Abstract
The ligand 1-(1-(pyridin-2-yl)ethylidene)carbonohydrazide (H4L1) and 1-(pyridin-2-ylmethylene)carbonohydrazide (H4L2) were prepared by reaction of carbonohydrazide with 2-acetylpyridine or pyridine carbaldehyde respectively in a reflux methanol solution. The complexes are prepared by reaction of the ligand with the appropriate metal salt. These complexes are well characterized by elemental analysis, IR and UV spectroscopies and their structure were determined by single X-ray diffraction technic. In the crystal of the dinuclear complex [Mn2(H4L1)2(H2O)4]·Cl4, 1) each Mn(II) center is seven coordinated by two nitrogen atom and one carbonyl atom of the one ligand and one nitrogen atom and one carbonyl oxygen atom of another ligand molecule. The coordination sphere is completed by two water molecules. Each of the carbonyl oxygen atom acts as bridge between the two Mn(II) centers. In the mononuclear complex [Co(H4L2)(NO3)(H2O)2]·(NO3); 2) the Co(II) center is heptacoordinated. The ligand acts in tridentate fashion through two nitrogen atoms and one carbonyl oxygen atom. Two water molecules lie in the apical positions. One nitrate group acts in bidentate manner while the other nitrate group remains uncoordinated. In both complexes the coordination polyhedral are best described as a pentagonal bipyramid. The molecules are linked together in each case by multiple hydrogen bond interaction resulting in a three-dimensional network. The crystallographic data has been deposited in Cambridge Crystallographic Data Centre [CCDC No. 1944387 (complex 1) and 1944386 (complex 2)].
Highlights
Transition metal coordination compounds with Schiff bases continue to attract the attention of researchers because of the easier synthesis, the stability of the molecular structures and the large diverse properties observed [1]-[11]
We report the isolation and complete characterization of this ligand and its Mn(II) and Co(II) complexes in which the metal centers are heptacoordinated as showed by crystal X-ray diffraction analysis
We describe here one seven coordinated manganese (II) complexes of the tetradentate ligand 1-(1-(pyridin-2-yl)ethylidene)carbonohydrazide and one seven coordinated cobalt(II) of the tridentate 1-(pyridin-2-ylmethylene)carbonohydrazide
Summary
Transition metal coordination compounds with Schiff bases continue to attract the attention of researchers because of the easier synthesis, the stability of the molecular structures and the large diverse properties observed [1]-[11]. Heptacoordinated manganese (II) and cobalt (II) structures have attracted a great deal of interest from chemists in recent years [8] [27] [28] [29] These kind of structures are present in enzymes: catalase [30] [31], ribonucleotide manganese reductase [32] and arginase [33]. By controlling the conditions of the reaction we prepared a ligand from the monocondensation of carbonohydrazide and acetyl pyridine or pyridine carbaldehyde The topologies of these dissymmetric ligands lead it to act in tridentate or tetradentate fashions leading fascinating structures. In this context, we report the isolation and complete characterization of this ligand and its Mn(II) and Co(II) complexes in which the metal centers are heptacoordinated as showed by crystal X-ray diffraction analysis. The structure of the formed crystals has been by single X-ray diffraction analysis and the data have been deposited in CCDC Cambridge crystallographic data centre
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