Crystal structure of nonadentate tricompartmental ligand derived from pyridine-2,6-dicarboxylic acid: Spectroscopic, electrochemical and thermal investigations of its transition metal(II) complexes

Abstract

a b s t r a c tThe coordinating behavior of a new dihydrazone ligand, 2,6-bis [(3-methoxysalicylidene) hydrazinocarbonyl]pyridine towards manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) and cadmium(II) has been described. The metal complexes were characterized by magnetic moments, conductivity measurements, spectral (IR, NMR, UV-Vis, FAB-Mass and EPR) and thermal studies. The ligand crystallizes in triclinic system, space group P-1, with˛= 98.491(10)• ,ˇ= 110.820(10)• and = 92.228(10)• . The cell dimensions are a = 10.196(7)Å, b = 10.814(7)Å, c = 10.017(7)Å, Z = 2 and V = 1117.4(12). IR spectral studies reveal the nonadentate behavior of the ligand. All the complexes are neutral in nature and possess six-coordinate geometry around each metal center. The X-band EPR spectra of copper(II) complex at both room temperature and liquid nitrogen temperature showed unresolved broad signals with g iso = 2.106. Cyclic voltametric studies of copper(II) complex at different scan rates reveal that all the reaction occurring are irreversible.

Vibrational and conformational analysis on-N1-N2-bis((pyridine-4-yl)methylene) benzene-1,2-diamine

“…Ground state energies, zero point corrected energies (Eelect.+ZPE), relative energies and dipole moments of conformer s were presente d in Table S1 (Supporting informat ion). The conformer one is the most stable one and the theoretical geometry of the title compound fairly well reproduce the experime ntal one [24,25]. The results and discussion of this paper is based on conformer one.…”

“…The exact crystal structure of the title compound is not yet discovered so that the optimized structure can only be compared with other similar system, e.g. 2, 6-bis [3-metho xysalicylidene)hydrazinocarbony l] pyridine [25] and 5-(phenylazo)-N-(2-amino pyridine) salicylidene [24]. It is evident from Table S2 , the optimized bond lengths and bond angles were (31) (continued on next page ) slightly longer than the literature values because the molecular states were different during the experimental and theoretical process.…”

“…The CACAC out-of-plan e deformation s (benzene) are found at 712, 564 cm À1 FT-IR bands and the harmonic bands at 735, 716, 560 cm À1 (mode nos: 33,31,25). Similarly the CACAC in-plane-bendi ng vibrations (pyridine) are attributed to the harmonic bands in the range 657-437 cm À1 (mode nos: 30,29,21,19) and the FT-IR bands at 670, 499, 426 cm À1 .…”

6,6′-Dimethoxy-2,2′-{[(E,E)-hydrazine-1,2-diylidene]bis(methanylylidene)}diphenol methanol disolvate

“…The synthesis of the title compound was originally reported by Lin et al (2009); however, in this study, it was obtained from (2Z,6Z,N 0 2E,N 0 6E)-N 0 2,N 0 6-bis(2-hydroxy-3-methoxybenzylidene)pyridine-2,6-bis(carbohydrazonic) acid (Vadavi et al 2011). The title compound has been used in the synthesis of first-row transition metal complexes (Zou et al 2011) and in the synthesis of lanthanide complexes (Davidson et al 2006).…”

“…DyCl 3 .H 2 O (0.06 g; 0.2 mmol) was dissolved in methanol (20 mL). (2Z,6Z,N′2E,N′6E)-N′2,N′6-bis(2-hydroxy-3-methoxybenzylidene)pyridine-2,6-bis(carbohydrazonic) acid (Vadavi et al 2011) (0.05 g; 0.1 mmol) was added and the solution was refluxed for 3 h. Upon cooling, the resulting solution was gravity filtered and left for slow evaporation at room temperature to yield yellow-orange crystals of the title compound.…”