TY - JOUR
T1 - π-π Interactions and magnetic properties in a series of hybrid inorganic-organic crystals
AU - González, M.
AU - Lemus-Santana, A. A.
AU - Rodríguez-Hernández, J.
AU - Knobel, M.
AU - Reguera, E.
PY - 2013/1
Y1 - 2013/1
N2 - The series of hybrid inorganic-organic solids T(Im) 2[Ni(CN) 4] with T=Fe, Co, Ni and Im=imidazole were prepared by soft chemical routes from aqueous solutions of the involved building units: imidazole, T 2 metal and the [Ni(CN) 4] 2- anionic block. The obtained samples were characterized from infrared and UV-vis spectroscopies, and thermogravimetric, X-ray diffraction and magnetic measurements. Anhydrous solids which crystallize with a monoclinic unit cell, in the I2/a space group with four formula units per cell (Z=4) were obtained. Their crystal structure was solved ab initio from the recorded X-ray powder patterns and then refined by the Rietveld method. The metal T is found with octahedral coordination to four N ends of CN groups and two imidazole molecules while the inner Ni atom preserves its planar coordination. The system of layers remains stacked in an ordered 3D structure through dipole-dipole and π-π interactions between imidazole rings from neighboring layers. In this way, a pillared structure is achieved without requiring the coordination of both nitrogen atoms from imidazole ring. The recorded magnetic data indicate the occurrence of a predominant ferromagnetic interaction at low temperature for Co and Ni but not for Fe. Such magnetic ordering is more favorable for Ni with transition temperature of 14.67 K, which was ascribed to the relatively high polarizing power for this metal. Within the considered T metals, to nickel the highest electron-withdrawing ability corresponds and this leads to an increase for the metal-ligand electron clouds overlapping and to a stronger π-π attractive interaction, two factors that result into a higher magnetic ordering temperature.
AB - The series of hybrid inorganic-organic solids T(Im) 2[Ni(CN) 4] with T=Fe, Co, Ni and Im=imidazole were prepared by soft chemical routes from aqueous solutions of the involved building units: imidazole, T 2 metal and the [Ni(CN) 4] 2- anionic block. The obtained samples were characterized from infrared and UV-vis spectroscopies, and thermogravimetric, X-ray diffraction and magnetic measurements. Anhydrous solids which crystallize with a monoclinic unit cell, in the I2/a space group with four formula units per cell (Z=4) were obtained. Their crystal structure was solved ab initio from the recorded X-ray powder patterns and then refined by the Rietveld method. The metal T is found with octahedral coordination to four N ends of CN groups and two imidazole molecules while the inner Ni atom preserves its planar coordination. The system of layers remains stacked in an ordered 3D structure through dipole-dipole and π-π interactions between imidazole rings from neighboring layers. In this way, a pillared structure is achieved without requiring the coordination of both nitrogen atoms from imidazole ring. The recorded magnetic data indicate the occurrence of a predominant ferromagnetic interaction at low temperature for Co and Ni but not for Fe. Such magnetic ordering is more favorable for Ni with transition temperature of 14.67 K, which was ascribed to the relatively high polarizing power for this metal. Within the considered T metals, to nickel the highest electron-withdrawing ability corresponds and this leads to an increase for the metal-ligand electron clouds overlapping and to a stronger π-π attractive interaction, two factors that result into a higher magnetic ordering temperature.
KW - 2D solids
KW - Crystal structure
KW - Hybrid inorganic-organic solids
KW - Magnetic properties
UR - http://www.scopus.com/inward/record.url?scp=84866918166&partnerID=8YFLogxK
U2 - 10.1016/j.jssc.2012.08.026
DO - 10.1016/j.jssc.2012.08.026
M3 - Artículo
SN - 0022-4596
VL - 197
SP - 317
EP - 322
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
ER -