CsVO2F(IO3): An Excellent SHG Material Featuring an Unprecedented 3D [VO2F(IO3)]− Anionic Framework

The first alkali‐metal vanadium iodate fluoride, CsVO₂F(IO₃), with a novel 3D anionic framework, has been rationally designed and hydrothermally synthesized. The 3D [VO₂F(IO₃)]^? framework in CsVO₂F(IO₃) is built from 0D Λ‐shaped cis‐[VO₃F(IO₃)₂]^4? polyanions via corner‐sharing of oxo anions and bridging of the iodate groups. CsVO₂F(IO₃) displays both a strong second‐harmonic generation (SHG) 1.1 times as strong as KTiOPO₄ (KTP) under 2.05 μm laser radiation and high laser‐induced damage threshold (LIDT) of 107.9 MW cm^?2. This work provides a new route to design SHG crystals with stable 3D anionic structures from low‐dimensional structural building units.     

(NH4)Bi2(IO3)2F5: An Unusual Ammonium‐Containing Metal Iodate Fluoride Showing Strong Second Harmonic Generation Response and Thermochromic Behavior

An ammonium‐containing metal iodate fluoride compound, (NH₄)Bi₂(IO₃)₂F₅, featuring a two‐dimensional double‐layered framework constructed by [BiO₂F₅]^6? and [BiO₄F₄]^9? polyhedra, as well as [IO₃]^? groups, was successfully synthesized. The well‐ordered alignment of these SHG‐active units leads to an extraordinary strong SHG response of 9.2 times that of KDP. Moreover, this compound possesses a large birefringence (Δn=0.0690 at 589.3 nm), a wide energy band gap (E_g=3.88 eV), and a high laser damage threshold (LDT; 40.2×AgGaS₂). In particular, thermochromic behavior was observed for the first time in this type of compound. Such multifunctional crystals will expand the application of nonlinear optical materials.     

CsVO2F(IO3): An Excellent SHG Material Featuring an Unprecedented 3D [VO2F(IO3)]− Anionic Framework

The first alkali-metal vanadium iodate fluoride, CsVO₂F(IO₃), with a novel 3D anionic framework, has been rationally designed and hydrothermally synthesized. The 3D [VO₂F(IO₃)]⁻ framework in CsVO₂F(IO₃) is built from 0D Λ-shaped cis-[VO₃F(IO₃)₂]⁴⁻ polyanions via corner-sharing of oxo anions and bridging of the iodate groups. CsVO₂F(IO₃) displays both a strong second-harmonic generation (SHG) 1.1 times as strong as KTiOPO₄ (KTP) under 2.05 μm laser radiation and high laser-induced damage threshold (LIDT) of 107.9 MW cm⁻². This work provides a new route to design SHG crystals with stable 3D anionic structures from low-dimensional structural building units.     

Bi(IO3)F2: The First Metal Iodate Fluoride with a Very Strong Second Harmonic Generation Effect

The first metal iodate fluoride, Bi(IO₃)F₂, with a strong second harmonic generation (SHG) effect has been prepared. Bi(IO₃)F₂ crystallizes in the polar space group C2 and features a three‐dimensional [BiF₂]⁺ cationic framework with IO₃ groups capping the inner walls of the one‐dimensional tunnels. This [BiF₂]⁺ cationic framework acts as a template for the assembly of the polar IO₃ units in a favorable superposed fashion, which leads to the polar structure of the material. Bi(IO₃)F₂ displays a rather wide transmittance window (0.3–11 μm) and exhibits a very strong SHG response that is about 11.5 times larger than that of KH₂PO₄ (KDP) under 1064 nm laser radiation and the same as that of KTiOPO₄ (KTP) under 2.05 μm laser radiation. Preliminary investigations indicate that Bi(IO₃)F₂ is a promising nonlinear optical material in the visible and mid‐IR region.     

(NH4)Bi2(IO3)2F5: An Unusual Ammonium-Containing Metal Iodate Fluoride Showing Strong Second Harmonic Generation Response and Thermochromic Behavior

An ammonium-containing metal iodate fluoride compound, (NH₄)Bi₂(IO₃)₂F₅, featuring a two-dimensional double-layered framework constructed by [BiO₂F₅]⁶⁻ and [BiO₄F₄]⁹⁻ polyhedra, as well as [IO₃]⁻ groups, was successfully synthesized. The well-ordered alignment of these SHG-active units leads to an extraordinary strong SHG response of 9.2 times that of KDP. Moreover, this compound possesses a large birefringence (Δn=0.0690 at 589.3 nm), a wide energy band gap (E_g=3.88 eV), and a high laser damage threshold (LDT; 40.2×AgGaS₂). In particular, thermochromic behavior was observed for the first time in this type of compound. Such multifunctional crystals will expand the application of nonlinear optical materials.     

Ag9I3(SeO4)2(IO3)2 – Synthesis,Crystal Structure,and Ionic Conductivity

Ag₉I₃(SeO₄)₂(IO₃)₂ was obtained for the first time by reacting a stoichiometric mixture of Ag₂O, AgI and SeO₂ at elevated oxygen pressure (255 MPa) and at a temperature of 500 °C. Ag₉I₃(SeO₄)₂(IO₃)₂ was characterized by X‐ray powder diffraction, differential scanning calorimetry, impedance spectroscopy and single crystal structure analysis. The crystal structure was solved by direct methods (I23, Z = 8, a = 12.9584(6) Å, V = 2175.9(2) ų and R₁ = 2.70 %). The crystal structure consists of isolated SeO₄ tetrahedra and trigonal IO₃ pyramids separated by Ag⁺ and I^– ions. Each four of the SeO₄^2– and IO₃^– anions aggregate, forming a novel supramolecular building block, showing a hetero‐cubane like structure. According to the results of impedance measurements, Ag₉I₃(SeO₄)₂(IO₃)₂ is a good silver ion conductor. The compound shows an abrupt increase in the ionic conductivity in the temperature range of 115 to 147 °C, and has a silver ion conductivity of 7.1 × 10^–5 Ω^–1 cm^–1 at 25 °C. The activation energy for silver ion conduction is 0.45 eV, in the temperature range from 25 to 115°.     

K3V2O3F4(IO3)3: a high-performance SHG crystal containing both five and six-coordinated V5+ cations

The combination of d⁰ transition metal oxofluorides with iodate anions helps to synthesize polar crystals. Herein, a novel polar crystal, K₃V₂O₃F₄(IO₃)₃, which is the first metal vanadium iodate with two types of V⁵⁺-centered polyhedra (VO₄F₂ octahedron and VO₃F₂ trigonal bipyramid), has been prepared hydrothermally. It crystallizes in the polar space group of Cmc2₁ and its structure displays an unprecedented 0D [V₂O₃F₄(IO₃)₃]³⁻ anion, which is composed of Λ-shaped cis-[VO₂F₂(IO₃)₂]³⁻ and [VO₂F₂(IO₃)]²⁻ anions interconnected via the corner-sharing of one oxo anion. The synergy gained from the VO₄F₂, VO₃F₂ and IO₃ groups resulted in K₃V₂O₃F₄(IO₃)₃ exhibiting both a strong second-harmonic generation (SHG) response (1.3 × KTiOPO₄) under 2050 nm laser irradiation and a large birefringence (0.158 @ 2050 nm). This study provides a facile route for designing SHG materials by assembling various vanadium oxide-fluoride motifs and iodate anions into one compound.

K₃V₂O₃F₄(IO₃)₃, which is the first metal vanadium iodate containing two different V-centered polyhedra, exhibits a strong SHG effect of 1.3 × KTP and a large birefringence of 0.158 @ 2050 nm.     

ABi2(IO3)2F5 (A=K,Rb, and Cs): A Combination of Halide and Oxide Anionic Units To Create a Large Second‐Harmonic Generation Response with a Wide Bandgap

A family of nonlinear optical materials that contain the halide, oxide, and oxyhalide polar units simultaneously in a single structure, namely ABi₂(IO₃)₂F₅ (A=K ( 1 ), Rb ( 2 ), and Cs ( 3 )), have been designed and synthesized. They crystallize in the same polar space group (P 2₁) with a two‐dimensional double‐layered framework constructed by [BiF₅]²⁻ and [BiO₂F₄]⁵⁻ units connected to each other by four F atoms, in which two [IO₃]⁻ groups are linked to [BiO₂F₄]⁵⁻ unit on the same side. A hanging Bi−F bond of [BiF₅]²⁻ unit is located on the other side via ionic interaction with the layer‐inserted alkali metal ions to form three‐dimensional structure. The well‐ordered alignments of these polar units lead to a very strong second‐harmonic generation response of 12 ( 1 ), 9.5 ( 2 ), and 7.5 ( 3 ) times larger than that of potassium dihydrogen phosphate under 1064 nm laser radiation. All of them exhibited a wide energy bandgap over 3.75 eV, suggesting that they will have a high laser damage threshold.     

ABi2(IO3)2F5 (A=K,Rb, and Cs): A Combination of Halide and Oxide Anionic Units To Create a Large Second‐Harmonic Generation Response with a Wide Bandgap

A family of nonlinear optical materials that contain the halide, oxide, and oxyhalide polar units simultaneously in a single structure, namely ABi₂(IO₃)₂F₅ (A=K ( 1 ), Rb ( 2 ), and Cs ( 3 )), have been designed and synthesized. They crystallize in the same polar space group (P 2₁) with a two‐dimensional double‐layered framework constructed by [BiF₅]²⁻ and [BiO₂F₄]⁵⁻ units connected to each other by four F atoms, in which two [IO₃]⁻ groups are linked to [BiO₂F₄]⁵⁻ unit on the same side. A hanging Bi−F bond of [BiF₅]²⁻ unit is located on the other side via ionic interaction with the layer‐inserted alkali metal ions to form three‐dimensional structure. The well‐ordered alignments of these polar units lead to a very strong second‐harmonic generation response of 12 ( 1 ), 9.5 ( 2 ), and 7.5 ( 3 ) times larger than that of potassium dihydrogen phosphate under 1064 nm laser radiation. All of them exhibited a wide energy bandgap over 3.75 eV, suggesting that they will have a high laser damage threshold.     

Zinkiodate – Schwingungsspektren (IR,Raman) und Kristallstruktur von Zn(IO3)2 · 2 H2O

Zinc Iodates – Infrared and Raman Spectra, Crystal Structure of Zn(IO₃)₂ · 2 H₂O The zinc iodates Zn(IO₃)₂ · 2 H₂O and Zn(IO₃)₂ as well as α‐Co(IO₃)₂ · 2 H₂O were studied by X‐ray, IR‐ and Raman spectroscopic methods. The crystal structure of the dihydrate, which is isostructural with the respective cobalt compound, was determined by X‐ray single‐crystal studies (space group P1, Z = 2, a = 490,60(4), b = 667,31(5), c = 1088,85(9) pm, α = 98,855(6), β = 91,119(7), and γ = 92,841(6)°, R1 = 2,55%, 2639 unique reflections I > 2σ(I)). Transconfigurated Zn(IO₃)₄(H₂O)₂ octahedra are threedimensionally connected via common IO₃^– ions parallel to [001] and hydrogen bonds parallel to [100] and [010], respectively. Anhydrous Zn(IO₃)₂ crystallizes in space group P2₁ (Z = 2) with a = 548,9(2), b = 512,4(1), c = 941,8(2) pm, and β = 90,5(3)°. The structure of Zn(IO₃)₂ is a monoclinically distorted variant of the structures of β‐Ni(IO₃)₂ (space group P6₃) and Co(IO₃)₂ (P3). The O–H … O–IO₂ hydrogen bonds of the crystallographically different H₂O molecules of the dihydrates (ν_OD (OD stretching modes of isotopically dilute samples) 2430, 2415, 2333 and 2300 cm^–1, Zn(IO₃)₂ · 2 H₂O, 90 K) are examples to the matter of fact that O … O distances are only a bad measure for the strength of hydrogen bonds. The infrared and Raman spectra as well as a group theoretical treatment are presented and discussed with respect to mutual exclusion principle (possible space groups), the strength of the hydrogen bonds and the distortion of the IO₃^– ions at the C₁ lattice sites.     

Das erste quinquinäre Oxoaurat(I) K6Na[IO6][AuO]2 = K6[NaIO6][AuO2/2]2 [1]

Inhaltsübersicht. Bei Versuchen zur Darstellung unbekannter Phasen im System A/Au/I/O (mit A = Alkalimetall) entstanden durch Erhitzen eines Gemenges (2,2 K₂O + 1,0 NaIO₄; Au-Rohr; 700°C, 59 d) farblose, transparente Einkristalle von K₆NaAu₂IO₈, das nach Einkristalldaten (Vierkreisdiffraktometerdaten, 2465 I_o(hkl), AgKα, R = 6,8% und R_w = 5,6%) monoklin in P2/c mit a = 707,4 pm; b = 977,3 pm; c = 1199,4 pm; β = 122,9°; Z = 2 kristallisiert. Charakteristisch sind die hier erstmals gefundenen, HgO-analogen Zickzackketten [AuO_2/2] längs [001]. Daneben prägen, den NaIO₆-Teil der Struktur betreffend, Ketten aus [IO₆]-Oktaeder, über Na in prismatischer Koordination verknüpft, den Aufbau. The First Quinquinary Oxoaurate(I). K₆Na[IO₆][AuO]₂ = K₆[NaIO₆][AuO_2/2]₂ Attempting to synthesize unknown phases in the system A/Au/I/O by heating a mixture of K₂O and NaIO₄ (K: Na = 2.2:1.0, sealed gold tube, 700°C) we obtained colourless, transparent single crystals of K₆NaAu₂IO₆, a new type of Oxoaurate(I). According to single crystal data K₆NaAu₂IO₈ crystallizes in a monoclinic form with a = 707.4 pm, b = 977.3 pm, c = 1199.4 pm β = 122.9° (Z = 2, space group P2/c). Essential part of the structure are chains NaIO₆ and zigzag chains AuO_2/2, both along [001]. The Madelung part of the lattice energy, MAPLE, and effective coordination numbers, ECoN, are calculated and discussed.     

Synthesis and Crystal Structures of α‐ and β‐Mg2[(UO2)3(SeO4)5](H2O)16

Single crystals of α‐ and β‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆ have been synthesized by evaporation from an aqueous solution of the ionic components. The structure of α‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆ (monoclinic, C2/c, a = 19.544(3), b = 10.4783(11), c = 18.020(3) Å, β = 91.352(12)°, V = 3689.3(9) ų) has been solved by direct methods and refined to R₁ = 0.048 on the basis of 4338 unique observed reflections. The structure of β‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆ (orthorhombic, Pbcm, a = 10.3807(7), b = 22.2341(19), c = 33.739(5) Å, V = 7787.2(14) ų) has been solved by direct methods and refined to R₁ = 0.107 on the basis of 3621 unique observed reflections. The structures of α‐ and β‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆ are based upon sheets with the chemical composition [(UO₂)₃(SeO₄)₅]^4‐. The sheets are formed by corner sharing between pentagonal bipyramids [UO₇]^8‐ and SeO₄^2‐ tetrahedra. In the α‐modification, the [(UO₂)₃(SeO₄)₅]^4‐ sheets are more or less planar and run parallel to (001). In the structure of the β‐modification, the uranyl selenate sheets are strongly corrugated and oriented parallel to (010). The [Mg(H₂O)₆]²⁺ polyhedra reside in the interlayers and provide three‐dimensional linkage of the uranyl selenate sheets via hydrogen bonding. In addition to H₂O groups attached to Mg²⁺ cations, both structures also contain H₂O molecules that are not bonded to any cation. The [(UO₂)₃(SeO₄)₅]^4‐ sheets in the structures of α‐ and β‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆ represent two different structural isomers. The sequences of the orientations of the tetrahedra within the sheets can be described by their orientational matrices with their shortened forms ( ddudd □ /uu □ uud ) and ( dd □ dd □ uu □ uu □ /uuduumdduddm ) for α‐ and β‐Mg₂[(UO₂)₃(SeO₄)₅](H₂O)₁₆, respectively. A short review on the isomerism of [(UO₂)₃(TO₄)₅]^4‐ sheets (T = S, Cr, Se, Mo) is given.     

IR- und Raman-Spektren der isotypen Iodathydrate M(IO3)2 · 4 H2O (M = Mg,Ni, Co); Kristallstruktur von Co(IO3)2 · 4 H2O

Infrared and Raman Spectroscopy of the Isostructural Iodate Hydrates M(IO₃)₂ · 4 H₂O (M = Mg, Ni, Co)-Crystal Structure of Cobalt Iodate Tetrahydrate The iodate tetrahydrates Mg(IO₃)₂ · 4 H₂O, β-Ni(IO₃)₂ · 4 H₂O, Co(IO₃)₂ · 4 H₂O and their deuterated specimens were studied by X-ray, infrared and Raman spectroscopic methods. The title compounds are isostructural crystallising in the monoclinic space group P2₁/c (Z = 2). The crystal structure of Co(IO₃)₂ · 4 H₂O (a = 836.8(5), b = 656.2(3), c = 850.2(5) pm and β = 100.12(5)°) has been refined by single-crystal X-ray methods (R_obs = 3.08%, 693 unique reflections I₀ > 2σ(I)). Isolated Co(IO₃)₂(H₂O)₄ octahedra form layers parallel (100). Within these layers, the two crystallographically different hydrate water molecules form nearly linear hydrogen bonds to adjacent IO₃^– ions (ν_OD of matrix isolated HDO of Co(IO₃)₂ · 4 H₂O (isotopically diluted samples) 2443 (H3), 2430 (H2), and 2379 cm^–1 (H1 and H4), –180 °C). Intramolecular O–H and intermolecular H…O distances were derived from the novel ν_OD vs. r_OH and the traditional ν_OD vs. r_H…O correlation curves, respectively. The internal modes of the iodate ions of the title compounds are discussed with respect to their coupling with the librations of the hydrate H₂O molecules, the distortion of the IO₃^– ions, and the influence of the lattice potential.     

LiMII(IO3)3 (MII=Zn and Cd): Two Promising Nonlinear Optical Crystals Derived from a Tunable Structure Model of α‐LiIO3

Excellent nonlinear optical materials simultaneously meet the requirements of large SHG response, phase‐matching capability, wide transparency windows, considerable energy band‐gap, good thermal stability and structure stability. Herein, two new promising nonlinear optical (NLO) crystals LiM^II(IO₃)₃ (M^II=Zn and Cd) are rationally designed by the aliovalent substitution strategy from the commercialized α‐LiIO₃ with the perfect parallel alignment of IO₃ groups. Compared with parent α‐LiIO₃ and related A^I₂M^IV(IO₃)₆, the title compounds exhibit more stable covalent 3D structure, and overcome the racemic twinning problem of A^I₂M^IV(IO₃)₆. More importantly, both compounds inherit NLO‐favorable structure merits of α‐LiIO₃ and show larger SHG response (≈14× and ≈12×KDP), shorter absorption edge (294 and 297 nm) with wider energy band‐gap (4.21 and 4.18 eV), good thermal stability (460 and 430 °C), phase‐matching behaviors, wider optical transparency window and good structure stability, achieving an excellent balance of NLO properties.     

Atom Exchange Versus Reconstruction: (GexAs4−x)x− (x=2, 3) as Building Blocks for the Supertetrahedral Zintl Cluster [Au6(Ge3As)(Ge2As2)3]3−

The Zintl anion (Ge₂As₂)^2? represents an isostructural and isoelectronic binary counterpart of yellow arsenic, yet without being studied with the same intensity so far. Upon introducing [(PPh₃)AuMe] into the 1,2‐diaminoethane (en) solution of (Ge₂As₂)^2?, the heterometallic cluster anion [Au₆(Ge₃As)(Ge₂As₂)₃]^3? is obtained as its salt [K(crypt‐222)]₃[Au₆(Ge₃As)(Ge₂As₂)₃]?en?2 tol ( 1 ). The anion represents a rare example of a superpolyhedral Zintl cluster, and it comprises the largest number of Au atoms relative to main group (semi)metal atoms in such clusters. The overall supertetrahedral structure is based on a (non‐bonding) octahedron of six Au atoms that is face‐capped by four (Ge_xAs_4?x)^x? (x=2, 3) units. The Au atoms bind to four main group atoms in a rectangular manner, and this way hold the four units together to form this unprecedented architecture. The presence of one (Ge₃As)^3? unit besides three (Ge₂As₂)^2? units as a consequence of an exchange reaction in solution was verified by detailed quantum chemical (DFT) calculations, which ruled out all other compositions besides [Au₆(Ge₃As)(Ge₂As₂)₃]^3?. Reactions of the heavier homologues (Tt₂Pn₂)^2? (Tt=Sn, Pb; Pn=Sb, Bi) did not yield clusters corresponding to that in 1 , but dimers of ternary nine‐vertex clusters, {[AuTt₅Pn₃]₂}^4? (in 2 – 4 ; Tt/Pn=Sn/Sb, Sn/Bi, Pb/Sb), since the underlying pseudo‐tetrahedral units comprising heavier atoms do not tend to undergo the said exchange reactions as readily as (Ge₂As₂)^2?, according to the DFT calculations.     

Tetranitratogoldsäure, (H5O2)[Au(NO3)4]·H2O: Synthese,Kristallstruktur und thermisches Verhalten des ersten sauren Nitrates des Goldes

Tetranitratogold(III) Acid, (H₅O₂)[Au(NO₃)₄]·H₂O: Synthesis, Crystal Structure, and Thermal Behaviour of the First Acidic Nitrate of Gold Yellow single crystals of (H₅O₂)[Au(NO₃)₄]·H₂O grow upon cooling of a solution of Au(OH)₃ in conc. nitric acid. The crystal structure contains (monoclinic, C2/c, Z = 4, a = 1214.5(2), b = 854.4(1), c = 1225.7(2) pm, β = 117.75(1)°, R_all = 0.0331) the Au³⁺ ion in coordination of four monodentate NO₃^— ligands. The [Au(NO₃)₄]^— units are linked by H₅O₂⁺‐ions. Significant hydrogen bonding is observed in the crystal structure between the H₅O₂⁺ ions and the H₂O molecules. The thermal analysis reveals a five step decomposition leading to elemental gold.     

Assembly of Three 2D Metal‐Organic Frameworks (MOFs) Derived from Flexible Ligands, 1,4‐bis(3‐pyridyl)‐2,3‐diaza‐1,3‐butadiene (3‐bpd) and/or 1,2‐bis(4‐pyridyl)ethane (dpe)

Three coordination polymers, {[Cd(3‐bpd)₂(NCS)₂]×C₂H₅OH}_n ( 1 ), {[Cd(3‐bpd)(dpe)(NO₃)₂]×(3‐bpd)}₂ ( 2 ), {[Cd(dpe)₂(NCS)₂]×3‐bpd×2H₂O}_n ( 3 ) (3‐bpd = 1,4‐bis(3‐pyridyl)‐2,3‐diaza‐1,3‐butadiene; dpe = 1,2‐bis(4‐pyridyl)ethane), were prepared and structurally characterized by a single‐crystal X‐ray diffraction method. In compound 1 , each Cd(II) ion is six‐coordinate bonded to six nitrogen atoms from four 3‐bpd and two NCS^? ligands. The 3‐bpd acts as a bridging ligand connecting the Cd(II) ion to generate a 2D layered metal‐organic framework (MOF) by using a rhomboidal‐grid as the basic building units with the 4⁴ topology. In compound 2 , the Cd(II) ion is also six‐coordinate bonded to four nitrogen atoms of two 3‐bpd, two dpe and two oxygen atoms of two NO₃^? ligands. The 3‐bpd and dpe ligands both adopt bis‐monodentate coordination mode connecting the Cd(II) ions to generate a 2D layered MOF by using a rectangle‐grid as the basic building units with the 4⁴ topology. In compound 3 , two crystallographically independent Cd(II) ions are both coordinated by four nitrogen atoms of dpe ligands in the basal plane and two nitrogen atom of NCS^? in the axial sites. The dpe acts as a bridging ligand to connect the Cd(II) ions forming a 2D interpenetrating MOFs by using a square‐grid as the basic unit with the 4⁴ topology. All of their 2D layered MOFs in compounds 1 ‐ 3 are then arranged in a parallel non‐interpenetrating ABAB—packing manner in 1 and 2 , and mutually interpenetrating manner in 3 , respectively, to extend their 3D supramolecular architectures with their 1D pores intercalated with solvent (ethanol in 1 or H₂O in 3 ) or free 3‐bpd molecules in 2 and 3 , respectively. The photoluminescence measurements of 1 ‐ 3 reveal that the emission is tentatively assigned to originate from π‐π* transition for 1 and 2 and probably due to ligand‐center luminescence for compounds 3 , respectively.     

Kristallstruktur,Infrarot‐ und Ramanspektren von Kupfertrihydrogenperiodatmonohydrat,CuH3IO6 · H2O

Crystal Structure, Infrared and Raman Spectra of Copper Trihydrogenperiodate Monohydrate, CuH₃IO₆ · H₂O The hitherto unknown compound CuH₃IO₆ · H₂O was studied by X‐ray, IR‐ and Raman spectroscopic methods. The crystal structure was determined by X‐ray single‐crystal studies (space group P2₁2₁2₁, Z = 4, a = 532.60(10), b = 624.00(10), c = 1570.8(3) pm, R1 = 1.85%, 1559 unique reflections (I > 2σ(I))). Isolated, meridionally configurated H₃IO₆^2– ions are coordinated to the copper ions forming double‐ropes in [100]. These ropes are connected in [010] and [001] by hydrogen bonds. The copper ions possess a square pyramidal co‐ordination with the hydrate H₂O on top. The infrared and Raman spectra as well as group theoretical treatment are presented and discussed with respect to the strength of the hydrogen bonds and the co‐ordination of the CuO₅₍₊₁₎ polyhedra and the H₃IO₆^2– ions at the C₁ lattice sites. The hydrogen bonds of the H₂O molecules and H₃IO₆^2– ions (HO–H…O–IO₅H₃ and H₂IO₅O–H…O–IO₅H₃) greatly differ in strength, as shown from both the respective O…O distances: 282.6 and 298.6 pm (H₂O), and 258.8, 259.7, and 270.9 pm (H₃IO₆^2–) and the OD stretching modes of isotopically dilute samples: 2498 and 2564 cm^–1 (90 K) (HDO), and 1786, 2024, and 2188 cm^–1 (H₂DIO₆^2–). The IO stretching modes of the H₃IO₆^2– ions (696–788 cm^–1 and 555–658 cm^–1, 295 K) display the different strength of the respective I–O and I–O(H) bonds (r_I–O: 181.1–188.3 pm and 189.2–194.5 pm).     

Binary salt of a palladium(II) complex with (phosphonomethyl)phosphonic (medronic) acid comprising `handbell‐like' [Pd{μ‐CH2(PO3)2}]3 units

The asymmetric unit of the title compound, dipotassium bis[hexaaquanickel(II)] tris(μ₂‐methylenediphosphonato)tripalladium(II) hexahydrate, K₂[Ni(H₂O)₆]₂[Pd₃{CH₂(PO₃)₂}₃]·6H₂O, consists of half a {[Pd{CH₂(PO₃)₂}]₃}⁶⁻ anion [one Pd atom (4e) and a methylene C atom (4e) occupy positions on a twofold axis] in a rare `handbell‐like' arrangement, with K⁺ and [Ni(H₂O)₆]²⁺ cations to form the neutral complex, completed by three solvent water molecules. The {[Pd{CH₂(PO₃)₂}]₃}⁶⁻ units exhibit close Pd...Pd separations of 3.0469 (4) Å and are packed via intermolecular C—H...Pd hydrogen bonds. The [KO₉] and [NiO₆] units are assembled into sheets coplanar with (011) and stacked along the [100] direction. Within these sheets there are [K₄Ni₄O₈] and [K₂Ni₂O₄] loops. Successive alternation of the sheets and [Pd{CH₂(PO₃)₂}]₃ units parallel to [001] produces the three‐dimensional packing, which is also supported by a dense network of hydrogen bonds involving the solvent water molecules.     

Magnetocaloric Properties of Heterometallic 3d–Gd Complexes Based on the [Gd(oda)3]3− Metalloligand

A series of heterometallic 3d–Gd³⁺ complexes based on a lanthanide metalloligand, [M(H₂O)₆][Gd(oda)₃] ? 3 H₂O [M=Cr³⁺ ( 1‐Cr )] (H₂oda=2,2′‐oxydiacetic acid), [M(H₂O)₆][MGd(oda)₃]₂ ? 3 H₂O [M=Mn²⁺ ( 2‐Mn ), Fe²⁺ ( 2‐Fe ) and Co²⁺ ( 2‐Co )], and [M₃Gd₂(oda)₆(H₂O)₆] ? 12 H₂O [M=Ni²⁺ ( 3‐Ni ), Cu²⁺ ( 3‐Cu ), and Zn²⁺ ( 3‐Zn )], are reported. Magnetic and heat‐capacity studies revealed a significant impact on the magnetocaloric effect depending on the anisotropy of the 3d transition metal ions, as confirmed by comparison of the observed maximum values of ?ΔS_m between complexes 2‐Co and 1‐Cr . In these two complexes, the 3d metal ions have the same spin (S=3/2 for Co²⁺ and Cr³⁺ ions), and the theoretical calculation suggested a larger ?ΔS_m value for 2‐Co (47.8 J K^?1 kg^?1) than 1‐Cr (37.5 J K^?1 kg^?1); however, the significant anisotropy of Co²⁺ ions in 2‐Co , which can result in smaller effective spins, gives a smaller value of ?ΔS_m for 2‐Co (32.2 J K^?1 kg^?1) than for 1‐Cr (35.4 J K^?1 kg^?1) at ΔH=9 T.