Synthesis, crystal structure and ferro-magnetic interaction of a binuclear copper(II) complex with the 1,4-dinitro-2,3,5,6-tetracarboxylatobenzenic anion as bridging ligand

Abstract

A binuclear complex [Cu 2 (DTB)(DMF) 4 (H 2 O)] AE 2DMF (DTB ¼ 1,4-dinitro-2,3,5,6-tetracarboxylatobenzenic anion; DMF ¼ N,N-dimethylformamide) has been synthesized and its crystal structure determined by X-ray crystallography. In the complex Cu ion is located in a distorted square pyramidal environment with two oxygen atoms O(1) and O(3) from two carboxylate groups, another two oxygen atoms O(7) and O(8) from terminal ligands of two DMF molecules, and a fifth coordinated oxygen atom O(9) from the terminal ligand of one H 2 O molecule, in which the O(8) atom is situated in the apex of the pyramid. DTB as bridging ligand coordinates two Cu ions through its four carboxylate groups. The variable-temperature magnetic susceptibility of the complex was measured in the 5-300 K range. The magnetic coupling parameter is consistent with a ferromagnetic exchange between the two copper(II) centers and the data fit a binuclear magnetic exchange model based on the Hamiltonian operator (Ĥ ¼ )2JŜ 1Ŝ2 ,Ŝ 1 ¼Ŝ 2 ¼ 1/2), giving the ferromagnetic coupling parameter of 2J ¼ 1.80 cm )1 . This is the first example of a tetracarboxylatobenzenic bridging complex exhibiting ferromagnetic interaction.

Two nickel(II) bis[(pyridin-2-yl)methyl]amine complexes with homophthalic and benzene-1,2,4,5-tetracarboxylic acids

“…SALTIJ (Shi et al, 2004)] and one with Co (GEFGAA; Xia et al, 2006). From a metrical point of view, there are no substantial differences between the Ni1 (in substructure C) and Ni2 (in substructure S) coordination polyhedra (Table 4), or that in (I), with ranges of coordination lengths and angles (listed for substructures C and S, respectively) as follows: N/O-Ni = 2.0437 (12)-2.1241 (13) and 2.0448 (13)-2.0995 (15) Å ; cis angles = 80.95 (6)-95.65 (6) and 80.70 (6)-96.25 (6) ; trans angles = 168.58 (6)-177.01 (5) and 170.22 (6)-176.31 (6) .…”