Search results for "schiff base"
showing 10 items of 180 documents
Synthesis and characterization of a new family of bi-, tri-, tetra-, and pentanuclear ferric complexes.
2004
Nine members of a new family of polynuclear ferric complexes have been synthesized and characterized. The reaction of Fe(O(2)CMe)(2) with polydentate Schiff base proligands (H(2)L) derived from salicylidene-2-ethanolamine, followed in some cases by reaction with carboxylic acids, has afforded new complexes of general formulas [Fe(2)(pic)(2)(L)(2)] (where pic(-) is the anion of 2-picolinic acid), [Fe(3)(O(2)CMe)(3)(L)(3)], [Fe(4)(OR)(2)(O(2)CMe)(2)(L)(4)], and [Fe(5)O(OH)(O(2)CR)(4)(L)(4)]. The tri-, tetra-, and pentanuclear complexes all possess unusual structures and novel core topologies. Mössbauer spectroscopy confirms the presence of high-spin ferric centers in the tri- and pentanuclear…
Ferromagnetic exchange coupling in a new bis(μ-chloro)-bridged copper(II) Schiff base complex: Synthesis, structure, magnetic properties and catalyti…
2009
Abstract A new (μ-chloro)-bridged complex [Cu(HL)Cl]2 · H2O (1) with the Schiff base ligand H2L, [2-((E)-(2-hydroxyethylimino)methyl)-4-bromophenol], has been synthesized and characterized by elemental analysis, IR, UV–Vis and EPR spectroscopic studies. X-ray diffraction studies show that 1 is a binuclear CuII complex with a pair of chlorine atoms bridging the copper atoms in a central Cu2Cl2 core. Each copper atom in 1 adopts a distorted square-pyramidal geometry with the imine nitrogen atom, alkoxy and phenoxy oxygen atoms from the Schiff base ligand and a bridging chlorine atom constructing the basal plane, while the apical position of the pyramid is occupied by the other bridging chlori…
Ethylene homo- and copolymerization catalyzed by vanadium, zirconium, and titanium complexes having potentially tridentate Schiff base ligands
2021
Abstract New potentially tridentate Schiff base ligands, 2-[({4-[(3-N,N-dimethylamino)propyl] phenyl}imino)methyl]-4,6-di-tert-butylphenol (L1H) and 2-[{2-(N-phenyl-N-methylaminomethyl)-phenylimino}-methyl]-4,6-di-tert-butylophenol (L2H) were prepared and after deprotonation they were reacted with VOCl3 or MCl4 (where M = Zr or Ti) to produce corresponding complexes (L1-V, L2-V, L1-Zr, L2-Ti) with good yields. All new compounds were characterized by the 1H and 13C NMR as well as FTIR spectroscopic methods. Upon activation with Et2AlCl or EtAlCl2, both the vanadium complexes exhibited exceptionally high catalytic activities in the ethylene polymerization (up to 69,000 kg/(molV⋅h) for L1-V an…
Syntheses, structures, electrochemical measurements and magnetic properties of two iron(III) complexes derived from N,N′-o-phenylenebis(3-ethoxysalic…
2011
Abstract The work in this paper presents syntheses, characterizations, crystal structures, electrochemical measurements and magnetic properties of two iron(III) compounds [FeIIIL(H2O)(MeOH)](ClO4) (1) and [FeIIIL(H2O)2](NO3)·H2O (2) derived from the Schiff base compartmental ligand N,N′-o-phenylenebis(3-ethoxysalicylaldimine) (H2L). The two compounds are characterized by elemental analyses, IR, electrospray ionization mass (ESI-MS positive), UV–Vis spectra and conductance values. The structures of 1 and 2 show that these are mononuclear compounds having the metal ion in the N2O2 compartment. Two mononuclear moieties in both the compounds are self-assembled due to bifurcated hydrogen bonds i…
One dimensional Mn(III) Schiff-base complex organization through very strong symmetrical H-bond interaction
2016
Abstract We are reporting the structural and magnetic characterization of a Mn(III) mononuclear complex based on a Schiff-base ligand with carboxylate pendant arm. Very strong symmetric H-interaction drives a one dimensional organization of this complex, densely packed through C–H⋯π further interactions. Low temperature magnetic behaviour appears governed by local ion zero field splitting obscuring any possible weak exchange interaction through the symmetric H-bond pathway.
2-Amino-2-methyl-1,3-propanediol (ampdH2) as ligand backbone for the synthesis of cobalt complexes: Mononuclear Co(II), binuclear Co(II,III) and hexa…
2013
Abstract Three cobalt complexes have been synthesized using 2-amino-2-methyl-1,3-propanediol (ampdH2) and its Schiff base derivative ligands and structurally characterized. The three complexes 1, 2 and 3 are very different and consist of mononuclear Co(II), mixed-valence binuclear Co(II,III) and mixed-valence hexanuclear Co(II,III) complexes respectively. The properties of the coordinated donor atoms of the ligand play the predominant role in stabilizing the oxidation states of the cobalt centers. The presence of intermolecular hydrogen bonds in 1 via non-coordinating perchlorate ions lead to the formation of a 1D-Chain network while a sheet-like 2D network was observed in 3.
Mononuclear Fe(III) and tetranuclear [Fe(III)Gd(III)]2 complexes with a Schiff-base ligand derived from the o-vanillin: Synthesis, crystal structures…
2011
The mononuclear high-spin iron(III) complexes [Fe(3-MeOsalpn)Cl(H 2 O)] ( 1 ) and [Fe(3-MeOsalpn)(NCS)(H 2 O)]·0.5CH 3 CN ( 2 ) and the tetranuclear oxo-bridged compound [{Fe(3-MeOsalpn)Gd(NO 3 ) 3 } 2 (μ-O)]·CH 3 CN ( 3 ) [3-MeOsalpn 2− = N , N ′-propylenebis(3-methoxysalicylideneiminate)] have been prepared and magneto-structurally characterised. The iron(III) ion in 1 and 2 is six-coordinated in a somewhat distorted octahedral surrounding with the two phenolate-oxygens and two imine-nitrogens from the Schiff-base building the equatorial plane and a water ( 1 and 2 ) and a chloro ( 1 )/thiocyanate-nitrogen ( 2 ) in the axial positions. The neutral mononuclear units of 1 and 2 are assemb…
Copper(II) complexes with tridentate N2O donor Schiff base isomers: Modulation of molecular and crystalline architectures through supramolecular inte…
2013
Abstract Four copper(II) complexes, [Cu(L1)(μ-Cl)]n (1), [Cu2(L2)2(μ-Cl)2] (2), [Cu(L1)(μ1,5-NCNCN)]n (3) and [Cu(L2)(μ1,5-NCNCN)]n (4), where HL1 = 1-[(2-dimethylamino-ethylimino)-methyl]-naphthalen-2-ol and HL2 = 1-[(2-ethylamino-ethylimino)-methyl]-naphthalen-2-ol, acting as tridentate N2O donor ligands, have been prepared and characterized by elemental analysis, IR and UV–Vis spectroscopy and single crystal X-ray diffraction studies. Complexes 1, 3 and 4 show polymeric chain structures, whereas 2 has a double chloride bridged dimeric structure. The existence of C–H⋯π interactions between the dimeric units of 2 gives rise to a 2D supramolecular network. Complex 3 shows a zipper structure…
Homo and heterometallic rhomb-like Ni4 and Mn2Ni2 complexes
2014
Abstract Two new polynuclear complexes with hydroxyl-rich Schiff base ligand 3-[(2-Hydroxy-benzylidene)-amino]-propane-1,2-diol (H3L), namely [NiII2(HL)(H2L)(SCN)]2·DMF (1) and [MnIII2NiII2(HL)2(L)2] (2) have been synthesized and characterized by single crystal X-ray diffraction, elemental analyses, FTIR, UV–Vis spectroscopy and variable temperature magnetic susceptibility measurements. The X-ray refinements reveal that both compounds present defective rhomb-like dicubane central cores (Ni4 in 1 and Mn2Ni2 in 2). Magnetic susceptibility measurements indicate the presence of overall antiferromagnetic exchange interactions in 1 along the side connected by a N and O atoms (J1 = −43.6 cm−1) and…
Solution chemistry of N,N'-ethylenebis(salicylideneimine) and its copper(II), nickel(II) and iron(III) complexes
1991
Abstract Potentiometric determination of protonation-deprotonation equilibria of the N,N'-ethylenebis(salicylideneimine) (H2sal2en), the related N-(2-aminoethyl)salicylideneimine, (Hsalen), and their organic fragments, salicylaldehyde (Hsal) and ethylenediamine (en), has been used to study the equilibria involved in the formation of Schiff bases from Hsal, sal− and en and in their complex formation with copper(II), nickel(II) and iron(III) ions in dimethyl sulfoxide (dmso)-water (80:20 wt./wt.) mixture (25 °C and 0.1 mol dm−3 KClO4 ionic strength): en+Hsal⇔Hsalen; en+2Hsal⇔H2sal2en; en+ sal−⇔salen−; en+2sal−⇔sal2en2−; sal−+en+MN+⇔[M(salen)](n−1)+; 2sal−+en+Mn+⇔ [M(sal2en)](n−2)+. In these t…