872975-43-4Relevant articles and documents
From mono- and dinuclear to polynuclear cobalt(II) and cobalt(III) coordination compounds based on o-phthalic acid and 2,2′-bipyridine: Synthesis, crystal structures, and properties
Baca, Svetlana G.,Filippova, Irina G.,Ambrus, Christina,Gdaniec, Maria,Simonov, Yurii A.,Gerbeleu, Nicolae,Gherco, Olesea A.,Decurtins, Silvio
, p. 3118 - 3130 (2005)
The reaction of o-phthalic acid (H2Pht) and 2,2′- bipyridine (bpy) with cobalt(II) carbonate at different temperatures results in the isolation of three types of new cobalt(II) and cobalt(III) compounds. The mononuclear cobalt(III) complex [Co(CO3)(bpy)2] 2(Pht)·16H2O (1) is obtained when the reaction is run at 60°C. Crystallographic analysis revealed that 1 contains two crystallographically independent [Co(CO3)-(bpy)2] + cations, a Pht2- anion, and sixteen solvate water molecules. The latter form a wall of channels with the oxygen atoms of the carboxylate groups of the Pht2- anions, which are occupied by pairs of cations. Increasing the temperature of the reaction to 80°C leads to the formation of the open dinuclear cobalt(II) complex [(bpy)2Co(Pht) H(Pht)Co(bpy)2]-(HPht)(H2Pht)·2H2O (2), which crystallizes in two polymorphic modifications 2a and 2b. Compound 2a consists of a centrosymmetric dinuclear [(bpy)2Co(Pht)H(Pht)Co(bpy) 2]+ cation, an HPht- anion, an H2Pht molecule, and two solvate H2O molecules. In 2b, a small alteration in the crystal structure leads to an increase of the unit-cell volume. The asymmetric unit of 2b contains six crystallographically independent Co II complexes, which combine into four [(bpy)2Co(Pht)H(Pht) -Co(bpy)2]+ units. The main structural unit of the cyclic dinuclear complex [Co(Pht)(bpy)(H2O)]2·2H 2O (4) is neutral and cenrosymmetric, with the two CoII atoms linked by two phthalate ligands to form a 14-membered cycle. A further temperature increase results in the isolation of both the mononuclear complex [Co(Pht)(bpy)(H2O)3]·3H2O (3) and the polynuclear helical coordination polymer [Co(Pht)(bpy)-(H2O)] n (5). Extended hydrogen bonding networks as well as aromatic π-π stacking interactions stabilize multidimensional supramolecular architectures in all compounds. Magnetic susceptibility measurements have been performed for complexes 1, 2, 3, and 5. Simulations gave the following parameter sets: for complex 2 |D| = 70 cm-1, g = 2.55 and J = -0.1 cm -1; for complex 3 |D| = 80 cm-1, g = 2.6 and for complex 5 |D| = 65 cm-1, g = 2.45. Complex 1 is diamagnetic. Wiley-VCH Verlag GmbH & Co. KGaA, 2005.
