Search results for "Magnetism"

1,2,4-Triazole Schiff base directed synthesis of polynuclear iron complexes: Investigating the magnetic properties going from a dimer to a 1D chain t…

2018

Abstract Based on two functionalized Schiff base ligands 4-(1H-imidazol-5-ylmethylene-amino)-4H-1,2,4-triazole (imztrz) and 4-(p-tolylidene-amino)-4H-1,2,4-triazole (toltrz), a series of three triazole based polynuclear Fe complexes has been prepared. Compounds {[FeII(toltrz)2(C2O4)]·10H2O}n (1) and {[FeII(5-imztrz)(C2O4)]·2H2O}n (2) are oxalate bridged FeII complexes with 1 showing a linear 1D chain structure and 2 exhibiting a zigzag chain based 3D interpenetrating framework. Both structures show rather big voids in the 3D architecture (∼15% of the crystal volume). Compound (5-imztrzH)2[FeIII2(cit4−)2(H2O)2]·6H2O (3) is a binuclear FeIII complex bridging by two citrate ligands to form a f…

Synthesis, structure and magnetic characterization of a dinuclear and two mononuclear iron(III) complexes with N,O-donor Schiff base ligands

2018

Abstract One centrosymmetric dinuclear and two mononuclear iron(III) Schiff base complexes, [(µ-OMe)2Fe2(L1)2(N3)2] (1) {HL1 = 2-((2-(dimethylamino)ethylimino)methyl)-6-ethoxyphenol}, [FeL2(OH2)(N3)]·CH3OH (2) {H2L2 = N,N′-bis(3-ethoxysalicylidene)propane-1,3-diamine} and [FeL3(OH2)(NCS)]·2H2O (3) {H2L3 = N,N′-bis(3-methoxysalicylidene)propane-1,3-diamine}, have been synthesized and characterized by elemental analysis and spectral studies. X-ray diffraction analysis was used to determine the structures of all three complexes. Variable temperature (2–300 K) magnetic susceptibility (χ) data of complex 1 show that both iron(III) centres in the complex are in a high spin configuration (S = 5/2)…

Rare trinuclear NiII2MII complexes (MII = Mn, Fe and Co) with a reduced Schiff base ligand: Synthesis, structures and magnetic properties

2018

Abstract Three new trinuclear hetero-metallic NiII2MII complexes with MII = Mn, Fe and Co have been synthesized using a [NiLR] “metalloligand”, where H2LR = N,N′-bis(2-hydroxybenzyl)-1,3-propanediamine. All complexes have been characterized by elemental analysis, spectroscopic methods, single crystal XRD and magnetic and electrochemical studies. In the three complexes, in addition to the double phenoxido bridges, the two terminal NiII atoms are linked to the central MII [M = Mn(1), Fe(2) and Co(3)] ion by means of a bridging carboxylato co-anion, giving rise to a linear NiII-MII-NiII structure. Variable temperature magnetic susceptibility measurements show the presence of weak ferromagnetic…

Fe II Complexes with Triple N 1, N 2‐Triazole Bridge Schiff Base Ligand: Antiferromagnetic Dimer vs. Spin Conversion Trimer

2018

A new linear double phenoxide-bridged trinuclear Cu(II) Schiff base complex: Synthesis, crystallographic elucidation, magneto-structural correlation …

2014

Abstract The tetradentate (ONNO) donor Schiff base ligand LH2, derived from the condensation of salicylaldehyde and 1,3-diaminopropane, has been synthesized and reacted with CuBr2 to yield a trinuclear complex with the molecular formula [Cu3L2Br2]. Single crystal X-ray diffraction study reveals that the two terminal copper atoms adopt a square pyramidal geometry, whereas the central copper atom, situated at the inversion centre, is surrounded by four phenoxide oxygen atoms in a square planar fashion. Variable temperature magnetic susceptibility measurement study shows strong antiferromagnetic intra-trimer interactions between the copper centers with a J value of −302 cm−1. EPR study of the …

Quantitative estimation of the antiferromagnetic interaction between Cu(II) and Sm(III) in two dimensional heterometallic coordination polymer with i…

2013

Abstract The syntheses, structure and magnetic property of a novel two dimensional 3d–4f coordination polymer 2∞[CuSmL(NO3)2(IN)], 1 (L2−  = N, N′- propylenedi (3-ehoxysalicylideneiminato), the dianion of the Schiff base obtained from the 2:1 condensation of 3-ethoxysalicylaldehyde with 1,3-propanediamine, IN− = the isonicotinate ion) has been reported. The heterobinuclear units are connected through exo-bidentate ligands IN−, leading to an extended 2D structure. A fit of the magnetic susceptibility data yields gCu = 2.109, gSm = 0.476, JCuSm = − 0.893 cm− 1, θ = − 3.37 K, and TIP = 0.001257 emu K mol− 1 with a good discrepancy factor of Rχ = 4.4 × 10− 5. This is the first quantitative esti…

Coordination versatility of 1,5-bis(salicylidene)carbohydrazide in Ni(II) complexes

2014

Abstract Versatile coordination behavior of a polydentate Schiff base ligand 1,5-bis(salicylidene)carbohydrazide (H3bsc) has been explored in Ni(II) complexes. [Ni(H3bsc)2](ClO4)2 (1)·H2O·3CH3CN is a bis chelate mononuclear complex of H3bsc in keto form, and [Ni4(H0.5bsc)2(O2CCMe3)3(CH3OH)4](2)·2H2O·2CH3OH is a tetranuclear complex of H3bsc with an unusual coordination. In 2, one phenolate group of the ligand coordinates in a monodentate way and the other coordinates in a μ2-bridging mode to the Ni(II) center. This unusual coordination mode of the ligand stabilizes the Ni(II) complex in a tetranuclear form where the carbonyl oxygen of the ligand exists in between keto and enol form of bond …

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…

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…

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…