Synthesis, Spectroscopic and Magnetic Studies on Metal Complexes of 5-Methyl-3-(2-Hydroxyphenyl)Pyrazole

Abstract

A tridentate ONN donor ligand, 5-methyl-3-(2-hydroxyphenyl)pyrazole; H 2 L, was synthesized by reaction of 2-(3-ketobutanoyl)phenol with hydrazine hydrate. The ligand was characterized by IR, 1 H NMR and mass spectra. 1 H NMR spectra indicated the presence of the phenolic OH group and the imine NH group of the heterocyclic moiety. Different types of mononuclear metal complexes of the following formulae [(HL) 2 M] Á xH 2 O (M¼VO, Co, Ni, Cu, Zn and Cd), [(HL) 2 M(H 2 O) 2 ] (M¼Mn and UO 2 ) and [(HL)LFe(H 2 O) 2 ] were obtained. The Fe(III) complex, [(HL)LFe(H 2 O) 2 ] undergoes solvatochromism.Elemental analyses, IR, electronic and ESR spectra as well as thermal, conductivity and magnetic susceptibility measurements were used to elucidate the structures of the newly prepared metal complexes. A squarepyramidal geometry is suggested for the VO(IV) complex, square-planar for the Cu(II), Co(II) and Ni(II) complexes, octahedral for the Fe(III) and Mn(II) complexes and tetrahedral for the Zn(II) and Cd(II) complexes, while the UO 2 (VI) complex is eight-coordinate. Transmetallation of the UO 2 (VI) ion in its mononuclear complex by Fe(III), Ni(II) or Cu(II) ions occurred and mononuclear Fe(III), Ni(II) and Cu(II) complexes were obtained. IR spectra of the products did not have the characteristic UO 2 absorption band and the electronic spectra showed absorption bands similar to those obtained for the corresponding mononuclear complexes. Also, transmetallation of the Ni(II) ion in its mononuclear complex by Fe(III) has occurred. The antifungal activity of the ligand and the mononuclear complexes were investigated.

Synthesis, characterization and antioxidant activity of Schiff base and its metal complexes with Fe(II), Mn(II), Zn(II), and Ru(II) ions: Catalytic activity of ruthenium(II) complex

“…The presence of coordinated water in the complexes was indicated by a broad trough band in the region 3550-3300 cm -1 and two weaker bands in the region 868 and 822 cm -1 due to ν(OH) rocking and wagging mode of vibrations, respectively [31]. The IR spectrum of Ru(II)-arene complex, though not showing the Ru-N vibration which lie below 500 cm −1 , was in accordance with this structure since a red shift was observed for the ligand's CH=N bands associated with metal coordination [32].…”

Statistical modeling-approach for optimization of Cu2+ biosorption by Azotobacter nigricans NEWG-1; characterization and application of immobilized cells for metal removal

“…Copper -oxygen (Cu-O) stretching bands have been notable at 447 cm −1 . The lower frequency regions of IR spectra of all complexes recorded weak bands around 447-558 cm −1 is attributed to Cu-N bonds 63 .…”

New Square-Pyramidal Oxovanadium (IV) Complexes Derived from Polydentate Ligand (L<sup>1</sup>)

“…[33]. The data of IR spectra gathering with electronic spectra suggest a square-pyramidal geometry around the V 4+ ion [34]. But, the value of the magnetic moment of the complex is 2.7 B.M which is higher than the proposed for d 1 -system; recommending an orbital contribution [35].…”

“…But, the value of the magnetic moment of the complex is 2.7 B.M which is higher than the proposed for d 1 -system; recommending an orbital contribution [35]. Figure S23) [33], in a square-pyramidal geometry around the V 4+ ion [34]. Also, the bands at 34,965, 31,847 and 25,641 Figure S24) reveals five bands at 35,971, 33,333, 24,509, 17,361 and 12,987 cm −1 .…”