosalicylic acid (H₃SSAL) and macrocyclic oxamide complex (CuL) with M(ClO₄)₂·6H₂O (M = Mn, Gd and Cu) afford three new complexes, including [Mn^II₂Mn^III(SSAL)₂(CuL)₂(OH)(H₂O)₃]n (1), {[Gd₂(HSSAL)₂(CuL)₄(C₂O₄)(H₂O)₂]·2H₂O}_n (2) and [Cu₂(HSSAL)₂(CuL)₄]·2H₂O (3) (CuL, H₂L = 2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-diene). Complex 1 has very interesting mixed-valence manganese-copper Cu^IIMn^IIMn^IIIMn^IICu^II units and consists of a 1D ladderlike chain formed by the linkage of copper(II) and Mn₃ clusters via the oxamide and SSAL³⁻ bridges. The structure of 2 consists of hexanuclear Cu^II₄Gd^III₂ molecules and is arranged in a 1D ladderlike chain formed by the linkage of copper(II) and gadolinium(III) via the oxamide, oxalate and HSSAL²⁻ bridges. Complex 3 is a hexanuclear Cu^II₆ molecule including both oxamide and HSSAL²⁻ bridges. The results of magnetic determination show pronounced antiferromagnetic interactions in 1 and 3, and ferromagnetic interactions in 2.