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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
Author(s) -
Baca Svetlana G.,
Filippova Irina G.,
Ambrus Christina,
Gdaniec Maria,
Simonov Yurii A.,
Gerbeleu Nicolae,
Gherco Olesea A.,
Decurtins Silvio
Publication year - 2005
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200500008
Subject(s) - chemistry , cobalt , carboxylate , molecule , crystallography , phthalic acid , crystal structure , bipyridine , stereochemistry , supramolecular chemistry , inorganic chemistry , organic chemistry
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) 2 Co(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 II 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 II 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 | 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, 69451 Weinheim, Germany, 2005)