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

Autor: Nicolae Gerbeleu, Silvio Decurtins, Maria Gdaniec, Christina Ambrus, I. G. Filippova, Svetlana G. Baca, Olesea A. Gherco, Yurii A. Simonov
Rok vydání: 2005
Předmět:
Zdroj: European Journal of Inorganic Chemistry. 2005:3118-3130
ISSN: 1099-0682
1434-1948
DOI: 10.1002/ejic.200500008
Popis: The reaction of o-phthalic acid (H 2 Pht) 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(CO 3 )(bpy) 2 ] 2 (Pht).16H 2 O (1) is obtained when the reaction is run at 60 °C. Crystallographic analysis revealed that 1 contains two crystallographically independent [Co(CO 3 )-(bpy) 2 ] + cations, a Pht 2 - anion, and sixteen solvate water molecules. The latter form a wall of channels with the oxygen atoms of the carboxylate groups of the Pht 2 - 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) 2 Co(Pht)H(Pht)Co(bpy) 2 ]-(HPht)(H 2 Pht).2H 2 O (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 H 2 Pht molecule, and two solvate H 2 O 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 I I complexes, which combine into four [(bpy) 2 Co(Pht)H(Pht)-Co(bpy) 2 ] + units. The main structural unit of the cyclic dinuclear complex [Co(Pht)(bpy)(H 2 O)] 2 .2H 2 O (4) is neutral and cenrosymmetric, with the two Co I I 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)(H 2 O) 3 ].3H 2 O (3) and the polynuclear helical coordination polymer [Co(Pht)(bpy)-(H 2 O)] 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 IDI = 70 cm - 1 , g = 2.55 and J = -0.1 cm - 1 ; for complex 3 IDI = 80 cm - 1 , g = 2.6, and for complex 5 IDI = 65 cm - 1 , g = 2.45. Complex 1 is diamagnetic.
Databáze: OpenAIRE
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