Solvation of bivalent transition metalcations. II. Heats of transfer of metal perchlorates between water and several amides

Heats of solution of acetonitrile, solvated or hydrated perchlorates, Mn(ClO₄)₂·6AN, Co(ClO₄)₂·6AN, Ni(ClO₄)₂·6AN, Cu(ClO₄)₂·4AN, Cu(ClO₄)₂·6H₂O, Zn(ClO₄)₂·6AN, and Zn(ClO₄)₂·6H₂O have been determined in NMF, DMF, DMA, and water. Complete or almost complete exchange of AN and water molecules in amides is inferred from the visible spectra determinations. The heats of transfer of perchlorate anion from water to DMA and NMF have been obtained from separately determined heats of solution of NaBPh₄, AsPH₄Cl·H₂O, NaClO₄, NaCl, and SiPh₄ in the respective solvents. The heats of transfer of cations from water to amides have been determined from the above data and the heats of solvation of cations using literature data for the heats of hydration.     

Electrical conductance and ionic association of the bivalent transition metal tetrafluoroborates in acetonitrile solution

Visible absorption spectra of Co(BF₄)₂ and Ni(BF₄)² in acetonitrile (AN) indicate the existence of complex electrolytes solely of the type [M(AN)₆]²⁺·2BF ₄ ^– . Close agreement of the molar conductance curves for Mn(BF₄)₂, Co(BF₄)₂, Ni(BF₄)₂, Cu(BF₄)₂, and Zn(BF₄)₂ indicates that the same is true for the other tetrafluoroborates as well. Small specific differences in properties of the [M(AN)₆]²⁺ complex cations are reflected in the limiting molar conductances, while the first-step association constants to a good approximation are the same for the different metal cations. Penetration of the tetrafluoroborate anion in between the coordinated acetonitrile molecules is suggested as a possible explanation for the apparent independence of ionic association on the crystallographic radius of the cation.     

Structural,spectroscopic and redox properties of transition metal complexes of dipyrido[3,2-f:2′,3′-h]-quinoxaline (dpq)

The chemistry of first row transition metal complexes obtained from the ligand dipyrido[3,2-f:2′,3′-h]-quinoxaline (dpq) have been reported. The reaction between Cu(ClO₄)₂ · 6H₂O with dpq under different reaction conditions led to the isolation of three polymorphic copper(II) complexes [Cu(dpq)₂(H₂O)](ClO₄)₂ · H₂O (2), [Cu(dpq)₂(ClO₄)](ClO₄) (3) and [{Cu(dpq)₂(H₂O)}{Cu(dpq)₂(ClO₄)}](ClO₄)₃ (4). The bluish-green compound 2, obtained by reacting Cu(ClO₄)₂ · 6H₂O with dpq in methanol, has a distorted trigonal bipyramidal structure with τ = 0.55. The reaction between Cu(ClO₄)₂ · 6H₂O and dpq in dry acetonitrile produced the blue compound 3 in which the copper(II) centre has a distorted square planar geometry. When the condensation reaction between 1,10-phenanthroline-5,6-dione and 1,2-diaminoethane was carried out in the presence of Cu(ClO₄)₂ · 6H₂O in methanol, the green copper(II) complex 4 was isolated along with 1. The structure determination of 4 has established the presence of two different complex cations in the asymmetric unit and they are considered as co-crystals. In the zinc(II) compound [Zn(dpq)₂(ClO₄)₂] (5), the two perchlorates are unidentately coordinated to the metal centre, providing a distorted octahedral geometry. The quinoxaline ring in 5 is involved in intermolecular π–π interactions, leading to the generation of a sinusoidal chain. The proton NMR spectra, especially those of the paramagnetic complexes [Ni(dpq)₃](ClO₄)₂ (6) and [Co(dpq)₃](ClO₄)₂ (7), have been studied in detail. The electronic absorption spectra and the redox behaviour of the copper(I), copper(II), cobalt(II) and cobalt(III) complexes have been studied. The three copper(II) compounds 2–4 show identical absorption spectra and redox properties when measured in acetonitrile, although in nitromethane they show small but definite differences in their spectral and redox features.     

Thermochemical properties of anhydrous and hydrated alkaline-earth metal and magnesium perchlorates

A low-temperature method of obtaining anhydrous magnesium, calcium, strontium, and barium perchlorates and their hydrates was developed. Hexa-Mg(ClO₄)₂, Sr· (ClO₄)₂·H₂O, and Ba(ClO₄)₂·H₂O were prepared for the first time. The enthalpies of dissolution of anhydrous magnesium and strontium perchlorates and Mg, Ca, Sr, and Ba perchlorate hydrates in water were measured; the standard enthalpies of their formation were determined. The enthalpies of dehydration of M(ClO₄)₂· nH₂O in stages were determined.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 1978–1983, September, 1989.     

Water vapor pressure and thermodynamics of dehydration of Group 2 perchlorate hydrates

The limits of existence for Group 2 perchlorate hydrates are defined. The water vapor pressure is measured over the crystal hydrates Mg(ClO₄)₂·2H₂O, Ca(ClO_{4 2}·4H₂O, Sr(ClO₄)₂·3H₂O, Sr(ClO₄)₂·2H₂O, Sr(ClO₄)₂·H₂O, Ba(ClO₄)₂·3H₂O, and Ba(ClO₄)₂·H₂O. The water vapor pressure and thermodynamics constants of dehydration depend directly on the electron-acceptor strength of the cation.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1467–1473, July, 1990.     

Complexes of metal ions with phosphorus or arsenic containing ligands,part XX. Chelates ofo-phenylenebis(diarylarsines) with palladium(II) and platinum(II) halides,pseudohalides and perchlorates

Summary Two ditertiaryarsines,o-phenylenebis(diphenylarsine), (pdpa) ando-phenylenebis(di-p-tolylarsine), (pdta) yield some new complexes of palladium(II) and platinum(II). These are: square planar M(pdta)X₂ · nCH₂Cl₂, [M = Pd, X = Cl, Br or NCS; M = Pt, X = Cl]; [Pt(A-A)₂] X₂ · nCH₂Cl₂, [(A-A) = pdta, X = Cl, NCS or ClO₄; (A-A) = pdpa, X=ClO₄] and [M₂(A-A)₂(NCS)₂] (ClO₄)₂ · nCH₂Cl₂, [M = Pd, (A-A) = pdta; M = Pt, (A-A) = pdpa]; distorted octahedral M(pdta)₂-X₂nCH₂Cl₂, [M = Pd, X = I; M = Pt, X = Br or I] and [Pd(pdta)₂(H₂O)₂](ClO₄)₂, and five coordinate [M(A-A)₂X] ClO₄ · nCH₂Cl₂, [M = Pd, Pt, (A-A) = pdta, X = I; M = Pt, (A-A) = pdpa, X = Br or I]. The [M₂(A-A)₂(NCS)₂] (ClO₄)₂ · nCH₂Cl₂ complexes are novel in the sense that they contain bridging thiocyanate together with ionic perchlorate. The stereochemical assignments have been made on the basis of i.r. and u.v. spectra as well as conductance data.     

FTIR study of ion solvation and ion-pair formation in alkaline and alkaline earth metal salt solutions in acetonitrile

The IR spectra of alkaline and alkaline earth metal perchlorate and of lithium bromide solutions in acetonitrile, obtained with the help of FTIR measurements in the region of the C-N stretching mode of the solvent, reveal bands produced by acetonitrile molecules in the solvation shells and bands of ClO ₄ ^– ions in contact and solvent separated ion pairs. The shift and the attenuation of the C-N stretching band of acetonitrile at 2254 cm^–1 is used for the calculation of cation solvation numbers for Li⁺(4), Na⁺(4), Mg²⁺(6), Ca²⁺(6), and Ba²⁺(6). No solvation is assumed for the contact ion pairs of LiClO₄, LiBr, NaClO₄, Mg(ClO₄)₂, Ca(ClO₄)₂, and Ba(ClO₄)₂. The association constants of the symmetrical electrolytes are compared to those obtained from other methods.     

Mobilities of complex forming cations in non-aqueous donor solvents

Conductance measurements are reported for Al(ClO₄)₃ in acetonitrile Co(ClO₄)₂, Zn(ClO₄)₂, and Al(ClO₄)₃ in dimethylformamide, and Al(ClO₄)₃, Fe(ClO₄)₃, and FeCl₃ in dimethylsulfoxide (DMSO), at 25°C. From uv spectral effects the FeCl (DMSO) ₅ ²⁺ complex cation is shown, to predominate in DMSO, while hexasolvated cations occur in the metal perchlorate solutions. The limiting conductances of the cations, including earlier data, indicate non-Stokesian dependences of mobility on the ionic charge, a unique property of the structurally related complex ions ML ₆ ^z+ and MXL ₅ ^(z–1)+ . The observed regularities are discussed in terms of both their possible applications and the migration mechanism.     

Thorium(IV) and zirconium(IV) complexes of oxygen donor ligands,Part 6. thorium(IV) complexes of 2,6-lutidine-N-oxide and tetramethylene sulphoxide

Summary The synthesis and physical properties of crystalline thorium(IV) complexes, Th(ClO₄)₄ · 6 LNO, ThX₄ · 2 LNO (X = Br or SCN), ThX₄ · 4 LNO (X = NO₃ or I) andTh(ClO₄)₄ · 10 TMSO, Th(NO₃)₄ · 6 TMSO, ThX₄ · 4 TMSO (X = Cl or Br), ThI₄ · 6 TMSO and Th(NCS)₄ · 2 TMSO (where LNO = 2,6-lutidine-N-oxide and TMSO = tetramethylene sulphoxide) are reported together with their i.r. spectra, molar conductivities, molecular weights, t. g. a. and d. t. a. data. In all the complexes, LNO and TMSO are bonded to thorium(IV) through oxygen. The coordination number of thorium(IV) in these complexes varies from six to ten depending upon the nature of the anions.Presented at the XVI Annual Convention of Chemists, Andhra University, Waltair, A. P. India, December 27–31, 1978.     

Water-vapor pressure and thermodynamics of the dehydration of manganese,nickel, cadmium,and lead perchlorate hydrates

The water-vapor pressure has been measured by a static method, the temperature limits for existence have been determined, and the parameters of the equation lgp [Torr]=b —a/T have been calculated for the following crystal hydrates: Mn(ClO₄)₂ · 2H₂O (90–130°C, a=3527.0,b=8.487), Ni(ClO₄)₂ · 4H₂O (60–100°C,a=3606.7,b=9.704), Ni(C1O₄)₂ · 2H₂O (110–160°C,a = 4261.7,b = 10.103), Cd(ClO₄)₂ · 6H₂O (25–58.2°C,a = 3143.7,b = 9.356), Cd(ClO₄)₂ · 2H₂O (90–144.8°C,a=3823.3,b = 9.472), Pb(ClO₄)₂ · 3H₂O (10–47°C,a = 2932.9,b = 9.391 and 47–81.5°C,a = 2448.1,b=7.877), Pb(ClO₄)₂ · H₂O (60–102.4°C,a=3610.2,b = 9.857). A hitherto unknown metastable hydrate Cd(ClO₄)₂ · 4H₂O with a phase transition at 30.9°C (20–30.9°C,a = 3669.5,b = 11.343 and 30.9–63.7°C,a=3058.6,b = 9.339) has been detected.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 466–470, March, 1993.     

Calorimetric study and thermal analysis of [Gd4/3Y2/3(Gly)6(H2O)4](ClO4)6·5H2O and [ErY(Gly)6(H2O)4](ClO4)6·5H2O (Gly: glycin)

Two solid-state coordination compounds of rare earth metals with glycin, [Gd_4/3Y_2/3(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O and [ErY(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O were synthesized. The low-temperature heat capacities of the two coordination compounds were measured with an adiabatic calorimeter over the temperature range from 78 to 376 K. [Gd_4/3Y_2/3(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O melted at 342.90 K, while [ErY(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O melted at 328.79 K. The molar enthalpy and entropy of fusion for the two coordination compounds were determined to be 18.48 kJ mol⁻¹ and 53.9 J K⁻¹ mol⁻¹ for [Gd_4/3Y_2/3(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O, 1.82 kJ mol⁻¹ and 5.5 J K⁻¹ mol⁻¹ for [ErY(Gly)₆(H₂O)₄](ClO₄)₆·5H₂O, respectively. Thermal decompositions of the two coordination compounds were studied through the thermogravimetry (TG). Possible mechanisms of the decompositions are discussed.     

Apparent molar heat capacities and volumes of aqueous electrolytes: CaCl2, Cd(NO3)2, CoCl2, Cu(ClO4)2, Mg(ClO4)2, and NiCl2

We have used a flow calorimeter and a flow densimeter for measurements leading to apparent molar heat capacities and apparent molar volumes of six 21 electrolytes in aqueous solution at 25°C. Results of these measurements have been used to derive apparent molar heat capacities and volumes at infinite dilution for all six electrolytes: CaCl₂, Cd(NO₃)₂, CoCl₂, Cu(ClO₄)₂, Mg(ClO₄)₂, and NiCl₂.     

Extraktion der Seltenen Erden mit Tributylphosphat aus einer Nitrat-Perchlorat-Lösung

Zusammenfassung Bei der Extraktion von Pr und Yb mitTBP aus Nitrat-Perchlorat-Lösung (Ionenstärke 3,5m, konstante Konzentration des Extraktionsmittels) bilden sich in der organischen Phase-außer den einfachen Tri- und Hexasolvaten-auch gemischte Nitrat-Perchlorat-Solvate folgender Zusammensetzung:Ln(NO₃)₂(ClO₄) · 3TBP;Ln(NO₃)(ClO₄)₂ · 3TBP;Ln(NO₃)-(ClO₄)₂ · 6TBP;Ln(NO₃)₂(ClO₄) · 6TBP. Die Aktivitätskoeffizienten der extrahierten Salze bleiben bei konstanter Ionenstärke unverändert, unabhängig von der Änderung des Verhältnisses ihrer Anionen.

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Extraction of rare earths with tributyl phosphate from a nitrate-perchlorate medium

The extraction of Pr and Yb withTBP from a nitrate-perchlorate medium at an ionic strength of 3.5m and constant concentration of the extraction agent has been investigated. It was found that in the organic phase, besides the simple tri-and hexa-solvates, the mixed nitrate-perchlorate solvates of the following compositions are also formed:Ln(NO₃)₂(ClO₄) · 3TBP;Ln(NO₃)(ClO₄)₂ · 3TBP;Ln(NO₃) · (ClO₄)₂ · 6TBP;Ln(NO₃)₂(ClO₄) · 6TBP. The activity coefficients of the extracted salts, at a constant ionic strength remain unchanged, irrespective of the change of ratio between their anions.

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Mit 3 Abbildungen     

Supramolecular architectures constructed by lanthanum, amino acids and 1,10-phenanthroline via non-covalent bond interactions

Three supramolecular lanthanum coordination compounds of amino acids, with 1,10-phenanthroline (phen), [La₂(APA)₆(phen)₂(H₂O)₂](ClO₄)₆(phen)₄·2H₂O (1), [La₂(ABA)₆(phen)₂(H₂O)₂](ClO₄)₆ (phen)₆·4H₂O (2), and [La₂(AHA)₄(phen)₄](ClO₄)₆(phen)₄·2H₂O (3) (APA=3-aminopropionic acid; ABA=4-aminobutanoic acid; AHA=6-aminohexanoic acid) were synthesized and characterized by single crystal X-ray diffraction. The results show that the three coordination compounds are all composed of binuclear coordination cations built by metal-ligand coordination. Through hydrogen bonding and π-π stacking interactions, complex 1 forms a two-dimensional supramolecular sheet structure extending in the (001) plane, complex 2 forms a three-dimensional supramolecular network with many cavities occupied by ClO₄⁻ and lattice H₂O molecules, and complex 3 forms a two-dimensional supramolecular lamellar structure in the (100) plane.     

Temperature Dependence of Ligand Exchange in the Coordination Sphere of Tb(ClO4)3 · nH2O in the Presence of Adamantylideneadamantane-1,2-dioxetane and Benzophenone in Acetonitrile Solutions

The processes of complexation and solvation in the Tb(ClO₄)₃ · nH₂O –adamantylideneadamantane-1,2-dioxetane (I)–benzophenone (II) system in acetonitrile solutions were studied at 280–320 K. The complexation of Tb(ClO₄)₃ · nH₂O in ground and electronically excited states with I and II was found out. An anomalous increase in the lifetime of Tb(ClO₄)^* ₃ · nH₂O with temperature was observed; this anomalous increase is indicative of a structural change in the environment of the terbium ion in solution. It was found that of Tb(III)* increased because of rearrangement of the inner sphere of solvation aqua complexes toward the replacement of H₂O molecules by solvent molecules that exhibit a lower quenching ability.     

Solution and solvation thermochemistry of copper(II) and nickel(II) nitrates in water and acetonitrile mixtures at 298 K

The calorimetric enthalpies of mixing of aqueous solutions of Cu(NO₃)₂ and Ni(NO₃)₂ in mixtures of water with acetonitrile (AN) at 298 K are measured over the entire range of the compositions. The ionic enthalpies of transfer from pure water to water mixed with AN are calculated. The behavioral features of d cations, as distinct from simple ions, are recognized. The contributions from the universal, chemical, and electrostatic interactions between the ion and solvent to the enthalpy of ion transfer are calculated. The structural term of the enthalpy of ion transfer that reflects the energy (enthalpy) changes in the solution induced by the chemical interaction of an ion with the solvent is obtained; the regions of d-cation resolvation in the solution are recognized as a result.     

Metal complexes of phytohormones. Part II. Copper(II) complexes of 6-benzylaminopurine

Summary Copper(II) complexes with 6-benzylaminopurine (BAPH) of the types Cu(BAPH)₂(ClO₄)₂·2H₂O (1) Cu(BAP)₂·4H₂O (2), and Cu(BAPH₂)Cl₃·MeOH (3), have been synthesized and characterized by conductivity, magnetic measurements, i.r., electronic and e.s.r. spectroscopy.     

Transition metal Complexes with Bis(2′-quinolyl)-2,6-pyridine

Studies on the complexes of transition metals with the tridentate imine ligand bis(2′-quinolyl)-2, 6-pyridine have been carried out. On the basis of the elemental analysis data and the molar electrical conductivities, the chelates have been assigned the general formula [Me(C₂₃H₁₅N₃)₂](ClO₄)₂, where Me was Fe(II), Co(II), Mn(II), Cu(II) and Ni(II). Their electronic spectra in the solid state and in acetonitrile solution, as well as their infrared spectra have been reported and discussed.     

Apparent molar heat capacities and volumes of aqueous electrolytes at 25°C: Cd(ClO4)2, Ca(ClO4)2, Co(ClO4)2, Mn(ClO4)2, Ni(ClO4)2, and Zn(ClO4)2

We have used a flow calorimeter and a flow densimeter for measurements leading to apparent molar heat capacities and apparent molar volumes of aqueous solutions of Cd(ClO₄)₂, Ca(ClO₄)₂, Co(ClO₄)₂, Mn(ClO₄)₂, Ni(ClO₄)₂, and Zn(ClO₄)₂. The resulting apparent molar quantities have been extrapolated to infinite dilution to obtain the corresponding standardstate apparent and partial molar heat capacities and volumes. These latter values have been used for calculation of conventional ionic heat capacities and volumes.     

Pendant-Arm Macrocycles Derived from the Cyclocondensation Reaction of Sodium 2,6-Diformyl-4-substitutedphenolates and Tris-(2-aminoethyl)amine Derivatives. Preparation, Characterization and Properties of their Dinuclear Copper(II) Complexes

A series of pendant-arm Schiff base macrocycles have been obtained via the cyclocondensation reaction between sodium 2,6-diformyl-4-substitutedphenolates and tris-(2-aminoethyl)- amine derivatives followed by transmetallation with Cu(ClO₄)₂·6H₂O. The resulting dinuclear copper(II) complexes have been characterized by elemental analysis, infrared and mass spectra as well as magnetic moments at room temperature. All complexes have been electrochemically investigated, and two typical compounds have been studied with ESR spectra as well.