The volume change for the dissociation of telluric acid

The hydrolysis constants of telluric acid were determined by potentiometric titrations at 25°C andI=1.0 mol kg^–1 NaClO₄. Using these results the partial molar volume change according to the dissociation reaction Te(OH)_6(aq) TeO(OH) _5(aq) ^– +H _(aq) ⁺ was measured densitymetrically.

---

Das Dissoziationsvolumen der Tellursäure (Kurze Mitteilung)

Zusammenfassung Die Hydrolysekonstanten der Tellursäure wurden bei 25°C undI=1.0 mol kg^–1 NaClO₄ durch potentiometrische Titrationen bestimmt. Diese Ergebnisse wurden verwendet, um die Volumsänderung zufolge der Dissoziationsreaktion Te(OH)_6(aq) TeO(OH) _5(aq) ^– +H _(aq) ⁺ durch Dichtemessungen zu ermitteln.

     

Cerium(IV) Hexanuclear Clusters from Cerium(III) Precursors: Molecular Models for Oxidative Growth of Ceria Nanoparticles

Reactions of cerium(III) nitrate, Ce(NO₃)₃?6 H₂O, with different carboxylic acids, such as pivalic acid, benzoic acid, and 4‐methoxybenzoic acid, in the presence of a tridentate N,N,N‐donor ligand, diethylenetriamine (L¹), under aerobic conditions yielded the corresponding cerium hexamers Ce₆O₈(O₂CtBu)₈(L¹)₄ ( 1 ), Ce₆O₈(O₂CC₆H₅)₈(L¹)₄ ( 2 ), and Ce₆O₈(O₂CC₆H₄‐4‐OCH₃)₈(L¹)₄ ( 3 ). Hexamers 1 , 2 , and 3 contain the same octahedral Ce^IV₆O₈ core, in which all interstitial oxygen atoms are connected by μ₃‐oxo bridging ligands. In contrast, treatment of the Ce^IV precursor (NH₄)₂Ce(NO₃)₆ (CAN) with pivalic acid and the ligand L¹ under the same conditions afforded Ce₆O₄(OH)₄(O₂CtBu)₁₂(L¹)₂ ( 4 ), exhibiting a deformed octahedral Ce^IV₆O₄(OH)₄ core containing μ₃‐oxo and μ₃‐hydroxo moieties in defined positions. In contrast to the formation of 1 – 3 , the use of N‐methyldiethanolamine (L) in the reaction with Ce(NO₃)₃?6 H₂O and pivalic acid afforded a previously reported Ce^III dinuclear cluster, Ce₂(O₂CtBu)₆L₂, even in the presence of dioxygen. ESI‐MS analysis of the reaction mixture clearly indicated the importance of the ligand L¹ in promoting oxidation of the Ce^III aggregates, [Ce_n(O₂CtBu)_3n(L¹)₂], which is necessary for the formation of Ce^IV hexamers.     

Rate constants for the reaction of hydrated electrons and hydroxyl radicals with acrylate monomers

The hydrated electron (e⁻_aq) and hydroxyl radical rate constants with 18 acrylate-, methacrylate-, crotonate-, fumarate- and maleate esters are discussed. The constants approach the diffusion-controlled limit. k(e⁻_aq) and k(OH) change in opposite direction; if k(e⁻_aq) is high then k(OH) is small. This tendency is connected with the nucleophilic character of e⁻_aq and the electrophilic character of OH, although the site of attack of e⁻_aq and OH is different: carbonyl versus vinyl group.     

Homo‐ and Heterovalent Polynuclear Cerium and Cerium/Manganese Aggregates

Reactions of Ce^III(NO₃)₃?6 H₂O or (NH₄)₂[Ce^IV(NO₃)₆] with Mn‐containing starting materials result in seven novel polynuclear Ce or Ce/Mn complexes with pivalato (^tBuCO ) and, in most cases, auxiliary N,O‐ or N,O,O‐donor ligands. With nuclearities ranging from 6–14, the compounds present aesthetically pleasing structures. Complexes [Ce^IV₆(μ₃‐O)₄(μ₃‐OH)₄(μ‐O₂C^tBu)₁₂] ( 1 ), [Ce^IV₆Mn^III₄(μ₄‐O)₄(μ₃‐O)₄(O₂C^tBu)₁₂(ea)₄(OAc)₄]?4 H₂O?4 MeCN (ea^?=2‐aminoethanolato; 2 ), [Ce^IV₆Mn^III₈(μ₄‐O)₄(μ₃‐O)₈(pye)₄(O₂C^tBu)₁₈]₂[Ce^IV₆(μ₃‐O)₄(μ₃‐OH)₄(O₂C^tBu)₁₀(NO₃)₄] [Ce^III(NO₃)₅(H₂O)]?21 MeCN (pye^?=pyridine‐2‐ethanolato; 3 ), and [Ce^IV₆Ce^III₂Mn^III₂(μ₄‐O)₄(μ₃‐O)₄(^tbdea)₂(O₂C^tBu)₁₂(NO₃)₂(OAc)₂]?4 CH₂Cl₂ (^tbdea^2?=2,2′‐(tert‐butylimino]bis[ethanolato]; 4 ) all contain structures based on an octahedral {Ce^IV₆(μ₃‐O)₈} core, in which many of the O‐atoms are either protonated to give (μ₃‐OH)^? hydroxo ligands or coordinate to further metal centers (Mn^III or Ce^III) to give interstitial (μ₄‐O)^2? oxo bridges. The decanuclear complex [Ce^IV₈Ce^IIIMn^III(μ₄‐O)₃(μ₃‐O)₃(μ₃‐OH)₂(μ‐OH)(bdea)₄(O₂C^tBu)_9.5(NO₃)_3.5(OAc)₂]?1.5 MeCN (bdea^2?=2,2′‐(butylimino]bis[ethanolato]; 5 ) contains a rather compact Ce^IV₇ core with the Ce^III and Mn^III centers well‐separated from each other on the periphery. The aggregate in [Ce^IV₄Mn^IV₂(μ₃‐O)₄(bdea)₂(O₂C^tBu)₁₀(NO₃)₂]?4 MeCN ( 6 ) is based on a quasi‐planar {Mn^IV₂Ce^IV₄(μ₃‐O)₄} core made up of four edge‐sharing {Mn^IVCe^IV₂(μ₃‐O)} or {Ce^IV₃(μ₃‐O)} triangles. The structure of [Ce^IV₃Mn^IV₄Mn^III(μ₄‐O)₂(μ₃‐O)₇(O₂C^tBu)₁₂(NO₃)(furan)]?6 H₂O ( 7 ?6 H₂O) can be considered as {Mn^IV₂Ce^IV₂O₄} and distorted {Mn^IV₂Mn^IIICe^IVO₄} cubane units linked through a central (μ₄‐O) bridge. The Ce₆Mn₈ equals the highest nuclearity yet reported for a heterometallic Ce/Mn aggregate. In contrast to most of the previously reported heterometallic Ce/Mn systems, which contain only Ce^IV and either Mn^IV or Mn^III, some of the aggregates presented here show mixed valency, either Mn^IV/Mn^III (see 7 ) or Ce^IV/Ce^III (see 4 and 5 ). Interestingly, some of the compounds, including the heterovalent Ce^IV/Ce^III 4 , could be obtained from either Ce^III(NO₃)₃?6 H₂O or (NH₄)₂[Ce^IV(NO₃)₆] as starting material.     

Bright Photoluminescence of [{(Cp )2Ce(μ‐Cl)}2]: A Valuable Technique for the Determination of the Oxidation State of Cerium

The synthesis and photoluminescence properties of the bright‐yellow organocerium complex [{(Cp )₂Ce(μ‐Cl)}₂] (Cp =1,3‐di(tert‐butyl)cyclopentadienyl) are presented. This coordination compound exhibits highly efficient photoluminescence within the yellow‐light wavelength range, with a high internal quantum yield of 61(±2) % at room temperature. The large red shift is attributed to the delocalizing ability of the aromatic ligands, whilst its quantum yield even makes this compound competitive with Ce³⁺‐activated LED phosphors in terms of its photoluminescence efficiency (disregarding its thermal stability). A bridging connection between two crystallographically independent Ce³⁺ ions is anticipated to be the reason for the highly efficient photoluminescence, even up to room temperature. The emission spectrum is characterized by two bands in the orange‐light range at both 10 K and room temperature, which are attributed to the parity‐allowed transitions 5d¹(²D_3/2)→4f¹(²F_7/2) and 5d¹(²D_3/2)→4f¹(²F_5/2) of Ce³⁺, respectively. The photoluminescence spectra were interpreted in relation to the structure and vibrational modes of the coordination compound. The spectra and optical properties indicate that trivalent cerium ions are the dominant species in the ground state, which also resolves an often‐encountered ambiguity in organocerium compounds. This result shows that photoluminescence spectroscopy is a versatile tool that can help elucidate the oxidation state of Ce in such compounds.     

The standard molar enthalpy of formation of Ce2(MoO4)3(s) and Sm2(MoO4)3(s) using solution calorimetry

The enthalpies of formations of Ce₂(MoO₄)₃(s) and Sm₂(MoO₄)₃(s) have been measured at 298.15 K using semi adiabatic solution calorimetry. The precipitation reaction between RE(NO₃)₃·6H₂O(s) (R= Ce, Sm) and ammonical solution of Na₂MoO₄(s) was studied. From the enthalpy of precipitation and other required auxiliary data, $ \Updelta_{\text{f}} H_{\text{m}}^{ \circ } \left( { 2 9 8. 1 5 {\text{ K}}} \right) $ Δ f H m ° ( 2 9 8.1 5 K ) of Ce₂(MoO₄)₃(s) and Sm₂(MoO₄)₃(s) have been calculated for the first time as ?4388.7 ± 3.6 and ?4363.4 ± 4.1 kJ mol^?1, respectively. The enthalpy of hydration of anhydrous Ce(NO₃)₃(s) to Ce(NO₃)₃·6H₂O(s) has been calculated. $ \Updelta_{\text{f}} H_{\text{m}}^{ \circ } \left( {{\text{MoO4}}^{ 2- } ,\,{\text{aq}},\, 2 9 8. 1 5 \,{\text{K}}} \right) $ Δ f H m ° ( MoO4 2 ? , aq , 2 9 8.1 5 K ) has also been measured and calculated as ?995.1 kJ mol^?1 from required literature data.     

Reactions of ortho-Phenylenediamine with a Nickel Trimethylacetate Complex

Interaction of ortho-phenylenediamine with the nonanuclear nickel trimethylacetate cluster Ni₉(₄-OH)₃(₃-OH)₃( _n -OOCMe₃)₁₂(HOOCCMe₃)₄(I) in an amine deficiency yields the antiferromagnetic trinuclear complex [Ni₃{-N,N"-(NH₂)₂C₆H₄}₂(HCCOOCMe₃)₃(₃-OH)(-OOCCMe₃)₄]⁺(OOCCMe₃)^–(III) containing bridging diamine ligands. Reaction of excess diamine with Ior IIIleads to the formation of the paramagnetic monomer Ni{²-o-(NH₂)₂C₆H₄}₂(OOCCMe₃)₂(IV), which reacts with atmospheric oxygen to form the known bis(semiquinonediimine) complex Ni[1,2-(NH)₂C₆H₄]₂(V).     

Synthesis and Structure of [Pd(NH3)4][cis-Pd(NH3)2(SO3)2][Pd(NH3)3(SO3)] · H2O

A new palladium compound [Pd(NH₃)₄][cis-Pd(NH₃)₂(SO₃)₂][Pd(NH₃)₃(SO₃)] · H₂O (I) was synthesized and its structure was studied by X-ray powder diffraction method. In the course of the synthesis, the initial trans-diamminesulfite anionic complex is transformed into the cis-configuration. Further heating in aqueous solution results in isomerization of a substance into a neutral complex [Pd(NH₃)₃(SO₃)]. Crystals I are triclinic: a = 10.3297(2) Å, b = 14.1062(3) Å, c = 6.8531(1) Å, = 101.36(0)°, = 92.74(0)°, = 92.71(0)°, space group P1¯. Structure I consists of the columns with alternating cis-[Pd(NH₃)₂(SO₃)₂]^2– and [Pd(NH₃)₃(SO₃)] complexes and [Pd(NH₃)₄]²⁺ ions between the columns.     

A Novel Self‐assembled Nickel(II)‐Cerium(III) Heterotetranuclear Dimer Constructed from N2O2‐type Bisoxime and Terephthalic Acid: Synthesis,Structure, and Photophysical Properties

By self‐assembly of a Salamo‐type ligand H₂L [H₂L = 1,2‐bis(3‐methoxysalicylideneaminooxy)ethane] with Ni(OAc)₂ · 4H₂O, Ce(NO₃)₃ · 6H₂O, and H₂bdc (H₂bdc = terephthalic acid), a novel Ni^II‐Ce^III heterometallic complex, [{Ni(L)Ce(NO₃)₂(CH₃OH)(DMF)}₂(bdc)], was obtained. Two crystallographically equivalent [Ni(L)Ce(NO₃)₂(CH₃OH)(DMF)] moieties lie in the inversion center, and are linked by one bdc^2– ligand leading to a heterotetranuclear dimer, in which the carboxylato group bridges the Ni^II and Ce^III atoms. Moreover, the photophysical properties of the Ni^II‐Ce^III complex were studied.     

Copper(II) Complexes with Ethyl [(Pyrazolo-1-carbothioyl)-amino]acetate Derivatives: Synthesis and Structure

Optically active derivative of the natural monoterpene (+)-3-carene, namely, ethyl (3bS,4aR)-[(3,4,4-trimethyl-3b,4,4a,5-tetrahydrocyclopropa[3,4]cyclopenta[1,2-c]pyrazole-1-carbothioyl)-amino]acetate (HL¹) and ethyl [(3,5-dimethyl-pyrazole-1-carbothioyl)-amino]acetate (HL²) were synthesized. Paramagnetic complexes [CuL¹Cl] _n (I) and [Cu₂L² ₂Cl₂] (II) were prepared. According to X-ray diffraction data, complex Iwith anion of (+)-3-carene derivative has chain structure, whereas complex IIwith anion of HL², which has no carbocyclic fragments, is a pseudodimer. Organic anions act as tetradentate bridging, cyclic ligands forming five-membered CuN₃C and CuNOC₂metal cycles. Coordination polyhedron of Cu(ClN₂O + S) in complexes Iand IIis a square pyramid. The values of _efffor complexes Iand II(1.88 and 1.84 _B, respectively) are constant in the temperature interval 78–300 K, which means that the unpaired electrons of Cu(II) ions do not exhibit any noticeable exchange interactions.     

Chemie der Seltenerdmetalle, 7. Mitt.: Tartratkomplexe des dreiwertigen Cers

Zusammenfassung Es wurde die systematische Untersuchung des Systems im sauren Bereich durchgeführt. Es wurden Stoffe der Zusammensetzung Ce₂(H₂ T)₃·6H₂O, Ce₂(H₂ T)₃·2H₂O, H[Ce(H₂ T)₂]·2H₂O isoliert^***. Diese wurden röntgenographisch untersucht und es wurde ihre thermische Analyse durchgeführt. Auf Grund von pH-Messungen wurden die Dissoziationskonstanten bestimmt.

---

The systems were investigated in the acidic range. The compounds Ce₂(H₂ T)₃·6 H₂O, Ce₂(H₂ T)₃·2 H₂O and H[Ce(H₂ T)₂]·2 H₂O^*** were isolated. X-ray powder diagrams were taken, and a thermal analysis performed. The dissociation constants were determined, based upon pH-measurements.

---

---

Mit 2 Abbildungen

---

6. Mitt.:F. Bezina, J. Rosický undR. Pastorek, Acta Univ. Palack., im Druck.     

Electronic structure,magnetic properties,and mixed valence character of Ce2Ni3Si5 from first principles calculations

Cerium intermetallic compounds exhibit anomalous physical properties such as heavy fermion and Kondo behaviors. Here, an ab initio study of the electronic structure, magnetic properties, and mixed valence character of Ce₂Ni₃Si₅ using density functional theory (DFT) is presented. Two theoretical methods, including pure Perdew–Burke–Ernzerhof (PBE) and PBE + U , are used. In this study, Ce³⁺ and Ce⁴⁺ are considered as two different constituents in the unit cell. The formation energy calculations on the DFT level propose that Ce is in a stable mixed valence of 3.379 at 0 K. The calculated electronic structure shows that Ce₂Ni₃Si₅ is a metallic compound with a contribution at the Fermi level from Ce 4f and Ni 3d states. With the inclusion of the effective Hubbard parameter (U _eff), the five valence electrons of 5 Ce³⁺ ions are distributed only on Ce³⁺ 4f orbitals. Therefore, the occupied Ce³⁺ 4f band is located in the valence band (VB) while Ce⁴⁺ 4f orbitals are empty and Located at the Fermi level. The calculated magnetic moment in Ce₂Ni₃Si₅ is only due to cerium (Ce³⁺) in good agreement with the experimental results. The U _eff value of 5.4 eV provides a reasonable magnetic moment of 0.981 for the unpaired electron per Ce³⁺ ion. These results may serve as a guide for studying present mixed valence cerium‐based compounds. © 2017 Wiley Periodicals, Inc.     

Interaction of bivalent transition metal ions with iminodiacetato-(pentaammine/tetraammine)cobalt(III) ions. A kinetic and equilibrium study

Summary The kinetics of reversible complexation of Ni^II and Co^II with iminodiacetato(pentaammine)cobalt(III), [(NH₃)₅-Co(idaH₂)]³⁺ and Ni^II with iminodiacetato(tetraammine)-cobalt(III), [(NH₃)₄Co(idaH)]²⁺, have been investigated by the stopped-flow technique at 25 °C, pH = 5.7–6.9 and I = 0.3 mol dm ^–3. The reaction paths (NH₃)₅Co(idaH)²⁺+M²⁺(NH₃)₅Co(ida)M³⁺+H⁺ (NH₃)₅Co(ida)⁺+M²⁺(NH₃)₅Co(ida)M³⁺ (NH₃)₄Co(ida)⁺+Ni²⁺(NH₃)₄Co(ida)Ni³⁺ have been identified (idaH = N⁺H₂(CH₂CO₂)₂H, ida = NH(CH₂COO)^2–]. The rate parameters for the formation and dissociation of the binuclear species are reported. The data are essentially consistent with an I _d mechanism. The dissociation rate constants of the binuclear species indicate that Ni²⁺ and Co²⁺ are chelated by the coordinated iminodiacetate moiety.     

Cerium(III) Complexes with Lacunary Polyoxotungstates. Synthesis and Structural Characterization of a Novel Heteropolyoxotungstate Based on α-[SbW9O33]9− Units

Several cerium(III) complexes with lacunary polyoxotungstates -B-XW₉O^9– ₃₃ (X=As^III, Sb^III) and W₅O^6– ₁₈, have been synthesized and characterized by single-crystal X-ray analysis, elemental analysis and IR spectroscopy. The X-ray analysis of Na₂₅[Ce(H₂O)₅As₄W₄₀O₁₄₀]63H₂O (1) reveals the framework of the well-known [As₄W₄₀O₁₄₀]^28– anion with a {Ce(H₂O)₅}³⁺ unit in the central site S1. The anion in (NH₄)₁₉[(SbW₉O₃₃)₄{WO₂(H₂O)}₂Ce₃(H₂O)₈(Sb₄O₄)]48H₂O (2) consists of a tetrahedral assembly of four -B-Sb^IIIW₉O^9– ₃₃ units connected by two additional six-coordinate tungsten atoms, three nine-coordinate monocapped square-antiprismatic cerium atoms and a Sb₄O₄ cluster. The Ce^III center in the [Ce(W₅O₁₈)₂]^9– anion in Na₉[Ce(W₅O₁₈)]NaCl30H₂O (3) displays the square-antiprismatic environment observed in all complexes of the type [Ln(W₅O₁₈)₂] ^n–.     

Spectroscopic,electrochemical, and structural aspects of the Ce(IV)/Ce(III) DOTA redox couple chemistry in aqueous solutions

The redox potential of the Ce(IV)/Ce(III) DOTA is determined to be 0.65 V versus SCE, pointing out a stabilization of ~13 orders of magnitude for the Ce(IV)DOTA complex, as compared to Ce(IV)_aq. The Ce(III)DOTA after electrochemical oxidation yields a Ce(IV)DOTA complex with a t_1/2 ~3 h and which is suggested to retain the “in cage” geometry. Chemical oxidation of Ce(III)DOTA by diperoxosulfate renders a similar Ce(IV)DOTA complex with the same t_1/2. From the electrochemical measurements, one calculates logK (Ce(IV)DOTA^2?) ~ 35.9. Surprisingly, when Ce(IV)DOTA is obtained by mixing Ce(IV)_aq with DOTA, a different species is obtained with a 2 : 1(M : L) stoichiometry. This new complex, Ce(IV)DOTACe(IV), shows redox and spectroscopic features which are different from the electrochemically prepared Ce(IV)DOTA. When one uses thiosulfate as a reducing agent of Ce(IV)DOTACe(IV), one gets a prolonged lifetime of the latter. The reductant seems to serve primarily as a coordinating ligand with a geometry which does not facilitate inner sphere electron transfer. The reduction process rate in this case could be dictated by an outer sphere electron transfer or DOTA exchange by S₂O₃^2?. Both Ce(IV)DOTA and Ce(IV)DOTACe(IV) have similar kinetic stability and presumably decompose via decarboxylation of the polyaminocarboxylate ligand.     

Two Regioisomers of Endohedral Pyrrolidinodimetallofullerenes M2@Ih‐C80(CH2)2NTrt (M=La,Ce; Trt=trityl): Control of Metal Atom Positions by Addition Positions

The two regioisomers of endohedral pyrrolidinodimetallofullerenes M₂@I_h‐C₈₀(CH₂)₂NTrt (M=La, Ce; Trt=trityl) were synthesized, isolated, and characterized. X‐ray crystallographic analyses of [6,6]‐La₂@I_h‐C₈₀(CH₂)₂NTrt and [6,6]‐Ce₂@I_h‐C₈₀(CH₂)₂NTrt revealed that the encapsulated metal atoms are located at the slantwise positions on the mirror plane that parallels the pyrrolidine ring. Paramagnetic NMR analyses of [6,6]‐ and [5,6]‐Ce₂@I_h‐C₈₀(CH₂)₂NTrt were also carried out to clarify the metal positions. As for the [6,6]‐adduct, the metal positions obtained by paramagnetic NMR analysis agree well with the X‐ray structure. In contrast, paramagnetic NMR analysis of the [5,6]‐adduct showed that the two Ce atoms are collinear with the pyrrolidine ring. We also compared the observed paramagnetic effects of the pyrrolidinodimetallofullerenes with those of other cerium‐encapsulating fullerene derivatives such as bis‐silylated Ce₂@I_h‐C₈₀ and a carbene adduct of Ce₂@I_h‐C₈₀. We found that the metal positions can be explained by the electrostatic potential maps of the corresponding [6,6]‐ and [5,6]‐adducts of [I_h‐C₈₀(CH₂)₂NTrt]^6?. These findings clearly show that metal positions inside fullerene cages can be controlled by means of the addition positions of the addends. In addition, the radical anions of the pyrrolidinodimetallofullerenes were prepared by bulk controlled‐potential electrolysis and characterized by X‐band EPR spectral study.     

Complex formation between nickel(II) and 2-(2-aminoethyl) benzimidazole: A kinetic and equilibrium study

Summary The reversible complex formation between 2-(2-aminoethyl) benzimidazole (AEB) and nickel(II) was studied by stopped flow spectrophotometry at I = 0.30 mol dm^–3. Both the neutral and monoprotonated form of AEB reacted to give the NiAEB²⁺ chelate. At 25 °C, the rates and activation parameters for the reactions Ni_II + AEB NiAEB²⁺ and Ni^II + AEBH⁺ NiAEB²⁺ + H⁺ are k _f ^L(dm^–3 mol^–1 s^–1) = (2.17 ± 0.24) × 10³, H (kJ mol^–1) = 40.0 ± 0.8, S (JK^–1 mol^–1) = – 47 ± 3 and k _inff ^pHL (dm³ mol^–1 s^–1) = 33 ± 10, H (kJ mol^–1) = 42.0 ±2.7, S (JK^–1 mol^–1) = – 72 ± 9. The dissociation of NiAEB²⁺ was acid catalysed and k _obs for this process increased linearly with [H⁺] in the 0.01–0.15 mol dm^–3 (10–30 °C) range with k _H(dm³ mol^–1s^–1) (25 °C) = 329 ± 6, H (kJ mol^–1) = 40 ± 2 and S (JK^–1 mol^–1) = – 61 ± 8. The results also indicated that the formation of NiAEB²⁺ involves a chelation-controlled, rate-limiting process. Analysis of the S ° data for the acid ionisation of AEBH _inf2 ^p2+ and the formation of NiAEB²⁺ showed that the bulky AEBH⁺ ion has a solvent structure breaking effect as compared to AEB [s _aqS ° (AEBH⁺) – s _aq ° (AEB) = 69 JK^–1 mol^–1], while AEBH _inf2 ^p2+ is a solvent ordering ion relative to NiAEB²⁺ [s _aq° (NiAEB²⁺) – ovS _aq ° (AEBH _inf2 ^p2+ ) = 11 JK^–1 mol^–1].Author to whom all correspondence should be directed.     

Real‐time Probing the Formation of [M(2,2‐bipyridine)2(NO3)3] (M = Ce,La, Tb) Complexes and Influence of Synthesis Parameters

Despite the strong technological importance of lanthanide complexes, their formation processes are rarely investigated. This work is dedicated to determining the influence of synthesis parameters on the formation of [Ce(bipy)₂(NO₃)₃] as well as Ce³⁺‐ and Tb³⁺‐substituted [La(bipy)₂(NO₃)₃] (bipy = 2,2′‐bipyridine) complexes. To this end, we performed in situ luminescence measurements, synchrotron‐based X‐ray diffraction (XRD) analysis, infrared spectroscopy (IR), and measured pH value and/or ion conductivity during their synthesis process under real reaction conditions. For the [Ce(bipy)₂(NO₃)₃] complex, the in situ luminescence measurements initially presented a broad emission band at 490 nm, assigned to the 5d→4f Ce³⁺ ions within the ethanolic solvation shell. Upon the addition of bipy, a red shift to 700 nm was observed. This shift was attributed to the changes in the environment of the Ce³⁺ ions, indicating their desolvation and incorporation into the [Ce(bipy)₂(NO₃)₃] complex. The induction time was reduced from 8 to 3.5 min, by increasing the reactant concentration by threefold. In contrast, [La(bipy)₂(NO₃)₃] crystallized within days instead of minutes, unless influenced by high Ce³⁺ and Tb³⁺ concentrations. Monitoring and controlling the influence of the reaction parameters on the structure of emissive complexes is important for the development of rational synthesis approaches and optimization of their structure‐related properties like luminescence.     

Construction of two metal coordination polymers based on 1,4-terephthalate and 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene

Two new metal-organic frameworks, namely, Cd(BDC)(Btx) · 0.25(H₂O) (I) and Co₃(BDC)₃(Btx)₄(H₂O)₄ (II) (H₂BDC = 1,4-terephthalate acid and Btx = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene), have been synthesized under hydrothermal conditions and characterized by elemental analysis, IR, TGA, and single crystal X-ray diffraction. Complex I exhibits a scarcely reported an eight-connected (4²⁴.6⁴) net with dinuclear cadmium clusters as secondary building units, whereas complex II displays a three-dimensional co-ordination polymer with a rare (4,6)-connected net described by the (4⁴.6²)₂(4⁸.6⁷) Schläfli symbol. In addition, the luminescence measurements reveal that complex I exhibits strong fluorescent emissions in the solid state at room temperature.     

Synthesis,Structure and Solid-Phase Transformations of Fe Nitrosyl Complex Na<Subscript>2</Subscript>[Fe<Subscript>2</Subscript>(S<Subscript>2</Subscript>O<Subscript>3</Subscript>)<Subscript>2</Subscript>(NO)<Subscript>4</Subscript>] · 4H<Subscript>2</Subscript>O

Binuclear iron nitrosyl complex Na₂[Fe₂(S₂O₃)₂(NO)₄] · 4H₂O (I) was synthesized by the reaction of iron(II) sulfate with sodium thiosulfate in the flow of NO gas. According to X-ray diffraction data, the [Fe₂(S₂O₃)₂(NO)₄]^2– anion has binuclear centrosymmetric structure with Fe atoms bonded by the µ-S atoms of thiosulfate groups. The isomeric shift for complex I =0.168(1) mm/s and quadrupole splitting E _Q =1.288 mm/s at T=80 K. When heated, complex I transforms to Na₂[Fe₂(S₂O₃)₂(NO)₄] (II), whose unit cell parameters found by X-ray diffraction method differ from those of complex I. The process of transformation of I to II was studied by calorimetric method. Complex I transforms to complex II without chemical decomposition, which was confirmed by IR and mass spectroscopy data.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 323–328.Original Russian Text Copyright © 2005 by Sanina, Aldoshin, Rudneva, Golovina, Shilov, Shulga, Martynenko, Ovanesyan.