Physico-chemical properties of 3,4-dimethoxybenzoates of Co(II), Cu(II), La(III) and Nd(III)were studied. The complexes were obtained as hydrated or anhydrous polycrystalline solids with a ...metalion–ligand mole ratio of 1 : 2 for divalent ions and of 1 : 3 in the case of trivalent cations. Their coloursdepend on the kind of central ion: pink for Co(II) complex, blue for Cu(II), white for La(III) and violetfor Nd(III) complexes. The carboxylate groups in these compounds are monodentate, bidentate bridgingor chelating and tridentate ligands. Their thermal decomposition was studied in the range of 293–1173 K.Hydrated complexes lose crystallization water molecules in one step and form anhydrous compounds,that next decompose to the oxides of respective metals. 3,4 – Dimethoxybenzoates of Co(II) is directlydecomposed to the appropriate oxide and that of Nd(III) is also ultimately decomposed to its oxide butwith the intemediate formation of Nd 2 O 2 CO 3. . The magnetic moment values of 3,4–dimethoxybenzoatesdetermined in the range of 76–303 K change from 4.22 μ B to 4.61 μ B for Co(II) complex , from 0.49 μ Bto 1.17 μ B for Cu(II) complex , and from 2.69 μ B to 3.15 μ B for Nd(III) complex.
► The tetrad effect in the change of log
K
d
values was observed. ► The covalency in the lanthanide nitrato complexes is stronger than that in the chloride ones. ► The values of
μ
eff
(magnetic ...moments) for Ln–zeolite Y are much higher than those for Ln
3+ by Hund and Van Vleck.
The changes of the distribution constants
K
d
of lanthanide chlorides in the system: zeolite Y (solid phase)–sodium chloride (aqueous phase) were investigated. The evident tetrad effect in the change of log
K
d
values within the lanthanide series was observed and the attempt of its explanation through the comparison of covalence in Ln
O bonds existing in: the
Al
O(1/3Ln)
Si
,
Al
O(1/3Ln) species, i.e. those formed by siloxane and silanols in the zeolite phase and in the aquoions
Ln
(
H
2
O
)
8
–
9
3
+
present in the aqueous phase was presented. The Ln–zeolite samples were characterized by N
2 adsorption and magnetic measurements. The magnetic moments were determined over the range of 77–303
K. They obey the Curie–Weiss law. The values of
μ
eff
calculated for Ln–zeolite Y are much higher than those obtained for Ln
3+ by Hund and Van Vleck.
The complexes of 2,6-dimethoxybenzoic acid anion with ions of Co(II), Ni(II), and Cu(II)have been synthesized as polycrystalline solids, and characterized by elemental analysis, spectroscopy,magnetic ...studies, and also by X-ray diffraction and thermogravimetric measurements. The analysedcomplexes have following colours: pink for Co(II), green for Ni(II), and blue for Cu(II) compounds.The carboxylate group binds as monodentate, and bidentate bridging and chelating ligands. On heat-ing in air to 1173 K the complexes decompose in four, three or two steps. At first, they dehydrate inone or two steps to anhydrous salts, that next decompose to oxides of the respective metals. The solu-bility of the investigated dimethoxybenzoates in water at 293 K is of the order of 10 -2 mol/dm 3 . Theirmagnetic moments were determined in the temperature range of 76-303 K. The results reveal the com-pounds of Co(II) and Ni(II) to be high-spin complexes and that of Cu(II) to form dimer.
MCM-41 mesoporous material was chosen as a template of very small Fe3O4 particles. The results of structural and magnetic studies of magnetite nanowires are reported. The average length of these ...nanowires is about 70nm and their diameter is 3nm. Magnetite polycrystalline nanowires were characterized by means of X-ray diffraction and 57Fe Mössbauer spectroscopy (MS). Almost 80% of the particles exist in a superparamagnetic state at room temperature. Mössbauer measurements also provided evidence that the composites displayed a distribution of magnetic particles by size. As a result, strong changes of superparamagnetic and magnetic relative contributions along with temperature were observed.
The complexes of 3-methoxy-2-nitrobenzoates of Pr(III), Nd(III), Sm(III), Eu(III), Gd(III), Tb(III), Er(III) and Tm(III) with the formula: Ln(C8H6NO5)3·2H2O, where Ln=lanthanides(III), were ...synthesized and characterized by elemental analysis, Forier transform irtrared (FTIR) spectroscopy, magnetic and thermogravimetric studies and also by X-ray diffraction (XRD) measurements. The complexes had colours typical for Ln(III) ions. The carboxylate groups bound as bidentate chelating. On heating to 1173 K in air they decomposed in the same way, at first, dehydrated in one step to anhydrous salts, and then decomposed to the oxides of respective metals with intermediate formation of the oxycarbonates. The enthalpy values of the dehydration process changed from 133.72 to 44.50 kJ/mol. Their solubility in water at 293 K was of the order of 10−4 mol/dm3. The magnetic moments of analysed complexes were determined by Gouy's method in the range of 76-303 K.
The physicochemical properties of 2,4-, and 3,4-dimethoxybenzoates of Cu(II), Co(II) and Nd(III) were studied and compared to observe the -OCH3 substituent positions in benzene ring on the character ...of complexes. The analysed compounds are crystalline hydrated or anhydrous salts with colours depending on the kind of central ions: blue for Cu(II), pink for Co(II) and violet for Nd(III) complexes. The carboxylate groups bind as monodentate, bidentate bridging or chelating and even tridentate ligands. Their thermal stabilities were studied in air at 293-1173K. When heated the hydrated complexes release the water molecules and form anhydrous compounds which are then decomposed to the oxides of respective metals. Their magnetic moment values were determined in the range of 76-303K. The results reveal the compounds of Nd(III) and Co(II) to be the high-spin and that of Cu(II) forms dimer. The various positions of -OCH3 groups in benzene ring influence some of physicochemical properties of analysed compounds.
The complexes of 4-chlorophenoxyacetates of Mn(II), Co(II), Ni(II) and Cu(II) have been synthesized as polycrystalline 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: pink for Co(II), green for Ni(II), blue for Cu(II) and a pale pink for Mn(II) compounds. The carboxylate group binds as monodentate and bidentate ligands. On heating to 1173K in air the complexes decompose in several steps. At first, they dehydrate in one step to anhydrous salts, that next decompose to the oxides of respective metals. Their magnetic moments were determined in the range of 76-303K. The results reveal them to be high-spin complexes of weak ligand fields.
The complexes of 3-methoxy-2-nitrobenzoates of Pr（Ⅲ）, Nd（Ⅲ）, Sm（Ⅲ）, Eu（Ⅲ）, Gd（Ⅲ）, Tb（Ⅲ）, Er（Ⅲ） and Tm（Ⅲ） with the formula： Ln（C8H6NO5）3·2H2O, where Ln=lanthanides（Ⅲ）, were synthesized and ...characterized by elemental analysis, Forier transform irtrared （FTIR） spectroscopy, magnetic and thermogravimetric studies and also by X-ray diffraction （XRD） measurements. The complexes had col- ours typical for Ln（Ⅲ） ions. The carboxylate groups bound as bidentate chelating. On heating to 1173 K in air they decomposed in the same way, at first, dehydrated in one step to anhydrous salts, and then decomposed to the oxides of respective metals with intermediate formation of the oxycarbonates. The enthalpy values of the dehydration process changed from 133.72 to 44.50 kJ/mol. Their solubility in water at 293 K was of the order of 10-4 mol/dm3. The magnetic moments of analysed complexes were determined by Gouy＇s method in the range of 76-303 K.
The 2,3- and 3,5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II) were synthesized as solids and their magnetic, spectral and thermal properties studied. The complexes are hydrated or anhydrous ...compounds which possess colors typical of the M(II) ions. Their thermal stabilities were examined in air and nitrogen and the gaseous and solid state decomposition products were also identified. The magnetic susceptibilities of the complexes were measured over the temperature range 4.4?300 K and the magnetic moments were calculated. The results show that the 2,3- and 3,5-dimethoxybenzoates of Co(II) and Ni(II) are high-spin complexes with weak ligand fields, and that the complexes of Cu(II) form dimers.
Sintetizovani su Co(II), Ni(II) i Cu(II) 2,3- i 3,5-dimetoksibenzoati kao cvrste supstance i proucavana su njihova magnetna, termicka i spektralna svojstva. Dobiveni kompleksi su hidratisana ili anhidrovana jedinjenja boje tipicne za odgovarajuce M(II) jone. Termicka stabilnost odredjivana je u vazduhu i azotu, a identifikovani su cvrsti i gasoviti produkti razlaganja. Magnetna susceptibilnost merena je u temperaturnom opsegu 4,4 ? 300 K i izracunati su odgovarajuci magnetni momenti. Rezultati pokazuju da su 2,3- i 3,5- dimetoksibenzoati Co(II) i Ni(II) visokospinski kompleksi sa slabim poljem liganada, dok su kompleksi Cu(II) u obliku dimera.
The 2,3- and 3,5-dimethoxybenzoates of Co(II), Ni(II) and Cu(II) were synthesized as solids and their magnetic, spectral and thermal properties studied. The complexes are hydrated or anhydrous ...compounds which possess colours typical of the M(II) ions. Their thermal stabilities were examined in air and nitrogen and the gaseous and solid state decomposition products were also identified. The magnetic susceptibilities of the complexes weremeasured over the temperature range 4.4–300 K and the magnetic moments were calculated. The results show that the 2,3- and 3,5-dimethoxybenzoates of Co(II) and Ni(II) are high-spin complexes with weak ligand fields, and that the complexes of Cu(II) form dimers.
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