μ-BENZENE-1,2,4,5-TETRACARBOXYLATO-κ2O1:O4)BIS-[AQUA-BIS-2-(AMINOMETHYL) PYRIDINE-κ2N,N’) NICKEL (II)] DECAHYDRATE: STRUCTURE AND MAGNETIC PROPERTIES

Abstract

Benzene-1,2,4,5-tetracarboxylato-2 O 1 :O 4)bis-[aqua-bis-2-(aminomethyl) pyridine-2 N,N') nickel (II)] decahydrate, [Ni 2 (amp) 4 (btc)(H 2 O) 2 ] 10H 2 O has been synthesized and its crystal structure determined by X-ray diffraction. The complex crystallizes in the Monoclinic space group P2 1 /n with cell dimensions a= 11.0102 (10) Å, b= 21.5416 (19) Å, c= 11.0445 (10) Å and = 118.753 (1)°, and two formula units per cell (Z= 2, Z'= 0.5). The structure consists of centrosymmetric dimeric units in which the benzene tetracarboxylate anions (btc) bridge the symmetry-related nickel (II) cations, two bidentate chelating molecules of 2-(aminomethyl) pyridine and a terminal aqua ligand completing the six-fold coordination at each metal. These dimers link to each other via H-bonding to form chains parallel to [100], while the water solvates form a strongly bound 2D network parallel to (100), made up by small (R 4 4 (8)) and large (R 20 20 (40)) rings, the latter ones "pierced" by the chains of dimmers, with a profuse H-bonding interconnection between both substructures. Magnetic susceptibility measurements as a function of temperature disclose weak interdimeric exchange interactions. Fitting of these data to a dimeric model yields J=-3.5 cm-1 and g= 2.13.