We report the synthesis of Co(II), Ni(II) and Cu(II) complexes with p-bromophenoxyacetic acid (p-BPAA). For powder form of compounds, we find that mononuclear complexes are formed with two ...carboxylate ligands coordinating to the metal cation. In single crystal structure of Cu(II) complex, the bridging carboxylate groups and DMF molecules stabilize dinuclear Cu2O10 center.
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We report the synthesis of new Co(II), Ni(II) and Cu(II) complexes with 4-bromophenoxyacetic acid. We characterize these compounds structurally using various laboratory (XRF, IR, UV–vis) and synchrotron (EXAFS, XANES) spectroscopic methods, magnetic measurements and DFT calculations. We found that in the powder form of complexes Co(II) and Ni(II) cations are coordinated by two monodentate carboxylate ligands and the first coordination sphere is completed by water molecules that form an octahedron. The coordination polyhedron of Cu(II) exhibits a distorted tetragonal–pyramidal geometry with two ligands coordinating in bidentate and monodentate fashion via carboxylate O atoms and two water molecules.
The X-ray single crystal structure analysis performed for Cu(II) complex after its recrystallization from N,N-dimethylformamide (DMF) solution revealed the formation of dinuclear complex. In crystals, the carboxylate O atoms occupy the bases of two tetragonal pyramids formed around two Cu(II) ions with the DMF molecules in the apical positions.
Four heteroleptic complexes of nickel(ii), cobalt(ii) and zinc(ii), containing a monodentate silanethiolate ligand derived from tris(2,6-diisopropylphenoxy)silanethiol (TDST), were prepared and ...characterized. Nickel(ii) and cobalt(ii) complexes of the formula M(NH3)2(TDST)2 (M = Ni(ii) complex , M = Co(ii) complex ) were obtained from the respective chlorides. Zinc complexes of the general formula Zn(acac)(TDST)(L), where L = EtOH (complex ) or H2O (complex ), were obtained from zinc acetylacetonate. A single-crystal X-ray structural analysis revealed that all crystalline products are solvent adducts. The geometries of ligands in the complexes are typical: distorted tetrahedral in zinc and cobalt(ii) complexes and square planar in nickel(ii) compounds. Magnetic studies performed for Ni(ii) and Co(ii) compounds confirmed the diamagnetic character of the first complex and high-spin paramagnetic configuration of the latter. Nickel(ii) and cobalt(ii) complexes were additionally characterized by UV-Vis and IR spectroscopy. IR bands for ligands in the complexes were assigned with the help of the DFT vibrational frequency calculations.
The aim of this work was to study the spectroscopic and magnetic properties of copper(II)
o
-,
m
-,
p
-aminobenzoates,
o
-,
m
-,
p
-methoxybenzoates and
o
-,
m
- and
p
-nitrobenzoates. The complexes ...were synthesized and their compositions were evaluated by elementary analysis. The infrared and Raman spectra for Cu(II) aminobenzoates, methoxybenzoates and nitrobenzoates were recorded and assigned. The obtained data were compared with those previously published for aminobenzoic, methoxybenzoic and nitrobenzoic acids and their sodium salts. The structures of Cu(II)
o
-,
m
-,
p
-aminobenzoates,
o
-,
m
-,
p
-methoxybenzoates and
o
-,
m
- and
p
-nitrobenzoates as well as the change in the electronic charges distribution caused by Cu(II) complex formation were discussed.
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•New complexes of the HL acid ligand with transition metal were synthesized.•The crystal structure was determined for Cu(II) complex.•Elemental analysis, X ray diffraction, FTIR, ...TG-DSC, Gouy and SQUID methods.
The new complexes of 4-oxo-4-{3-(trifluoromethyl)phenylamino}but-2-enoic acid, HL anion with Mn(II), Co(II), Ni(II), Cu(II) and Pr(III), Nd(III), Sm(III), Gd(III), Dy(III), Ho(III), Er(III), Y(III) were synthesized and some of their physico-chemical properties investigated. The complexes form hydrates with two or three molecules of water. The carboxylate groups act as a bidentate bridging or chelating ligand. The compounds of Pr(III), Nd(III), Sm(III), Gd(III), Dy(III), Ho(III), Er(III) and Y(III) are amorphous solids while those of Cu(II), Co(II), Ni(II) and Mn(II) crystalline ones that crystallize in monoclinic system. Complex of Cu(II) is the centrosymmetric dinuclear compound. Around both Cu(II) cations the tetragonal pyramide is formed. Being heated in air at 293–1173K the complexes are decomposed in three steps. The oxides of appropriate metals are the final products of complex decomposition. All analysed compounds obey Curie–Weiss law. They show the paramagnetic properties with the ferromagnetic interactions between molecular centres.
In this study, 4-methoxycinnamates of Mn(II), Co(II), Ni(II), Cu(II), Cd(II), Nd(III) and Gd(III) were synthesised. From the infrared (IR) spectra analysis of complexes, sodium salt and according to ...the spectroscopic criteria the carboxylate groups seem to be bidentate chelating. The complexes of 4-methoxycinnamates lose the water molecules in one or two steps. The final products of their decomposition are oxides of the respective metals. The enthalpy values of dehydration process were determined. The FTIR spectra of the gas phase products indicate that the decomposition of the complexes is connected mainly with the release of molecules of water (H
2
O), carbon dioxide (CO
2
), carbon monoxide (CO), methane (CH
4
) and other hydrocarbons. The analysed compounds follow the Curie–Weiss law. The magnetic moment values experimentally determined change as follows: from 5.90
μ
B
to 6.27
μ
B
for Mn(II) complex, from 4.57
μ
B
to 4.99
μ
B
for Co(II) complex, from 3.68
μ
B
to 3.30
μ
B
for Ni(II) complex, from 1.87
μ
B
to 1.96
μ
B
for Cu(II) complex, from 3.06
μ
B
to 3.51
μ
B
for Nd(III) complex, and from 6.91
μ
B
to 6.90
μ
B
for Gd(III) complex.
The complexes of 2-methoxyhenoxyacetates of Mn(II), Co(II), Ni(II) and Cu(II)with the general formula: M(C9H9O4)3·4H2O, where M(II) = Mn, Co, Ni and Cu have been synthesized and characterized by ...elemental analysis, IR spectroscopy, magnetic and thermogravimetric studies and also X-ray diffraction measurements. The complexes have colours typical for M(II) ions (Mn(II) - a pale pink, Co(II) - pink, Ni(II) - green, and Cu(II) – blue). The carboxylate group binds as monodentate and bidentate ligands. On heating to 1273K in air the complexes decompose in the same way. At first, they dehydrate in one step to anhydrous salts, that next decompose to the oxides of respective metals with the intermediate formation of the oxycarbonates. Their solubility in water at 293K is of the order of 10-5 mol·dm-3. The magnetic moments of analysed complexes were determined in the range of 76-303K. The results reveal them to be high-spin complexes of weak ligand fields.
Lanthanide(III) 4-nitrocinnamates were synthesized as polycrystalline hydrated solids with the general formulae: Ln(C9H6NO4)3OH2O (where Ln = lanthanons (without Ce(III)), n=1 for La, Pr-Tb and n=2 ...for Dy-Lu). The complexes were characterized by elemental analysis, FTIR spectroscopy, magnetic and thermogravimetric studies and also by X-ray diffraction (XRD) measurements. The carboxylate groups bind as bidentate chelating. On heating to 1173 K in air all compounds at first dehydrate in one stage to form anhydrous salts, that next with rising temperature are being directly decomposed (complexes of Pr(III) and Eu(III)) or with the intermediate formation of oxycarbonates (the rest of analysed compounds) to the oxides of respective metals. The gaseous products of compound thermal decomposition in nitrogen were also determined. The magnetic susceptibilities were measured over the ranges 76-303 K and 1.8-303 K, and their magnetic moments were calculated. The results show that 4-nitrocinnamates of lanthanides(III) are high-spin complexes with weak ligand field.
Abstact
5-Chloro-2-nitrobenzoates of Co(II), Ni(II) and Cu(II) having formulae Co(C
7
H
3
O
4
NCl)
2
·3H
2
O, Ni(C
7
H
3
O
4
NCl)
2
·3H
2
O and Cu(C
7
H
3
O
4
NCl)
2
·2H
2
O, were obtained as ...polycrystalline compounds. From the IR spectra analysis of complexes, sodium salt and according to the spectroscopic criteria the carboxylate ions seem bidentate groups. The complexes of Co(II) and Cu(II) lose the water of crystallization in one step at 363–523 K. The Ni(II) complex loses it in two stages in the ranges of 323–378 and 378–523 K, respectively. The compounds follow the Curie–Weiss law. The magnetic moment values experimentally determined change from 4.53 to 4.55 μ
B
for Co(II) complex, from 2.34 to 2.97 μ
B
for Ni(II) 5-chloro-2-nitrobenzoate and from 1.80 to 1.90 μ
B
for Cu(II) complex.
The complexes of 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III) have been synthesized as polycrystalline hydrated solids, and characterized by elemental analysis, spectroscopy, magnetic ...studies and also by X-ray diffraction and thermogravimetric measurements. The analysed complexes have the following colours: violet for Nd(III), white for Gd(III) and cream for Ho(III) compounds. The carboxylate groups bind as bidentate chelating (Ho) or bridging ligands (Nd, Gd). On heating to 1173K in air the complexes decompose in several steps. At first, they dehydrate in one step to form anhydrous salts, that next decompose to the oxides of respective metals. The gaseous products of their thermal decomposition in nitrogen were also determined and the magnetic susceptibilites were measured over the temperature range of 76-303K and the magnetic moments were calculated. The results show that 4-chlorophenoxyacetates of Nd(III), Gd(III) and Ho(III) are high-spin complexes with weak ligand fields. The solubility value in water at 293K for analysed 4-chlorophenoxyacetates is in the order of 10-4mol/dm3.
The physico-chemical properties of the new 3d-4f heteronuclear complexes with general formula LnCu3(C11H8N2O4Br)3·13H2O (where Ln = Pr, Eu, Gd, Tb, Er, Yb and H3(C11H8N2O4Br) – ...5-bromosalicylideneglycylglycine) were studied. The compounds were characterized by elemental, spectral and thermal analyses and magnetic measurements. The formation of Schiff base is evidenced by a strong band at ca. 1646–1650 cm–1 attributable to C=N stretching mode. The presence of water molecules is confirmed by broad absorptions with maximum at 3360 – 3368 cm-1. The Cu(II)–Ln(III) complexes are stable up to ca. 318 K. During dehydration process the water molecules are lost probably in two stages. The magnetic susceptibility data for these complexes change with temperature according to the Curie-Weiss law.
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