Crystal structures of SrLnCuS<Subscript>3</Subscript> (Ln = Gd,Lu)

The crystal-chemical characteristics of new complex sulfides SrLnCuS₃ (Ln = Gd, Lu) are determined from the data of X-ray powder diffraction patterns. SrGdCuS₃ crystallizes in the orthorhombic crystal system (space group Pnma) and belongs to the Eu₂CuS₃ structure type with the unit cell parameters a = 10.3282(8) Å, b = 3.9624(2) Å, and c = 12.9364(9) Å. The structure of SrLuCuS₃ is orthorhombic: the KZrCuS₃ structure type, space group Cmcm, and unit cell parameters are a = 3.9105(2) Å, b = 12.9419(9) Å, and c = 10.0191(8) Å. A substantial role of crystal-chemical contraction inside the [LnCuS₃] dimeric block in the stabilization of structure types based on Eu₂CuS₃ and KZrCuS₃ is shown.     

Crystal structure variations in the series SrLnCuS3 (Ln = La,Pr, Sm,Gd, Er and Lu)

The crystal structures of the complex sulfides SrLnCuS₃ (Ln = Sm, Gd, Er and Lu) have been determined and refined using powder X‐ray diffraction. The crystals are found to be orthorhombic, with the structure type changing consecutively in the order BaLaCuS₃ → Eu₂CuS₃ → KZrCuS₃ as the Ln³⁺ ionic radius decreases in the order La/Pr → Sm/Gd → Er/Lu. Variations of the structure parameters along the series of compounds studied are analyzed, and an effect caused by crystallochemical contraction on the stabilization of the respective structure types is demonstrated.     

Standard molar enthalpies of formation of Ln(C9H6NO)2(C2H3O2) (Ln: Nd, Sm)

Using an on-line solution-reaction isoperibol calorimeter, the standard molar enthalpies of reaction for the general thermochemical reaction: LnCl₃·6H₂O(s) + 2C₉H₇NO(s) + CH₃COONa(s) = Ln(C₉H₆NO)₂(C₂H₃O₂)(s) + NaCl(s) + 2HCl(g) + 6H₂O(l) (Ln: Nd, Sm), were determined at T=298.15 K, as  kJ mol^−l, respectively. From the mentioned standard molar enthalpies of reaction and other auxiliary thermodynamic quantities, the standard molar enthalpies of formation of Ln(C₉H₆NO)₂(C₂H₃O₂)(s) (Ln: Nd, Sm), at T=298.15 K, have been derived to be: −(1494.7±3.3) and −(1501.5±3.4) kJ mol^−l, respectively.     

Crystal Structure and Vibrational Spectrum of Thallium(I) Europium(II) Tetrathiophosphate(V), TIEu[PS4]

TlEu[PS₄] was synthesized from the elements in a sealed quartz ampoule at 1 150 K. The compound forms transparent orange needles, stable in air and moisture. It crystallizes in the orthorhombic system, space group Pnma (No. 62), with cell dimensions a = 12.157(2), b = 6.581(1), c = 8.802(2) Å, Z = 4. The crystal structure consists of discrete [PS₄]^3? anions interconnected by Tl⁺ and Eu²⁺. The tetrahedral [PS₄]^3? groups are slightly distorted with P? S bond lengths in the range 2.028 to 2.043 Å. These tetrahedral anions are arranged in such a way that the sulfur atoms form columns of distorted trigonal S₆ prisms along [0 0 1]. The columns are condensed via common edges to puckered layers parallel to (1 0 0). The interlayer region consists of empty distorted half-cubes and tetrahedral holes, half of them filled by P atoms. The trigonal prisms in the columns are centered alternately by Tl⁺ and Eu²⁺. In this way, the structure can be regarded as an ordered superstructure of the InNi₂ type, where half of the tetrahedral holes are filled by phosphorus atoms: InInNi₄□ ? TlEuS₄P□. TlEu[PS₄] is a centrosymmetric variant of the TlSn[PS₄] structure type (space group Pna2₁). The vibrational spectrum is in accordance with the X-ray crystal structure, the Raman and infrared vibrations are assigned on the basis of [PS₄]^3? units with C_2v symmetry.     

Preparation and properties of rare-earth-molybdenum(V) oxides Ln3MoO7

Phase equilibrium studies in Ln₂O₃MoO₂MoO₃ systems indicate, for a Ln₂O₃:Mo ratio of 3:2, the existence of a new molybdenum (V)-rare-earth oxide Ln₃MoO₇. Ternary oxides have been prepared for Ln ≡ La-Ho and Y. For Ln ≡ La-Eu, Ln₃MoO₇ compounds form at 1473 K under oxygen partial pressures ranging from 10^−7.3 to 10^−11.6 atm. For Ln ≡ Gd-Ho and Y compounds form above 1573 K and at 1473 K the stability range is about 10⁻⁹ to about 10⁻¹⁰ atm. Lattice parameters deduced from X-ray diffraction patterns are reported. For the large Ln cations, lanthanum to europium, all reflections could be indexed in an orthorhombic C-centred cell isotypic to Nd₃NbO₇. For Ln ≡ Gd-Ho and Y, strong f.c.c.-type reflections show that the structure is defect fluorite. Stability ranges in terms of oxygen partial pressure and crystal chemical properties are discussed with respect to the rare-earth elements. Magnetic susceptibility measurements of La₃MoO₇ confirm the oxidation state + 5 for molybdenum.     

Crystal structures of EuLnCuS<Subscript>3</Subscript> (Ln = Nd and Sm)

The compound sulfides EuLnCuS₃ (Ln = Nd and Sm) were obtained for the first time. Their crystal structures were determined from X-ray powder diffraction data. The crystals of both compounds are orthorhombic (space group Pnma). The compound EuNdCuS₃ is isostructural with BaLaCuS₃; the unit cell parameters are a = 11.0438(2) Å, b = 4.0660(1) Å, c = 11.4149(4) Å. The compound EuSmCuS₃ is isostructural with Eu₂CuS₃; the unit cell parameters are a = 10.4202(2) Å, b = 3.9701(1) Å, c = 12.8022(2) Å.     

Crystal structure of EuLnAgS<Subscript>3</Subscript> (Ln = Gd and Ho) compounds

The crystal structures of the first prepared EuLnAgS₃ (Ln = Gd and Ho) compounds, which have two polymorphs, were determined by X-ray powder diffraction. α-EuLnAgS₃ phases are isostructural to BaErAgS₃ (monoclinic crystal system, space group C2/m): a = 17.3168(10) Å, b = 3.9683(2) Å, c = 8.3174(4) Å, β = 103.94° (EuGdCuS₃); a = 17.1729(12) Å, b = 3.9367(3) Å, c = 8.2905(6) Å, β = 103.9° (EuHoCuS₃). β-EuLnAgS₃ phases belong to the AgBiS₂ structure type (cubic crystal system, space group Fm-3m): a = 5.739(2) Å (EuGdCuS₃) and a = 5.678 Å (EuHoCuS₃). In the α-EuLnAgS₃ crystal structure, LnS₆ octahedra and AgS₅ trigonal bipyramids share edges to form a three-dimensional (3D) structure with channels accommodating Eu²⁺ ions. A decrease in Ln³⁺ ionic radius gives rise to the crystal-chemical contraction of the 3D structure.     

Chemiluminescence and catalysis of decomposition of dispiro(diadamantane-1,2-dioxetane) in the presence of EuIII and TbIII tris(benzoyltrifluoroacetonate) complexes

Catalysis of decomposition of dispiro(diadamantane-1,2-dioxetane) (1) in the presence of Eu^III and Tb^III tris(benzoyltrifluoroacetonate) complexes (Ln(btfa)₃) accompanied by the formation of adamantanone (2) and chemiluminescence (CL) was studied. The rate constants (k ₂) of decomposition of compound1 in the1·Ln(btfa)₃ complexes and their stability constants (K ₁) have been determined. The Arrhenius parameters of decomposition of1 (E _a= 22.4±0.7 kcal mol^?1, logA=10.2±0.8 for1·Tb(btfa)₃ andE _a=23.4±0.6 kcal mol^?1, logA=10.6±0.8 for1·Eu(btfa)₃) and thermodynamic parameters of complex formation (ΔH=?5.5±0.5 kcal mol^?1, ΔS=?10.4±0.7 e.u. for1·Tb(btfa)₃ and ΔH=?5.8±0.5 kcal mol^?1, ΔS=?10.9±0.7 e.u. for1·Eu(btfa)₃) have been calculated from the temperature dependences ofk ₂ andK ₁. The yields of excitation of the Ln(btfa)₃ chelates φ _Eu ^* =0.021±0.006 and φ _Tb ^* =0.12±0.04 have been determined. A higher efficiency of the occupation of the⁵D₄-level of Tb³⁺ compared to those of the⁵D₁- and⁵D₀-levels of Eu³⁺ is caused by different efficiencies of the non-radiative energy dissipation in the Ln³⁺ ion after the intracomplex energy transfer from the³n,π^*-state of2 to the resonance excited levels of lanthanides.     

A morphotropic series of the cluster complexes [Ln(DMF)8][Re6Q7Br7] (Q = S, Se): Synthesis, structure, and thermal transformations

The reactions of the octahedral anionic complexes [Re₆Q₇Br₇]^3? (Q = S, Se) with lanthanide bromides in DMF were studied. The reactions gave a series of compounds [Ln(DMF)₈][Re₆Q₇Br₇] (Q = S, Se) containing [Ln(DMF)₈]³⁺ complex cations. The compounds were studied by single-crystal and powder X-ray diffraction and thermal analyses. The crystal structures of [Ln(DMF)₈][Re₆S₇Br₇] with Ln = La (I), Ce (II), Nd (III), Eu (IV), and Lu (V) and [Ln(DMF)₈][Re₆Se₇Br₇] with Ln = La (VI), Ce (VII), Pr (VIII), and Lu (IX) were determined. It was found that [Ln(DMF)₈][Re₆Q₇Br₇] (Q = S, Se) can be divided into three structural groups: I, II, and VI (type A), VII (type B), and III–V, VIII, IX (type C). The complex [Pr(DMF)₈][Re₆Se₇Br₇] was found to crystallize in two polymorphous modifications with type B and C structures. Presumably, the morphotropic transitions in the [Ln(DMF)₈][Re₆Q₇Br₇] series (Q = S, Se) are mainly related to the change in the configuration of the [Ln(DMF)₈]³⁺ cations, resulting in a change in the packing motif of large complex ions in the crystals. The compounds [Ln(DMF)₈][Re₆Se₇Br₇] decompose according to a stepwise pattern, which suggests an intermediate formation of the complexes [Ln(DMF)₆][Re₆Se₇Br₇] (this was proved for Ln = Yb, Lu) with subsequent more extensive transformations, which affect also the cluster anion.     

The Series of Rare Earth Complexes [Ln2Cl6(μ‐4,4′‐bipy)(py)6], Ln=Y,Pr, Nd,Sm‐Yb: A Molecular Model System for Luminescence Properties in MOFs Based on LnCl3 and 4,4′‐Bipyridine

A series of 12 dinuclear complexes [Ln₂Cl₆(μ‐4,4′‐bipy)(py)₆], Ln=Y, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, ( 1 – 12 , respectively) was synthesized by an anhydrous solvothermal reaction in pyridine. The complexes contain a 4,4′‐bipyridine bridge and exhibit a coordination sphere closely related to luminescent lanthanide MOFs based on LnCl₃ and 4,4‐bipyridine. The dinuclear complexes therefore function as a molecular model system to provide a better understanding of the luminescence mechanisms in the Ln‐N‐MOFs ${\hbox{}{{\hfill 2\atop \hfill \infty }}}$ [Ln₂Cl₆(4,4′‐bipy)₃] ? 2(4,4′‐bipy). Accordingly, the luminescence properties of the complexes with Ln=Y, Sm, Eu, Gd, Tb, Dy, ( 1 , 4 – 8 ) were determined, showing an antenna effect through a ligand–metal energy transfer. The highest efficiency of luminescence is observed for the terbium‐based compound 7 displaying a high quantum yield (QY of 86 %). Excitation with UV light reveals typical emission colors of lanthanide‐dependent intra 4f–4f‐transition emissions in the visible range (Tb^III: green, Eu^III: red, Sm^III: salmon red, Dy^III: yellow). For the Gd^III‐ and Y^III‐containing compounds 6 and 1 , blue emission based on triplet phosphorescence is observed. Furthermore, ligand‐to‐metal charge‐transfer (LMCT) states, based on the interaction of Cl^? with Eu^III, were observed for the Eu^III compound 5 including energy‐transfer processes to the Eu^III ion. Altogether, the model complexes give further insights into the luminescence of the related MOFs, for example, rationalization of Ln‐independent quantum yields in the related MOFs.     

Phase equilibria in BaF2(Y,Ln)F3 systems

Data are presented on phase equilibria at 877 ± 10°C in the systems BaF₂(Y,Ln)F₃, where Ln = SmLu. All the systems show cubic solid solutions based on BaF₂ and variable composition phases

of structure derived from the CaF₂ type (rhombohedral distortion). Syngony and unit cell dimensions have been determined on monocrystals; crystallographic parameters of ten trigonal phases have been adduced. The existence of solid solutions of BaF₂ in high-temperature α-LnF₃(LaF₃ type) at the given isothermal section indicates stabilization of the LaF₃ structure type by heterovalent isomorphous replacement. In the systems BaF₂(Y,Ln)F₃ with Ln = DyYb, monoclinic compounds BaR₂F₈ are formed. X-ray parameters, derived from single crystal and polycrystalline specimens, of six monoclinic BaR₂F₈ compounds are presented. In the BaF₂LuF₃ system we have isolated and studied for the first time a compound of the approximate composition BaLu₂F₈ which crystallizes in rhombic syngony and has a marked range of homogeneity.     

Ln(III) metal-organic frameworks with 5-nitroisophthalate ligands: Crystal structures and luminescent properties

Two new Ln(III) metal-organic frameworks (MOFs) based on 5-nitroisophthalic acid (H₂L), namely [Pr₄(L)₆(H₂O)₄] _n (I) and [Gd(L)(FA)(H₂O)₂] _n (II) (HFA = formic acid), were prepared by solvothermal reactions and structurally characterized by IR, elemental analysis, XRD, and single crystal X-ray diffraction (CIF files CCDC nos. 971379 (I) and 971380 (II)). A 3D {4.6²}{4¹⁰.6¹⁷.8⁹}{4³}₂ topology framework of I and a 3D {4.6² ₂}{4².6¹⁰.8³} topology network of II are constructed respectively with different synthetic conditions. Four kinds of coordination modes are observed for dicarboxylate in these two MOFs in total. Notably, the in situ hydrolysis of DMF solvates leads to the formation of formate ions that was observed in the structure of II. Moreover, the luminescent properties of both complexes and corresponding ligand have been investigated.     

Complexes of actinides and lanthanides in lower oxidation states with sodium tetraphenylborate

The stabilizing effect of sodium tetraphenylborate (NaBPh₄) in relation to aqueous and aqueous-ethanolic solution of Ln²⁺ and An²⁺ as well as U³⁺ has been studied. It was determined that stabilization of Ln²⁺ and An²⁺ occuured due to the formation of outer-sphere complexes of a [M(H₂O)_n](BPh₄)₂(M=Ln and An) composition. Stability constants ₁ and ₂ equal to 6.5 and 25.7 for Yb²⁺; 1.7 and 52.7 for Eu²⁺; 6.2 and 106.4 for Es²⁺, respectively were found. The assumption was made that stabilazation of Ln²⁺, An²⁺ and U³⁺ in water mainly occurs due to steric effects.     

Effect of lanthanide contraction on the mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien): Syntheses and characterizations of lanthanide complexes with a tetraelenidoantimonate ligand

Mixed polyamine systems Ln/Sb/Se/(en+dien) and Ln/Sb/Se/(en+trien) (Ln=lanthanide, en=ethylenediamine, dien=diethylenetriamine, trien=triethylenetetramine) were investigated under solvothermal conditions, and novel mixed-coordinated lanthanide(III) complexes [Ln(en)₂(dien)(η²-SbSe₄)] (Ln=Ce(1a), Nd(1b)), [Ln(en)₂(dien)(SbSe₄)] (Ln=Sm(2a), Gd(2b), Dy(2c)), [Ln(en)(trien)(μ-η¹,η²-SbSe₄)]_∞ (Ln=Ce(3a), Nd(3b)) and [Sm(en)(trien)(η²-SbSe₄)] (4a) were prepared. Two structural types of lanthanide selenidoantimonates were obtained across the lanthanide series in both en+dien and en+trien systems. The tetrahedral anion [SbSe₄]³⁻ acts as a monodentate ligand mono-SbSe₄, a bidentate chelating ligand η²-SbSe₄ or a tridentate bridging ligand μ-η¹,η²-SbSe₄ to the lanthanide(III) center depending on the Ln³⁺ ions and the mixed ethylene polyamines, indicating the effect of lanthanide contraction on the structures of the lanthanide(III) selenidoantimonates. The lanthanide selenidoantimonates exhibit semiconducting properties with E_g between 2.08 and 2.51 eV.     

Research on Molecular Structure and Electronic Properties of Ln3+ (Ce3+, Tb3+, Pr3+)/Li+ and Eu2+ Co-Doped Sr2Si5N8 via DFT Calculation

We use density functional theory (DFT) to study the molecular structure and electronic band structure of Sr₂Si₅N₈:Eu²⁺ doped with trivalent lanthanides (Ln³⁺ = Ce³⁺, Tb³⁺, Pr³⁺). Li⁺ was used as a charge compensator for the charge imbalance caused by the partial replacement of Sr²⁺ by Ln³⁺. The doping of Ln lanthanide atom causes the structure of Sr₂Si₅N₈ lattice to shrink due to the smaller atomic radius of Ln³⁺ and Li⁺ compared to Sr²⁺. The doped structure’s formation energy indicates that the formation energy of Li⁺, which is used to compensate for the charge imbalance, is the lowest when the Sr2 site is doped. Thus, a suitable Li⁺ doping site for double-doped lanthanide ions can be provided. In Sr₂Si₅N₈:Eu²⁺, the doped Ce³⁺ can occupy partly the site of Sr₁²⁺ ([SrN₈]), while Eu²⁺ accounts for Sr₁²⁺ and Sr₂²⁺ ([SrN₁₀]). When the Pr³⁺ ion is selected as the dopant in Sr₂Si₅N₈:Eu²⁺, Pr³⁺ and Eu²⁺ would replace Sr₂²⁺ simultaneously. In this theoretical model, the replacement of Sr²⁺ by Tb³⁺ cannot exist reasonably. For the electronic structure, the energy level of Sr₂Si₅N₈:Eu²⁺/Li⁺ doped with Ce³⁺ and Pr³⁺ appears at the bottom of the conduction band or in the forbidden band, which reduces the energy bandgap of Sr₂Si₅N₈. We use DFT+U to adjust the lanthanide ion 4f energy level. The adjusted 4f-CBM of Ce_Sr1Li_Sr1-Sr₂Si₅N₈ is from 2.42 to 2.85 eV. The energy range of 4f-CBM in Pr_Sr1Li_Sr1-Sr₂Si₅N₈ is 2.75–2.99 eV and its peak is 2.90 eV; the addition of Ce³⁺ in Eu_Sr1Ce_Sr1Li_Sr1 made the 4f energy level of Eu²⁺ blue shift. The addition of Pr³⁺ in Eu_Sr2Pr_Sr2Li_Sr1 makes part of the Eu²⁺ 4f energy level blue shift. Eu²⁺ 4f energy level in Eu_Sr2Ce_Sr1Li_Sr1 is not in the forbidden band, so Eu²⁺ is not used as the emission center.     

Neue Phosphate mit Eulytinstruktur,insbesondere Europium(II)-Verbindungen [1]

New Phosphates with Eulytine Structure, especially Europium(II) Compounds. A number of Eu(II) phosphates EuLn(PO₄)₃ have been prepared, where Ln? La, lanthanides, Y. All investigated compounds have colours from yellow to ockre and crystallize with the cubic structure of eulytine (Bi₄(SiO₄)₃). Eu(PO₄)₃ makes an exception, showing a lattice deformation to low symmetry. It converts to a cubic eulytine phase by partial oxydation. The peculiar run of the lattice constants of the Eu(II) compounds in the lanthanide series is compared with the behaviour of the analogous Sr, Pb, and Ba compounds. Moreover, the eulytine compounds Pb₃M^III(PO₄)₃ with M^III? V, Cr, Fe have been synthesized. Experiments with Ti^III yield solid solutions between Pb₃Ti^III(PO₄)₃ and Pb₇Ti^IV(PO₄)₆.     

Ln2(ClO4)2(H2I2O10) · 8H2O (Ln = Sm,Gd), a Lanthanide Perchlorate Mesodiperiodate forming a Novel Layer Structure

By slow evaporation of solutions containing Ln(ClO₄)₃ (Ln = Sm, Gd), H₅IO₆ and an excess of HClO₄, crystals of the title compounds could be obtained. Their structures were determined by single‐crystal X‐ray diffraction. The compounds crystallize in the monoclinic crystal system, space group P2₁/c. They contain Ln³⁺ ions, which are coordinated by [H₂I₂O₁₀]^4— anions forming two‐dimensional, cationic networks. These are separated by perchlorate ions, forming a layered structure.     

Di- and tetranuclear heterometallic CuII-LnIII complexes (Ln = Gd and Dy): Synthesis, structure and magnetic properties

Four 3d-4f heterometallic complexes, [CuⅡ LnⅢ (bpt) 2 (NO 3 ) 3 (MeOH)] (Ln = Gd, 1; Dy, 2; bptH = 3,5-bis(pyrid-2-yl)-1,2,4- triazole), [CuⅡ 2 LnⅢ 2 (μ-OH) 2 (bpt) 4 Cl 4 (H 2 O) 2 ]·6H 2 O (Ln = Gd, 3; Dy, 4), have been synthesized under solvothermal conditions. X-ray structural analyses reveal that 1 and 2 are isostructural while 3 and 4 are isostructural. In each complex, the copper and gadolinium or dysprosium ions are linked by two triazolate bridges and form a CuⅡ -LnⅢ dinuclear unit. The intramolecular Cu-Ln distances are 4.542, 4.525, 4.545 and 4.538 for 1, 2, 3 and 4, respectively. Two dinuclear CuLn units are bridged by two OH- groups into the zig-zag tetranuclear {CuⅡ 2 LnⅢ 2 } structures with the Ln(Ⅲ) Ln(Ⅲ) distances of 3.742 and 3.684 for 3 and 4, respectively. Magnetic studies show that the antiferromagnetic CuⅡ-LnⅢ interactions occur in 1 (J CuGd = 0.21 cm-1 ) and 2. The antiferromagnetic interaction occurs in complex 3 with J CuGd = 0.82 cm-1 and J GdGd = 0.065 cm-1 , while dominant ferromagnetic interaction occurs in complex 4.