The complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with ligand (H2L=C13H12N2O5) formed by condensation reaction of isatin and glutamic acid were synthesized. Their physico-chemical properties ...were characterized using elemental analysis, XRF, XRD, FTIR, TG–DSC and TG–FTIR methods and magnetic measurements (Gouy’s and SQUID-VSM methods). The complexes were obtained in crystalline forms (monoclinic or triclinic) with the formulae: M(LH)2·nH2O for Mn(II), Ni(II) and Zn(II) and ML·nH2O for Co(II) and Cu(II), where LH=C13H11N2O5–, L-=C13H10N2O52–, n = 1 for Mn(II), Cu(II) and Zn(II), n = 2 for Co(II) and n = 3 for Ni(II). In air at 293–1173 K they decompose in three steps forming finally the oxides of the appropriate metals. The gaseous decomposition products were identified as: H2O, CO2, CO, hydrocarbons and N2O. The magnetic moment values for complexes (except Zn(II) complex) show their paramagnetic properties with the ferro- and antiferromagnetic interactions between central ions. The compounds of Mn(II) and Co(II) are high spin complexes with weak ligand field. In Co(II) and Cu(II) complexes two carboxylate groups take part in the metal ion coordination while in those of Mn(II), Ni(II) and Zn(II) only one carboxylate anion coordinates to central ion.
Complexes of Ni(II) 2,3-, 3,5- and 2,6-dimethoxybenzoates have been synthesized, theirphysico-chemical properties have been compared and the influence of the position of –OCH3 sub-stituent on their ...properties investigated. The analysed compounds are crystalline, hydrated salts withgreen colour. The carboxylate ions show a bidentate chelating or bridging coordination modes. Thethermal stabilities of Ni(II) dimethoxybenzoates were investigated in air in the range of 293-1173 K.The complexes decompose in three steps, yelding the NiO as the final product of decomposition. Theirsolubilities in water at 293 K are in the order of 10 -2 -10 -4 mol⋅dm -3 . The magnetic susceptibilities forthe analysed dimethoxybenzoates of Ni(II) were measured over the range of 76-303 K and the mag-netic moments were calculated. The results reveal that the complexes are the high-spin ones and theligands form the weak electrostatic field in the octahedral coordination sphere of the central Ni(II) ion.The various position –OCH3 groups in benzene ring cause the different steric, mesomeric and induc-tive effects on the electron density in benzene ring.
The Mn(II) complexes with two commonly used herbicides: 4-chloro-2-methylphenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D) as well as with 4-bromophenoxyacetic acid (4-Br) were ...synthesized and structurally characterized.
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The reaction of manganese(II) chloride with ammonium salt of 4-chloro-2-methylphenoxyacetic acid (MCPA), 2,4-dichlorophenoxyacetic acid (2,4-D) and 4-bromophenoxyacetic acid (4-Br) gave rise to the formation of hydrated complexes with formulas: Mn(MCPA)2·2H2O, Mn(2,4-D)2·2H2O and Mn(4-Br)2·3H2O. The compounds were characterized by elemental and thermal analyses, spectroscopic methods, as well as, by magnetic measurements. The complexes crystallize in monoclinic system. The Mn(II) ion is surrounded by oxygen atoms (from carboxylate groups and water molecules) in the octahedral arrangement. Variable-temperature (1.8–300 K) magnetic susceptibility measurements showed that compounds obey the Curie-Weiss law and have the paramagnetic properties. Being heated up to 1173 K the complexes decompose in three steps - first to anhydrous compounds: Mn(MCPA)2/Mn(2,4-D)2/Mn(4-Br)2 through intermediate products: MnO/Mn2OCl2/Mn2OBr2 to the following oxides: Mn2O3/Mn3O4/Mn3O4. The X-ray single crystal structure analysis was performed for Mn(II) complex with 4-bromophenoxyacetic acid after its recrystallization from N,N-dimethylformamide. The formation of hexanuclear cluster of manganese(II) carboxylate with a hydrophobic exterior was observed.
4-Chlorophenoxyacetates of lanthanides(III) were synthesized as
polycrystalline hydrated solids with the general formulae:
Ln(C8H6ClO3)3?2H2O (Ln = La(III), Pr(III), Sm(III), Eu(III) and Tb(III)),
...Ln(C8H6ClO3)3?H2O (Ln = Dy(III)) and Ln(C8H6ClO3)3?3H2O (Ln = Er(III),
Tm(III), Yb(III) and Lu(III) and characterized by elemental analysis, FTIR
spectroscopy, magnetic and thermogravimetric studies and also by X-ray
diffraction (XRD) measurements. The complexes have colours typical for
lanthanide(III) ions. The carboxylate groups bind as bidentate chelating. On
heating to 1273 K in air the complexes decompose in three steps. At first
they dehydrate in one stage to form anhydrous salts that next decompose to
the oxides of respective metals with the intermediate formation of their
oxychlorides. The gaseous products of compound thermal decomposition in
nitrogen were also determined and the magnetic susceptibilities were
measured over the ranges 76-303K and 1.8-303K, and their magnetic moments
were calculated. The results show that 4-chlorophenoxyacetates of
lanthanides(III) are high-spin complexes with weak ligand field.
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•Three mononuclear complexes with herbicide-2,4-D were structurally investigated.•Metal–ligand interactions were studied by XAS and DFT.•Monodentate coordination by carboxylate ...ligands was found for powder samples.•Dinuclear ‘Chinese lantern’ structure was found for crystallized Ni(II) complex.
The Co(II), Ni(II) and Cu(II) complexes with herbicide 2,4–dichlorophenoxyacetic acid (2,4-D) were synthesized and structurally characterized. The geometry of metal-ligand interaction was refined using XAFS and DFT studies. The Co(2,4-D)2·6H2O and Ni(2,4-D)2·4H2O complexes have octahedral geometry with two carboxylate groups of 2,4-D anions and four water molecules in the coordination sphere. The square planar geometry around metal cations formed by the carboxylate groups from two monodentate ligands and two water molecules, is observed for Cu(2,4-D)2·4H2O complex. In the recrystallized Ni(II) complex dinuclear ‘Chinese lantern’ structures with bridging carboxylate groups of 2,4-D were observed.
The aim of the presented paper is to study an influence of replacement of Fe atoms by Si atoms in quasibinary Sc(Fe
Si
Laves phases on their structural and magnetic properties. Powder X-ray ...diffraction (XRD) and neutron diffraction (ND) measurements carried out at different temperatures from 4.3 K up to about 700 K revealed that samples were single phase with cubic
15 structure for Si concentration
from 0.05 to 0.20 and hexagonal
14 structure for higher concentration. The results of
Fe Mössbauer measurements showed that the Sc(Fe
Si
compounds with
≤ 0.30 are ferrimagnetic at 4.3 K. At temperature 80 K in the samples with
= 0.20 and 0.30, a magnetic cluster spin-glass state has been observed, as ferrimagnetic long-range order disappears. Such picture was supported by the results of ND measurements carried out at 8 K, which confirmed the lack of long-range order for
above 0.10 and an occurrence of hyperfine field distributions in the corresponding Mössbauer spectra. At room temperature, samples with
≥ 0.20 became paramagnetic. A substitution of Si atoms for Fe ones leads to a decreasing of mean values of hyperfine magnetic fields in samples under investigation. From the neutron diffraction pattern analysis of Sc(Fe
Si
Fe magnetic moment was determined as to be equal to 1.5 μ
at 8 K. Combining this result with a value of hyperfine magnetic field on
Fe probes, the hyperfine coupling constant A in Sc(Fe
Cu
phases is estimated at about 11.6 T/μ
at 8 K.
A new dinuclear Cu(II) complex with an auxin-like molecule 2,4-dibromophenoxyacetic acid (1) has been synthesized and characterized as a model compound with an encapsulated metal core for ...considerations on coordination modes of the multidentate phenoxyacetate ligand.
The role of halogen bonding in the crystal packing of 1 is discussed. The energetic features of halogen interactions C–Br···π (d(Br···π) 3.27 Å, −3.5 kcal/mol) and dipole···dipole C–Br⋯C–Br (d(Br⋯C) 3.34 Å, −2.9 kcal/mol) in crystal have been analysed using X-ray crystallography, Hirshfeld surface analysis, DFT calculations (M06-2X-D3/def2-TZVP) and NCIplot computational tool.
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•Halogen bonding was analysed in crystal of dinuclear Cu(II) complex with an auxin-like molecule 2,4-dibromophenoxyacetic acid.•Hirshfeld surface analysis showed a relevant contribution of Br···H contacts and C–Br···π and dipole···dipole interactions.•DFT study showed halogen bond being stronger than antiparallel dipole–dipole C–Br···C–Br interaction (–3.5 vs –2.9 kcal/mol).
The molecular structure of the metal complexes with MCPA herbicide have been determined in their powder form. The cytotoxicity of the parent ligand and its complexes was evaluated against Chinese ...hamster lung fibroblast (V79) and the human immortalized keratinocyte cells (HaCaT).
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The purpose of our research was to obtain and characterize Cu(II), Co(II) and Ni(II) complexes with herbicide 4-chloro-2-methylphenoxyacetic acid (MCPA). The structural characterization of compounds in their powder form was based on various laboratory as well as synchrotron X-ray spectroscopic methods, magnetic measurements and atomistic calculations. The anhydrous Cu(MCPA)2n complex exhibits a distorted square-planar geometry. Co(MCPA)2(H2O)4·H2O and Ni(MCPA)2(H2O)4·H2O complexes have octahedral molecular geometry with two MCPA anions acting as monodentate ligands. The X-ray crystal structure analysis performed for Cu(II) complex after its recrystallization from N,N-dimethylformamide solution showed the formation of dinuclear complex with solvent molecules included in the coordination sphere of Cu(II).
MCPA herbicide and its Cu(II), Co(II) and Ni(II) complexes showed the low cytotoxicity potential against HaCaT and V79 cells with IC50 in the range from 65 to >100 µM.
This paper presents the interpretations of data obtained from the investigations of 2,4-dichlorophenoxyacetates of selected lanthanide(III) ions. The compounds of 2,4-dichlorophenoxyacetic acid ion ...with La(III), Pr(III)-Lu(III) with the formula Ln(C.sub.8H.sub.5O.sub.3Cl.sub.2).sub.3·nH.sub.2O, where Ln(III) = lanthanides, n = 2, 4 or 5 depending on Ln(III) ions, were synthesized and characterized by elemental analysis, FTIR spectroscopy, magnetic and thermogravimetric studies and also by X-ray powder diffraction (XRD) measurements. The compounds crystallize in monoclinic or triclinic systems. The carboxylate groups act as bidentate chelating agents. On heating in air up to 1173 K, the analysed compounds are decomposed in three steps: they are dehydrated to anhydrous salts which next are decomposed to the oxides of respective metals with intermediate formation of the oxychlorides. The enthalpy values of the dehydration process changed from 44.00 to 91.34 kJ mol.sup.-1. The magnetic moments of compounds were determined in the ranges of 76-303 K and for some of them at 4.2-303 K.
This paper presents the interpretations of data obtained from the investigations of 2,4-dichlorophenoxyacetates of selected lanthanide(III) ions. The compounds of 2,4-dichlorophenoxyacetic acid ion ...with La(III), Pr(III)–Lu(III) with the formula Ln(C
8
H
5
O
3
Cl
2
)
3
·
n
H
2
O, where Ln(III) = lanthanides,
n
= 2, 4 or 5 depending on Ln(III) ions, were synthesized and characterized by elemental analysis, FTIR spectroscopy, magnetic and thermogravimetric studies and also by X-ray powder diffraction (XRD) measurements. The compounds crystallize in monoclinic or triclinic systems. The carboxylate groups act as bidentate chelating agents. On heating in air up to 1173 K, the analysed compounds are decomposed in three steps: they are dehydrated to anhydrous salts which next are decomposed to the oxides of respective metals with intermediate formation of the oxychlorides. The enthalpy values of the dehydration process changed from 44.00 to 91.34 kJ mol
−1
. The magnetic moments of compounds were determined in the ranges of 76–303 K and for some of them at 4.2–303 K.
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