On the relationship between the structures of Cu(II) complexes and their chemical transformations

The experimental activation energies (E ^*) of dehydration of Cu(NH₃)₄(H₂O)SO₄, Cu(en)₂(H₂O)X₂ (X=Cl^?, Br^?), Cu(en)(H₂O)₂SO₄, Cu(py)₂(H₂O)₂SO₄, CuCl₂ · 2H₂O and M ₂ ^I CuCl₄ · 2H₂O (M ^I =NH₄, K, Rb) were obtained from their non-isothermal thermogravimetric curves using the Coats-Redfern method. TheseE ^* values were compared with known data on the structures of the Cu(II) coordination polyhedra in the above complexes. No dependence of theE ^* values was found on either the central atom — released ligand bond length, or the number and lengths of the hydrogen bonds formed by the released water molecules. However, it was found that it is justified to seek some relationship between theE ^* values and the anisotropic temperature factors of the donor atoms of the ligands split off.     

Variable temperature PXRD investigation of the phase changes during the dehydration of potassium Tutton salts

The thermal dehydration of the potassium Tutton salts K₂M(SO₄)₂·6H₂O (M = Mg, Co, Ni, Cu, Zn) was investigated using thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), FTIR, and variable temperature powder X-ray diffraction. While each Tutton salts lost all six waters of hydration when heated to 500 K, the decomposition pathway depended on the divalent metal cation. K₂Ni(SO₄)₂·6H₂O lost all six waters in a single step, and K₂Cu(SO₄)₂·6H₂O consistently lost water in two steps in capped and uncapped cells. In contrast, multiple decomposition pathways were observed for the magnesium, cobalt, and zinc Tutton salts when capped and uncapped TG cells were used. K₂Zn(SO₄)₂·6H₂O lost the waters of hydration in a single step in an uncapped cell and in two steps in a capped cell. Both K₂Mg(SO₄)₂·6H₂O and K₂Co(SO₄)₂·6H₂O decomposed in a series of steps where the stability of the intermediates depended on the cell configuration. A greater number of phases were often observed in DSC and capped-cells TG experiments. A quasi-equilibrium model is presented that could explain this observation. These results highlight that experimental conditions play a critical role in the observed thermal decomposition pathway of Tutton salts.     

Coordination‐directed and Hydrogen‐bonded Assembly of Supramolecular Architectures Constructed from Diverse Coordination of Linear,Triangular, Tetragonal Pyramid,Trigonal Bipyramid,and Octahedral Mononuclear Units

Reaction of a imidazole phenol ligand 4‐(imidazlo‐1‐yl)phenol (L) with 3d metal salts afforded four complexes, namely, [Ni(L)₆] · (NO₃)₂ ( 1 ), [Cu(L)₄(H₂O)] · (NO₃)₂ · (H₂O)₅ ( 2 ), [Zn(L)₄(H₂O)] · (NO₃)₂ · (H₂O) ( 3 ), and [Ag₂(L)₄] · SO₄ ( 4 ). All complexes are composed of monomeric units with diverse coordination arrangements and corresponding anions. All the hydroxyl groups of monomeric cations are used as hydrogen‐bond donors to form O–H ··· O hydrogen bonds. However, the coordination habit of different metal ions produces various supramolecular structures. The Ni^II atom shows octahedral arrangement in 1 , featuring a 3D twofold inclined interpenetrated network through O–H ··· O hydrogen bond and π–π stacking interaction. The Cu^II atom of 2 displays square pyramidal environment. The O–H ··· O hydrogen bond from the [Cu(L)₄(H₂O)]²⁺ cation and lattice water molecule as well as π–π stacking produce one‐dimensional open channels. NO₃^– ions and lattice water molecules are located in the channels. 3 is a 3D supramolecular network, in which Zn^II has a trigonal bipyramid arrangement. Two different rings intertwined with each other are observed. The Ag^I in 4 has linear and triangular coordination arrangements. The mononuclear units are assembled into a 1D chain by hydrogen bonding interaction from coordination units and SO₄^2– anions.     

Derivatographic studies on dehydration of salt hydrates and their deuterium oxide analogues. VI

Non-isothermal studies of the dehydration of double salt hydrates of the type K₂AB₄·M(II)SO₄·6H₂O where AB₄BeF^2?₄ or SeO^2?₄ and M(II)Mg(II), Co(II), Ni(II), Cu(II) or Zn(II) and their D₂O analogues were carried out. Thermal parameters like activation energy, order of reaction, enthalpy change, etc., for each step of dehydration were evaluated from the analysis of TG, DTA and DTG curves. These parameters were compared with the corresponding double sulphate, i.e., K₂SO₄·M(II)SO₄·6H₂O and their D₂O analogues. The role of divalent cation on the thermal properties of dehydration of the salt hydrates and also the effect on the thermal properties due to deuteration were discussed. The order of reaction was always found unity. The values of ΔH were within ～11-～19 kcal mol^?1     

Crystal and molecular structure and ion selective and complexing properties of 1,5-bis[2-(dioxyphosphoryl-4-methoxy)phenoxy]-3-oxapentane dihydrate [(OH)2(O)P(C6H3OCH3)(OCH2CH2)2 O(C6H4OCH3)P(O)(OH)2] · 2H2O

Ion selective and complexing properties of 1,5-bis[2-(dioxyphosphoryl-4-methoxy)phenoxy]-3-oxapentane dihydrate H₄M² · 2H₂O (I) were described. X-ray diffraction analysis for compound I was performed. The crystals are orthorhombic, a = 7.9818(16) ?, b = 30.553(6) ?, c = 9.0559(17) ?, V = 2208.5(8) ?³, Z = 4, space group Pnma, R = 0.0500 over 1372 reflections with I > 2??(I). In I, the H₄M² molecules are combined by hydrogen bonds (HB) with two crystallographically independent H₂O(7) and H₂O(8) molecules to give neutral H₄M² · 2H₂O aggregates. The HB between the phosphoryl and hydroxyl oxygen atoms of the aggregates and the donor O(7)-H??O(8) HB give rise to a layered structure. Conclusions about the Cu(H₂M²) compound structure were drawn based on the X-ray diffraction, DTA, and vibrational spectroscopy data.     

Spectrophotometric and thermal analytical studies on the dehydration of copper(II) sulfate and its double salts

Spectrophotometric (diffuse reflection) and TG-DTA data on the dehydration of CuSO₄ · 5H₂O, Na₂Cu(SO₄)₂ · 2H₂O, M₂Cu(SO₄)₂ · 6H₂O(M⁺ = K⁺, Rb⁺, Cs⁺ and NH⁺₄) and Co₂Cu(SO₄)₃ · 18H₂O are given. Although complete dehydration of CuSO₄ · 5H₂O brings about a striking color change from blue to white, it was found that there is only a slight decrease in the v?_max. of its d-d band in the course of this change, and the total light absorption in the visible-UV region increases at the same time. The dehydration of the alkali metal and ammonium double salts, most of which contain [Cu(OH₂)₆]²⁺ aquo ions (in contrast to the [Cu(OH₂)₄]²⁺ in CuSO₄ · 5H₂O), occurs generally more easily than that of CuSO₄ - 5H₂O, and their v?_max. increases slightly in the change, leading to blue or green anhydrous products, although the formation of a white modification was observed with the potassium salt. It was also found that the v?_max. of the Cu²⁺ ion in the dehydrated cobalt(II) double salt is still lower than that in anhydrous CuSO₄, i.e., the ligand field and/or tetragonality around it is decreased by the presence of Co²⁺ ions.     

Ion-selective properties of 1,8-bis [2-(dihydroxyphosphinyl)phenoxy]-3,6-dioxaoctane (H4L3), synthesis and vibrational spectra of copper and zinc complexes with H4L3, and crystal and molecular structure of [Cu(H4L3)(H2O)3][(H2L3)(H2O)]

The ion-selective properties of 1,8-bis[2-(dihydroxyphosphinyl)phenoxy]-3,6-dioxaoctane (H₄L³) have been studied and its potentiometric selectivity coefficients have been determined. New complexes [Cu(H₄L³)(H₂O)₃][(H₂L³)(H₂O)] (I) and Zn(H₄L³)(H₂L³) · 3H₂O, and Cu(H₂L³) · 2(H₂O) have been synthesized and characterized. The crystal and molecular structure of I has been determined by X-ray crystallography and vibrational spectroscopy. The crystals are monoclinic, a = 10.279(5) Å, b = 26.532(13) Å, c = 8.399(4) Å, β = 99.270(8)°, V = 2260.8(7) ų, Z = 2, space group Cm, R = 0.0347 for 4325 reflections with I > 2σ(I). Ionic compound I is composed of the [Cu(H₄L³)(H₂O)₃]²⁺ complex cations and [(H₂L³)(H₂O)]^2? anions. In the cation, the Cu²⁺ cation located in the m plane is bound to a tetragonal pyramidal (TP) array. The equatorial plane of the TP is formed by two phosphoryl oxygen atoms of the podand (Cu(1)-O, 1.921(2) Å) and two O atoms of two water molecules (av. Cu(1)-O, 1.981(3) Å). The third water molecule is at the axial vertex of the TP at a considerably larger distance (Cu(1)-O, 2.139(3) Å). The anion is of the host-guest type. The host is the deprotonated podand (H₂L³)^2?, and the guest is the water molecule. The latter is bound to the terminal hydroxyl groups of two phosphoryl groups of the podand by two acceptor hydrogen bonds and to two central ether oxygen atoms of the (H₂L³)^2? anion by one donor bifurcated hydrogen bond. The cations and anions in the structure are linked by hydrogen bonds to form chains parallel to the c axis.     

Mechanism and kinetics of formation and decomposition of carnallitic double salts

Insufficient thermochemical data are available on the carnallitic double salts M¹MgX ₃·6H₂O (M=Li (H₂O), K, Rb, Cs, NH₄;X=Cl. Br, I). In the present work, findings relating to the salt paragenesis are given on the basis of solution-calorimetric measurements. The melting and decomposition behaviour is characterized by means of DTA and thermogravimetric investigations under quasiequilibrium conditons. Except for Li(H₂O) Cl·MgCl₂·6H₂O, the decomposition of the chloridic carnallitic double salts always proceeds via the intermediate stage of the corresponding dihydrate. For each of the different anions, a linear correlation is found between the degree of hydrolysis of the hydrate water-free final products and the radii of the monovalent cations.     

Crystal structure of a new supramolecular Ni(II) N 6-benzylaminopurine compound

A new mononuclear Ni(II) N ⁶-benzylaminopurine supramolecule [Ni(6-BA-H₂)₂(H₂O)₄]·(R)₂·4H₂O (1) (6-BA = N ⁶-benzylaminopurine (C₅H₂N₃NH)(NH)CH₂(C₆H₅), H₃R = 5-sulfosalicylic acid (C₆H₃)CO₂H· (OH)SO₃H) is firstly synthesized by the volatile method. Compound 1 possesses a 3D supramolecular structure built via H-bonds and π-π stacking interactions. In the structure, a mononuclear [Ni(6-BA-H₂)₂(H₂O)₄]⁶⁺ cation, in which the Ni(II) ion is 6-coordinated, bears six positive charges, and a fully deprotonated R^3? anion is located in the void surrounding the mononuclear cation to balance the charge.     

Bi-, TRI- and Penta-Nuclear Complexes of Chelating Schiff Bases Derived from o-Acetoacetylphenol and Amine Complexes, [Ni(1,2-pn)2Cl2]·3H2O and [Cu(1,2-pn)2]SO4·2H2O

Two novel macroacylic Schiff base ligands were prepared by condensation of two diamine metal complexes, [Ni(1,2-pn)₂Cl₂]·3H₂O and [Cu(1,2-pn)₂]SO₄·2H₂O with o-acetoacetylphenol. The ligands MH₆L(M = Ni or Cu) are hexabasic and contain two O₄ coordination sites. They act as ligands towards transition metal ions yielding homo- and heteronuclear complexes of the type [NiH₄ LCu(H₂O)₂]·4H₂O, [MH₂LM' ₂(H₂O)₆], [MLM' ₄(H₂O)₈], [MH₂ LCe₂(NO>₃)₂(H₂O)₂] and [NiLTh₂(NO₃)₂(H₂O)₂] (M = Ni or Cu; M' = Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ce(III), Th(IV) and UO₂ (VI)). The complexes were characterized by elemental analysis, thermogravimetric analysis (TGA), IR, visible and ESR spectra, magnetic susceptibility measurements and mass spectrometry. Magnetic moments were altered by the introduction of metal cations besides the one already present in the complex ligands. The M' cations were linked to two ketonic oxygen atoms and two phenyl oxygen atoms in [NiH₆ L(H₂O)₂] and [CuH₆ L] complex ligands. All homo- and hetero-, bi- and tri-nuclear complexes show antiferromagnetic interactions which are attributed to inter- or intramolecular interactions of the metal cations. Mass spectra of the complex ligands and selected homo- and heteronuclear complexes support the formula weights of these complexes. Visible and ESR spectra as well as magnetic moments indicated that the parent mononuclear complex ligands [MH₆ L] have an octahedral geometry for Ni(II) and a square-planar geometry distorted towards tetrahedral for Cu(II). The metal cations in bi-, tri- and pentanuclear complexes are octahedral or square-planar. The octahedral configuration is completed by chloride anions and/or solvent molecules.     

Crystal structure of copper(II) cimetidine sulphate nonahydrate. Cation distortion and structure isomerism in three copper(II) cimetidine complexes

In the crystalline state, the complex [Cu(CM)₂]SO₄·9H₂O (CM = cimetidine) is constituted of two-dimensional cations[Cu(CM)₂²⁺]_n separated by SO₄²⁻ anions and water molecules. As in the related complexes [Cu(CM)₂](ClO₄)₂ and [Cu(CM)₂](NO₃)₂, the copper atom lies in a strongly distorted octahedral CuN₄S₂ environment. The distortion is quite different from one complex to another (cation distortion isomerism). In the title compound the CuS bond is unusually long (2.91 Å). Unlike the title compound, the [Cu(CM)₂²⁺]_n cations in the perchlorate and nitrate salts are one-dimensional infinite chains characterized by different conformations of the cimetidine molecules (cation structure isomerism).     

Derivatographic studies on dehydration of salt hydrates and their deuterium oxide analogues. V

Non-isothermal thermal studies of the dehydration of the double salt hydrates of the type M(I)₂SO₄·M(II)SO₄·6H₂O and their D₂O analogues were carried out where M(I) = TI(I) and M(II) = Mg(II), Co(II), Ni(II), Cu(II) or Zn(II). Thermal parameters like activation energy, order of reaction, enthalpy change, etc. were evaluated from the analysis of TG, DTA and DTG curves. These thermal parameters were compared with those of other series, like NH₄(I), K(I), Rb(I) and Cs(I) studied earlier. On deuteration the nature of dehydration altered in the case of Tl₂Zn(SO₄)₂·6H₂O only. The thermal stability of the salt hyd discussed in relation to the salt hydrates of other series. The role of divalent cation on the thermal properties of dehydration of salt hydrates is also discussed. The order of reaction was always found unity. The values of ΔH were within ≈12–≈16 kcal mol^?1.     

Synthesis,structures and thermal properties of Cu(II) and Ni(II) complexes containing diethylenetriamine and nicotinate ligands

The syntheses and crystal structures of four new divalent transition metal complexes of the types [Cu₂(dien)₂(nic)](ClO₄)₃ · MeOH (nic = anion of nicotinic acid; dien = diethylenetriamine), 1; [Cu(dien)(nic)]₂(nic)₂, 2; [Cu(dien)(nic)]₂(BF₄)₂ · 2MeOH, 3 and [Ni(dien)(nic)(H₂O)]₄(NO₃)₄ · 2MeOH, 4, are reported, which were prepared by the reactions of diethylenetriamine and nicotinic acid with Cu(ClO₄)₂ · 6H₂O, Cu(OAc)₂ · H₂O, Cu(BF₄)₂ · 6H₂O and Ni(NO₃)₂ · 6H₂O in MeOH, respectively. These complexes were characterized by single-crystal X-ray diffraction method and elemental analyses. In the cation of complex 1, one nicotinate ligand bridges two Cu(II) metal centers through the pyridyl nitrogen atom and one of the carboxylate oxygen atoms. The cations of complexes 2 and 3 form the twelve-membered metallocycles, involving two Cu(II) ions that are bridged by two nicotinate ligands. The cation of complex 4 forms a tetranuclear cage with the four Ni(II) metal centers bridged by four nicotinate ligands and each Ni(II) metal center adopts the distorted octahedral geometry. Their thermal properties have been investigated by using differential scanning calorimetry (DSC) and thermogravimetric analyses (TGA).     

3-(diallylamino)propanenitrile ((C3H5)2NC2H4CN, L) π-complexes with copper(I) ionic salts. Syntheses and crystal structures of compounds [Cu(H+L)ClO4]ClO4 · H2O, [Cu(H+L)BF4]BF4 · H2O, and [Cu(H+L)(H2O)]SiF6 · H2O

Qualitative single crystals of ??-complexes Cu(H⁺L)(ClO₄)]ClO₄ · H₂O (I), Cu(H⁺L)(BF₄)]BF₄ · H₂O (II), and [Cu(H⁺L)(H₂O)]SiF₆ · H₂O (III) are synthesized from solutions of 3-(diallylamino)propanenitrile (L) in propanol, ethanol, and methanol-water acidified with the corresponding acid to pH 3.5?C5 and from the copper(II) salts (Cu(ClO₄)₂ · 6H₂O, Cu(BF₄)₂ · 6H₂O, and CuSiF₆ · 4H₂O) using the alternating-current electrochemical method on copper wire electrodes. The crystal structures of the complexes are determined. All compounds crystallize in the monoclinic crystal system: complexes I and II are isostructural, space group P2₁/n, Z = 4. For compound III, space group P2₁/c, Z = 8. Unit cell parameters: for I a =7.8153(3), b = 16.7824(7), c = 12.4426(5) ?, ?? = 93.410(2)°, V = 1629.1(1) ?³; for II, a = 7.6755(4), b = 16.7119(7), c = 12.3784(6) ?, ?? = 94.354(2)°, V = 1583.2(1); and for III a = 9.826(2), b = 24.009(3), c = 12.061(2) ?, ?? = 91.820(6)°, V = 2843.9(7) ?³. The trigonal pyramidal coordination of the copper atom in complexes I-III is formed by two C=C bonds of the allyl groups of H⁺L, the nitrile N atom of the adjacent cation of the ligand, and the O or F atom of the ClO ₄ ^? or BF ₄ ^? anions. In structure III, the apical position of the pyramid is occupied by the O atom of the water molecule, since the SiF ₆ ^2? anion is considerably remote from the copper(I) atom. However, this anion is bound to the organic cation by hydrogen bonds F??H (2.05?C2.51 ?).     

Synthesis and study of cobalt(II), nickel(II), and copper(II) complexes with 4-(4-hydroxyphenyl)-1,2,4-triazole

New complexes of Co(II), Ni(II), and Cu(II) nitrates, chlorides, and perchlorates with 4-(4-hydroxyphenyl)-1,2,4-triazole (L) were obtained and examined by single-crystal X-ray diffraction, X-ray powder diffraction, and electronic absorption and IR spectroscopy. The cations of all the complexes have linear trinuclear structures. Ligand L is coordinated to the metal ions in a bidentate bridging fashion through the N(1) and N(2) atoms of the heterocycle. The coordination polyhedron of the metal atoms is a distorted octahedron. The molecular and crystal structures of the complexes [Co₃L₆(H₂O)₆](ClO₄)₆ · 3C₂H₅OH · 3.75H₂O and [M₃L₆(H₂O)₆](ClO₄)₆ · 6H₂O (M = Cu²⁺ and Ni²⁺) were determined.     

The solid state reactions of o-aminobenzoic acid with Zn(Ⅱ), Cu(Ⅱ), Ni(Ⅱ), Mn(Ⅱ) acetate hydrate at room temperature

The solid-solid state reactions of o-aminobenzoic acid with Zn(OAc)2.2H2O, Cu(OAc)2 .H2O, Ni(OAc)2.4H2O and Mn(OAc)2.4H2O result in the formation of corresponding complexes M(OAB)2 (M = Zn(Ⅱ), Cu(Ⅱ), Ni(Ⅱ), Mn(IⅡ)). XRD, IR and elemental analysis methods have been used to characterize the solid products. The activation energies of these reactions, which are calculated from the kinetic data obtained by means of the isothermal electrical conductivity measurement method, have been found to increase in the order: Cu(OAc)2.H2O(37.7 kJ.mol-1)~Mn(OAc)2.4H2O (39.7kJ.mol-1) < Zn(OAc)2.2H2O (56.3 kJ.mol-1) < Ni(OAc)2.4H2O (85.2 kJ.mol-1). The trend is related to their crystal structures.     

Coordination compounds of cobalt, nickel, copper and zinc with thiosemicarbazone and 3-phenylpropenal semicarbazone

Hydrates of 3-phenylpropenal thiosemicarbazone (HL·H₂O) and semicarbazone (HL′·H₂O) react in methanol with cobalt, nickel, copper, and zinc chlorides, nitrates, and acetates to form coordination compounds MX₂·2HL·nSolv [M = Co, Ni, Cu, Zn; X = Cl, NO₃; HL = C₆H₅CH=CH-CH=N-NHC(O)NH₂; n = 0–3; Solv = H₂O, CH₃OH], CuX₂·HL·nH₂O [M = Ni, Cu; n = 0, 1], ML₂·nH₂O and ML′·nH₂O [M = Co, Ni, Zn; HL′ = C₆H₅CH=CH-CH=N-NHC(O)NH₂; n = 0–3]. In the presence of amines (A = C₅H₅N, 2-CH₃C₅H₄N, 3-CH₃C₅H₄N, and 4-CH₃C₅H₄N) these reactions yield the complexes Cu(A)LCl·CH₃OH and M(A)LX·nH₂O [M = Cu, Ni; X = Cl, NO₃; n = 0–2]. The copper complexes with the amine ligands are of polynuclear structure, and other complexes are monomeric. Carbazones (HL and HL′) are included in the complexes as bidentate N,S-and N,O-ligands. The thermolysis of the complexes involves the stages of removing solvent crystallization molecules (70–90°C), deaquation (150–170°C), and full thermal decomposition (500–580°C).     

The relationship between the structures of Cu(II) complexes and their chemical transformations

The thermal dehydration of the compounds M ₂ ^I [M^II(H₂O)₆](SeO₄)₂, where M^I=NH₄, K, Rb, Cs and Tl, and M=Cu and Ni, was studied in order to correlate the course of the decomposition with the known crystal structures. It was found that the stoichiometry of the reactions is the same as that established for the analogous sulphato compounds of Cu(II) and Ni(II), respectively. Because of the discrepancies between the room-temperature crystal structures and the observed decomposition stoichiometries, high-temperature powder diffractograms were taken. These indicated structural changes of the copper(II) compounds during heating. The powder patterns for different structure changes were calculated and compared with the experimental ones. It was shown that during the heating two axial CuH₂O bonds are shortened and two equatorial bonds are lengthened. The observed decomposition stoichiometry is compatible with the formation of four nearly equal Cu-H₂O bonds. The activation energies (E^*) and pre-exponential factors (log A) for the first dehydration reaction of the Cu(II) compounds display the following sequence of M^I: Tl > Rb > NH₄ > K, and they are the higher, the shorter the split equatorial Cu(II) bonds. For the compounds of Ni(II) the sequence of E^* and log A values is K > Tl > NH₄ > Rb > Cs.

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Zusammenfassung Zur Aufklärung des Zusammenhanges zwischen dem Zersetzungsweg und der bekannten Kristallstruktur wurde die thermische Dehydration der Verbindungen M ₂ ^I [M^II(H₂O)₆](SeO₄)₂ mit M^I=NH₄, K, Rb, Cs and Tl sowie mit m^II=Cu und Ni untersucht. Man fand für diese Reaktion die gleiche Stöchiometrie wie für die analogen Sulfatverbindungen von Cu(II) bzw. Ni(II). Wegen des Widerspruches zwischen der Kristallstruktur bei Raumtemperatur und der festgestellten Stöchiometrie der Zersetzungsreaktion wurden auch Pulverdiffraktionsaufnahmen bei höheren Temperaturen angefertigt. Bei Cu(II)-Verbindungen konnte während des Erhitzens eine Strukturänderung festgestellt werden. Für verschiedene Strukturänderungen wurden Pulveraufnahmen berechnet und mit den experimentellen verglichen. Es konnte gezeigt werden, da sich während des Erhitzens zwei axiale Cu-H₂O-Bindungen verkürzen und zwei äquatoriale Bindungen strecken. Die beobachtete Zersetzungsstöchiometrie entspricht der Bildung von vier anänhernd gleichen Cu-H₂O-Bindungen. Die Aktivierrungsenergie (E^*) und der präexponentielle Faktor (log A) und der ersten Dehydratationsreaktion der Cu(II)-Verbindungen sinken in folgender Reihenfolge für M^I:Tl, Rb, NH₄, K und sind umso größer, je kürzer die gespaltenen äquatorialen Cu(II)-Bindungen sind. Für Ni(II)-Verbindungen nehmen E^* und log A in folgenden Reichenfolge ab: K, Tl, NH₄, Rb, Cs.

     

Role of interlayer M k atoms and H2O molecules in the structure formation of M k (VUO6) k · nH2O uranovanadates

M ^k (VUO₆) _k · nH₂O uranovanadates of alkali (Li, Na, K, Rb, Cs), alkaline-earth (Mg, Ca, Sr, Ba), 3d transition (Mn, Fe, Co, Ni, Cu, Zn), and rare-earth (Y, La, Ln) elements were prepared by precipitation from solutions under hydrothermal conditions and in solid-phase reactions. The composition and structure of these compounds and the role of M ^k atoms and H₂O molecules in the formation of their structure were studied by X-ray diffraction, IR-spectroscopy, thermal analysis, and chemical analysis.     

Novel complexes of Co2+, Ni2+, and Cu2+ with N-(phosphonomethyl)aminosuccinic acid

Complexes of Co²⁺, Ni²⁺, and Cu²⁺ with N-(phosphonomethyl)aminosuccinic acid (H₄PMAS) of general formula Na₂MPMAS·nH₂O [M=Co(II), Ni(II), Cu(II), n—number of water molecules] were synthesized. Based on interpretation of diffusion reflectance spectroscopy, structure of all complexes is based on distorted octahedral. Analysis of IR spectra of Co(II), Ni(II), and Cu(II) N-(phosphonomethyl)aminosuccinates demonstrated that metal ions are coordinated to the ligand through nitrogen atom of the imino group, oxygen atoms of the α- and β-carboxyl groups as well as oxygen atom of the phosphonic group of the H₄PMAS. We demonstrated that thermal stability of complexes increases in sequence Cu(II) < Ni(II) < Co(II), obviously as a result of change over from the dimeric to polymeric character of the initial complex. Complete decomposition of ligand occurs at these temperatures and is accompanied by release of H₂O, CO₂, and NO₂. The final products of thermal decomposition of the complexes are mixtures of oxides and phosphates of respective metals.