Synthesis, Crystal Structure, Magnetic, Thermal and Fluorescent Properties of [Co(H₂O)₄(nia)₂](suc)·(H₂suc)

Abstract

A new cobalt(II) complex, [Co(H 2 O) 4 (nia) 2 ](suc)·(H 2 suc) [nicotinamide = nia, succinate = suc 2− ], has been synthesized and characterized by elemental analysis, IR, TG-DTA and single-crystal X-ray diffraction. It contains [Co(H 2 O) 4 (nia) 2 ] 2+ complex cations, uncoordinated suc 2− anios and H 2 suc species. In the complex cation the cobalt(II) ion is coordinated by four aqua and two nia ligands in a distorted octahedral geometry. The suc 2− dianion acts as a counter-ion, while H 2 suc is present as a molecule of solvation. A three-dimensional network is formed by O-H···O and N-H···O hydrogen bonds. The title complex exhibits luminescence in the solid state at room temperature. The magnetism of the complex was studied over the temperature range 1.8 -300 K.

Structural and magnetic properties of cobalt(II) complexes with pyridinecarboxamide ligands

“…The corresponding effective moment is l eff = 4.6 BM for 1 and 4.9 BM for 2. These values are similar to the measured effective magnetic moment of some other cobalt complexes [17,31] at room temperature. The Curie-Weiss temperatures are both negative and relatively small (h = À9.4 K for 1 and À1.7 K for 2).…”

“…The Curie-Weiss temperatures are both negative and relatively small (h = À9.4 K for 1 and À1.7 K for 2). The obtained non-zero values of the Curie-Weiss temperatures very probable just reproduces the decrease of the product v ⁄ T with lowering temperature due to the spin-orbit coupling rather than the weak antiferromagnetic interaction as for example observed in [17]. The isothermal magnetization of both samples measured at 5 K is shown in Fig.…”

“…There are also some complexes with the same ligands (nicotinamide and water molecules) bonded to Co 2+ ion and different uncoordinated ions like chloride [16], succinate [17] and phthalate [18] in the structure. These anions are hydrogen bonded to the complex.…”