Search Results
Abstract
Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 4-methylphthalates were investigated and their composition, solubility in water at 295 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with molar ratio of metal to organic ligand of 1.0:1.0 and general formula: M [ CH3C6H3(CO2)2]nH2o (n=1-3) were recorded and their decomposition in air were studied. During heating the hydrated complexes are dehydrated in one (Mn, Co, Ni, Zn, Cd) or two steps (Cu) and next the anhydrous complexes decompose to oxides directly (Cu, Zn), with intermediate formation of carbonates (Mn, Cd), oxocarbonates (Ni) or carbonate and free metal (Co). The carboxylate groups in the complexes studied are mono- and bidentate (Co, Ni), bidentate chelating and bridging (Zn) or bidentate chelating (Mn, Cu, Cd). The magnetic moments for paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.92, 5.05, 3.36 and 1.96 M.B., respectively.
Abstract
Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)3,3-dimethylglutarates were investigated and their quantitative composition, solubility in water at 293 K and magnetic moments were determined. IR spectra and powder diffraction patterns of the complexes prepared with general formula MC7H10O4⋅nH2O (n=0−2) were recorded and their thermal decomposition in air were studied. During heating the hydrated complexes of Mn(II),Co(II), Ni(II) and Cu(II) are dehydrated in one step and next all the anhydrous complexes decompose to oxides directly (Mn, Co, Zn) or with intermediate formation free metal (Ni,Cu) or oxocarbonates (Cd). The carboxylate groups in the complexes studied are bidentate. The magnetic moments for the paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II)attain values 5.62, 5.25, 2.91 and 1.41 M.B., respectively.
Abstract
Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) 3-methyladipates were investigated and their qualitative composition and magnetic moments were determined. The IR spectra and powder diffraction patterns of the complexes prepared of the general formula M(C7H10O4)nH2O (n=0-11) were recorded and their thermal decomposition in air were studied. During heating the hydrated complexes are dehydrated in one (Co, Ni) or two steps (Mn, Zn) losing all crystallization water molecules (Co, Ni) or some water molecules (Mn, Zn) and then anhydrous (Co, Ni, Cu) or hydrated complexes (Mn, Zn) decompose directly to oxides (Mn, Co, Zn) or with intermediate formation the mixture of M+MO (Ni, Cu). The carboxylate groups are bidentate (Mn, Co, Ni, Cu) or monodentate (Zn). The complexes exist as polymers. The magnetic moments for the paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.48, 4.49, 2.84 and 1.45 B.M., respectively.
Abstract
Conditions for the preparation of Mn(II), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) 3-methoxy-4-methylbenzoates were investigated and their quantitative composition and magnetic moments were determined. The IR spectra and powder diffraction patterns of the complexes prepared of general formula M(C9H9O3)2 nH2O (n=2 for Mn, Co n=1 for Ni, Cu, n=0 for Zn, Cd) were prepared and their thermal decomposition in air was studied. Their solubility in water at 293 K is of the order 10–2 (Mn)–10–4 (Cu) mol dm–3. IR spectra of the prepared 3-methoxy-4-methylbenzoates suggest that carboxylate groups are bidentate bridging. The magnetic moments for the paramagnetic complexes of Mn(II), Co(II), Ni(II) and Cu(II) attain values 5.50, 4.45, 3.16 and 1.79 B. M., respectively. During heating the hydrated complexes lose crystallization water molecules in one step and then the anhydrous complexes decompose directly to oxides MO and Mn3O4. Only Co(II) complex decomposes to Co3O4 with intermediate formation CoO.
Complexes of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) with 4-chloro-2-methoxybenzoic acid anion
Physico-chemical properties
Abstract
The complexes of 4-chloro-2-methoxybenzoic acid anion with Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ were obtained as polycrystalline solids with general formula M(C8H6ClO3)2 nH2O and colours typical for M(II) ions (Mn – slightly pink, Co – pink, Ni – slightly green, Cu – turquoise and Zn – white). The results of elemental, thermal and spectral analyses suggest that compounds of Mn(II), Cu(II) and Zn(II) are tetrahydrates whereas those of Co(II) and Ni(II) are pentahydrates. The carboxylate groups in these complexes are monodentate. The hydrates of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) heated in air to 1273 K are dehydrated in one step in the range of 323–411 K and form anhydrous salts which next in the range of 433–1212 K are decomposed to the following oxides: Mn3O4, CoO, NiO and ZnO. The final products of decomposition of Cu(II) complex are CuO and Cu. The solubility value in water at 293 K for all complexes is in the order of 10–3 mol dm–3. The plots of χM vs. temperature of 4-chloro-2-methoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II) follow the Curie–Weiss law. The magnetic moment values of Mn2+, Co2+, Ni2+ and Cu2+ ions in these complexes were determined in the range of 76−303 K and they change from: 5.88–6.04 μB for Mn(C8H6ClO3)24H2O, 3.96–4.75 μB for Co(C8H6ClO3)25H2O, 2.32–3.02 μB for Ni(C8H6ClO3)25H2O and 1.77–1.94 μB for Cu(C8H6ClO3)24H2O.
Abstract
Four new complexes of 2,3,4-trimethoxybenzoic acid anion with manganese(II), cobalt(II), nickel(II) and copper(II) cations were synthesized, analysed and characterized by standard chemical and physical methods. 2,3,4-Trimethoxybenzoates of Mn(II), Co(II), Ni(II) and Cu(II) are polycrystalline compounds with colours typical for M(II) ions. The carboxylate group in the anhydrous complexes of Mn(II), Co(II) and Ni(II) is monodentate and in that of Cu(II) monohydrate is bidentate bridging one. The anhydrous complexes of Mn(II), Co(II) and Ni(II) heated in air to 1273 K are stable up to 505–517 K. Next in the range of 505–1205 K they decompose to the following oxides: Mn3O4, CoO, NiO. The complex of Cu(II) is stable up to 390 K, and next in the range of 390–443 K it loses one molecule of water. The final product of its decomposition is CuO. The solubility in water at 293 K is of the order of 10–3 mol dm–3 for the Mn(II) complex and 10–4 mol dm–3 for Co(II), Ni(II) and Cu(II) complexes. The magnetic moment values of Mn2+, Co2+, Ni2+ and Cu2+ ions in 2,3,4-trimethoxybenzoates experimentally determined in the range of 77–300 K change from 5.64–6.57 μB (for Mn2+), 4.73–5.17 μB (for Co2+), 3.26–3.35 μB (for Ni2+) and 0.27–1.42 μB (for Cu2+). 2,3,4-Trimethoxybenzoates of Mn(II), Co(II) and Ni(II) follow the Curie–Weiss law, whereas that of Cu(II) forms a dimer.
]. Magnetic moments, electronic and EPR spectra The magnetic moments for all complexes were determined at room temperature, using the diamagnetic correction [ 27 ] ( Eq. 1 ): 1 where M is the molecular weight of the compound and k a factor
equipped with an E101 microwave bridge. Magnetic moments were determined on a Johnson Mathey magnetic susceptibility balance. The thermal analysis (TG and DTA) of the solid complexes was performed using Shimadzu TG-50 thermal analyzer in the temperature
Abstract
Physico-chemical properties of 4-chloro-2-nitrobenzoates of Co(II), Ni(II), and Cu(II) were studied. The complexes were obtained as mono- and trihydrates with a metal ion to ligand ratio of 1:2. All analysed 4-chloro-2-nitrobenzoates are polycrystalline compounds with colours depending on the central ions: pink for Co(II), green for Ni(II), and blue for Cu(II) complexes. Their thermal decomposition was studied only in the range of 293–523 K, because it was found that on heating in air above 523 K 4-chloro-2-nitrobenzoates decompose explosively. Hydrated complexes lose crystallization water molecules in one step and anhydrous compounds are formed. The final products of their decomposition are the oxides of the respective transition metals. From the results it appears that during dehydration process no transformation of nitro group to nitrite takes place. The solubilities of analysed complexes in water at 293 K are of the order of 10–4–10–2 mol dm–3. The magnetic moment values of Co2+, Ni2+ and Cu2+ ions in 4-chloro-2-nitrobenzoates experimentally determined at 76–303 K change from 3.89 to 4.82 μB for Co(II) complex, from 2.25 to 2.98 μB for Ni(II) 4-chloro-2-nitrobenzoate, and from 0.27 to 1.44 μB for Cu(II) complex. 4-chloro-2-nitrobenzoates of Co(II), and Ni(II) follow the Curie–Weiss law. Complex of Cu(II) forms dimer.
