Tuning the Structural and Magnetic Properties of Thermally Robust Coordination Polymers

• Published in: Inorganic chemistry 2006-09, Vol.45 (19), p.7612-7620
• Main Authors: Masciocchi, Norberto, Galli, Simona, Sironi, Angelo, Cariati, Elena, Galindo, Miguel A, Barea, Elisa, Romero, Ma Angustias, Salas, Juan M, Navarro, Jorge A. R, Santoyo-González, Francisco
• Format: Article
• Language: English
• ISSN: 0020-1669; 1520-510X
• DOI: 10.1021/ic0602188

Thermally robust materials of the M(5-X-pyrimidin-2-olate)2 type [M = Co, X = Cl (1 Cl ), X = Br (1 Br ), X = I (1 I ); M = Zn, X = Cl (2 Cl ), X = Br (2 Br ), X = I (2 I )] have been synthesized. Their X-ray powder diffraction structural characterization has revealed that they crystallize as I4̄2d diamondoid frameworks, isomorphous to those of the pristine [M(pyrimidin-2-olate)2] n analogues (1 H , M = Co; 2 H , M = Zn). The magnetic measurements of the 1 X series at magnetic fields of 100, 300, and 5000 Oe reveal a weak ferromagnetic ordering taking place below the Néel temperature (T N ∼ 20 K), arising from spin canting phenomena of the antiferromagnetically coupled cobalt centers. Moreover, magnetic hysteresis studies carried out on the 1 X series at 2 K reveal a strong dependence of both the coercive field H coer (2500, 1000, 775, and 500 Oe for 1 Br , 1 Cl , 1 I , and 1 H , respectively) and the remnant magnetization M rem (0.0501 μB for 1 Br and 1 Cl , 0.0457 μB for 1 I , and 0.0358 μB for 1 H ) on the 5-substituent of the pyrimidin-2-olates. The molecular alloys [Co(5-Y-pyrimidin-2-olate)2] (Y = Cl/Br, 1 Cl/Br ) and [Co(5-Y‘-pyrimidin-2-olate)2] (Y‘ = Br/I, 1 Br/I ) have also been prepared and characterized, proving that they have intermediate properties. These materials combine interesting functional properties, such as chemical inertness, magnetism, photoluminescence, and (although weak) SHG activity.