Synthesis, Spectroscopic Studies and X-Ray Diffraction of Heptacoordinated Mn(II) and Co(II) Complexes with Ligands Derived from Carbonohydrazide

Abstract

The ligand 1-(1-(pyridin-2-yl)ethylidene)carbonohydrazide (H 4 L 1) and 1-(pyridin-2-ylmethylene)carbonohydrazide (H 4 L 2) 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 [Mn 2 (H 4 L 1) 2 (H 2 O) 4 ]•Cl 4 , 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(H 4 L 2)(NO 3)(H 2 O) 2 ]•(NO 3); 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

Synthesis of mono and bis-substituted asymmetrical compounds, (1-(pyridin-2-yl)ethylidene)carbonohydrazide and 1-(2'-hydroxybenzylidene)-5-(1'-pyridylethylidene)carbonohydrazone: Structural characterization and antioxidant activity study

“…Both infrared spectra of compounds 1 and 2 exhibit broad bands in the range 3310-3185 cm -1 which are attributed to N-H stretching [28]. The vibration of the imine functions appears in the range 1634-1619 cm -1 while the band due to C=O group is in the range 1694-1671 cm -1 as reported for similar Schiff base [29]. Bands due to the aromatic ring are pointed in the region 1584-1462 cm -1 .…”

Crystal structures of bis-{N-[1-(pyridin-2-yl-κN)ethylidene]nicotine hydrazide-κ2N’,O}cobalt(II)bis(perchlorate) dihydrate and bis-{N'-[1-(pyridin-2-yl-κN)ethylidene]nicotinohydrazide-κ2N',O}copper(II) perchlorate

“…1612 cm -1 for complex 2. The shift of the ν(C=N) band from 1605 cm -1 in the ligand spectrum to 1583 cm -1 for complex 1 and 1588 cm -1 for complex 2 is indicative of the involvement of the azomethine atoms in coordination to the Co(II) and Cu(II), respectively [35]. The broad band centered in the range 3090-3110 cm -1 is probably due to the stretching of H-N [36].…”

Synthesis, Spectroscopic, Characterization and X-ray Structures of Lanthanide(III) Complexes Derived from 1,5-bis(phenyl(pyridin-2-yl)methylene)carbonohydrazide

“…In the infrared spectrum of the ligand a medium sharp band is observed around 3346 cm -1 which is attributed to the vibration of the N-H bond [42]. The bands at 3160 cm -1 and 3057 cm -1 are attributed to the valence vibrations of C Ar -H bonds [42].…”

“…The bands at 3160 cm -1 and 3057 cm -1 are attributed to the valence vibrations of C Ar -H bonds [42]. The vibration bands ν C=O and ν C=N were respectively pointed at 1698 cm -1 and 1630 cm -1 [42]. Bands dues to ν C=N of the pyridine ring and ν C=C of the phenyl ring are pointed in the range 1570 cm -1 -1420 cm -1 [46].…”

“…In addition to their physical properties [28][29][30][31][32], the antimicrobial, antitumor or antioxidant properties of lanthanide complexes have been explored in recent decades [33][34][35][36][37][38][39][40][41]. Our research group explored the chemistry of lanthanide compounds containing carbonohydrazide ligands [42]. Our synthetic approach consists in preparing the symmetrical ligand 1,5-bis (phenyl (pyridin-2-yl) methylene) carbonohydrazide (H 2 L) which possesses seven potential coordinating sites.…”