6533b7d2fe1ef96bd125e261

RESEARCH PRODUCT

Novel malonate-containing coordination compounds with ligands having N-And NO-donors: Synthesis, structures, and magnetic properties

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In our efforts to tune the structures of mixed-ligands malonate-containing coordination compounds, four copper(II) and two high-spin cobalt(II) complexes of formulas [Cu(mal)(H 2O)(dpo)] n (1), [Cu 2(mal) 2(H 2O) 2(dpp)] n · 7nH 2O (2), [Cu 2(mal) 2(H 2O) 2-(bpe)] n · 2nH 2O (3), {[Cu(mal) 2(H 2O) 2][Cu(dien)]} n · 4nH 2O (4)[Co 2(mal) 2(H 2O) 6(dpo)] ·2H 2O(5) and [Co(mal)(H 2O)(phen)] n · 2nH 2O (6) [H 2mal = malonic acid, dpo =4,4'-bipyridine-N,N'-dioxide, dpp = 2,3-bis(pyridyl)pyrazine, bpe =1,2-bis(4-pyridyl)ethylene, dien = diethylenetriamine and phen = 1,10-phenanthroline] have been synthesized and structurally characterized by X-ray diffraction on single crystals. Complexes 1, 2, 4, and 6 are chain compounds, 5 is a dinuclear species, and 3 has a sheet-like structure. The malonate ligand in this family acts as either a blocking (1 and 5) or bridging ligand (2-6). The rod-like molecules dpo (1 and 5) and bpe (3) exhibit the bis-monodentate (1 and 3) and monodentate (5) coordination modes, whereas dpp (2), dien (4), and phen (6) act as bis-bidentate (2), tridentate (4), and bidentate (6) ligands. The neutral motifs of 1-6 are interlinked through hydrogen bonds and weak C-H⋯ φ and φ-φ type interactions affording supramolecular three-dimensional networks. Variable-temperature magnetic susceptibility measurements show the occurrence of weak ferro-(2, 3, 5, and 6) and antiferromagnetic (1 and 4) interactions, the exchange pathways being the carboxylatemalonate (3-6), oxo-carboxylate (2), bis-bidentate (dpp) (2) or hydrogen bonds (1). Remarkably, the equatorial-Apical exchange pathway through the carboxylate bridge present in 4 provides the first case of the occurrence of an antiferromagnetic interaction in a malonate-containing copper(II) complex. © 2011 American Chemical Society.