The Inverse Perovskite Nitrides (Sr3N2/3–x)Sn, (Sr3N2/3–x)Pb,and (Sr3N)Sb: Flux Crystal Growth,Crystal Structures,and Physical Properties

Black single crystals with metallic luster of (Sr₃N_2/3–x)E (E = Sn, Pb) and (Sr₃N)Sb were grown in lithium flux from strontium nitride, Sr₂N, and tin, lead, or antimony, respectively. Nitrogen deficiency in the tin and the lead compound is a result of the higher ionic charge of the tetrelide ions E^4– as compared to the antimonide ion Sb^3–. In contrast to microcrystalline samples from solid state sinter reactions obtained earlier, the flux synthesis induces nitrogen order in the nitrogen deficient tetrelides. The antimony compound crystallizes as inverse cubic perovskite [a = 517.22(5) pm, Z = 1, space group Pm3 m, no. 221] with fully occupied nitrogen site, whereas the nitrogen deficient tin and lead compounds exhibit partially ordered arrangements and a certain phase width in respect to nitrogen contents. For the tetrelides, the nitrogen order leads to a cubic 2 × 2 × 2 superstructure [E = Sn: a = 1045.64(8) pm for x = 0, a = 1047.08(7) pm for x = 0.08; and E = Pb: a = 1050.7(1) pm for x = 0, space group Fm3 m, no. 225] as derived from single‐crystal X‐ray diffraction data. The metallic tetrelides show diamagnetic behavior, which is consistent with electronic structure calculations.     

Synthesis and Crystal Structure of α‐ThTe3

The binary thorium tritelluride, α‐ThTe₃, was synthesized by solid‐state methods at 1223 K. From a single‐crystal X‐ray diffraction study the material crystallizes in the TiS₃ structure type with two formula units in space group C²_2h–P2₁/m of the monoclinic system in a cell with lattice constants a = 6.1730 (4) Å, b = 4.3625(3) Å, c = 10.4161(6) Å, and β = 97.756(3)° (at 100 K). The asymmetric unit of this compound comprises one Th atom and three Te atoms each with site symmetry m. Each Th atom is coordinated to eight Te atoms in a bicapped trigonal‐pyramidal arrangement. Th–Te distances range from 3.1708(4) Å to 3.2496(6) Å. The structure features a Te–Te interaction 2.7631(8) Å in length, which is typical for a Te–Te single bond. Thus α‐ThTe₃ may be charge balanced and formulated as Th⁴⁺Te^2–Te₂^2–.     

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.     

Reactivity Studies of η5‐ Indenyl and η5‐Cp* Ruthenium(II) Complexes towards some Polypyridyl Ligands

The reaction of [(η⁵‐L³)Ru(PPh₃)₂Cl], where; L³ = C₉H₇ ( 1 ), C₅Me₅ (Cp*) ( 2 ) with acetonitrile in the presence of [NH₄][PF₆] yielded cationic complexes [(η⁵‐L³)Ru(PPh₃)₂(CH₃CN)][PF₆]; L³= C₉H₇ ([3]PF₆) and L³ = C₅Me₅ ([4]PF₆), respectively. Complexes [3]PF₆ and [4]PF₆ reacts with some polypyridyl ligands viz, 2,3‐bis (α‐pyridyl) pyrazine (bpp), 2,3‐bis (α‐pyridyl) quinoxaline (bpq) yielding the complexes of the formulation [(η⁵‐L³)Ru(PPh₃)(L²)]PF₆ where; L³ = C₉H₇, L² = bpp, ([5]PF₆), L³ = C₉H₇, L² = bpq, ([6]PF₆); L³ = C₅Me₅, L² = bpp, ([7]PF₆) and bpq, ([8]PF₆), respectively. However reaction of [(η⁵‐C₉H₇)Ru(PPh₃)₂(CH₃CN)][PF₆] ([3]PF₆) with the sterically demanding polypyridyl ligands, viz. 2,4,6‐tris(2‐pyridyl)‐1,3,5‐triazine (tptz) or tetra‐2‐pyridyl‐1,4‐pyrazine (tppz) leads to the formation of unexpected complexes [Ru(PPh₃)₂(L²)(CH₃CN)][PF₆]₂; L² = tppz ([9](PF₆)₂), tptz ([11](PF₆)₂) and [Ru(PPh₃)₂(L²)Cl][PF₆]; L² = tppz ([10]PF₆), tptz ([12]PF₆). The complexes were isolated as their hexafluorophosphate salts. They have been characterized on the basis of micro analytical and spectroscopic data. The crystal structures of the representative complexes were established by X‐ray crystallography.     

Crystal and Molecular Structures of Two Derivatives of 1, 3a, 5-Trisubstituted-3a ,4,5,11-Tetrahydro-1,2,4-Oxadiazolino[5,4-d] [1, 5]Benzothiazepine

The structures of two derivatives of the title compound [C24H22N2OS, Mr = 386. 5 for (1); C25H22N2O3S, Mr = 430. 5 for (2)] were determined by using X-ray single-crystal strcuture analysis method. The final discrepancies are R = 0. 071 and 0. 077, respectively, for the reflections measured on a four-circle diffractometer. The space group for compound (1) is P bca with a=1. 6639(4), b=2.0286(3), c= 1.1742(1) nm, V = 3. 964(1) nm3, F(000) = 1632 e, Z=8; and (2) belongs to P21/n space group, and the cell dimensions are a=1. 1115(4), b=0. 8932(7), c=2. 186(3) nm, β=97. 52 (1)°? V=2.151(4) nm3, F(000) = 904 e, Z=4.The molecular backbones are very similar, each is a tricyclic system. The central seven-membered ring is in a twisted-boat conformation, and is cis-fused to 1,2,4-oxa-diazolino ring, while the latter moiety is in an envelope form. There are conjugated but non-coplanar effects in each structure. All bond lengths and angles in the molecules are normally acceptable. The crystal structure on the whol     

Crystal Structures of NbOI3 and NbOBr3 – Polar Double Chains in Different Non‐centrosymmetric Structures

NbOI₃ was obtained from a reaction of Nb₂O₅, Nb, and I₂. Single crystals free from disorder were a by‐product from a reaction with additional CsI. The monoclinic crystal structure (C2, a = 14.624(3) Å, b = 3.9905(8) Å, c = 12.602(3) Å, β = 120.4(3)°, Z = 4, R₁(F) = 0.0368, wR₂(F²) = 0.0804) represents a new structure type which is built up by distorted octahedral NbI₄O₂ with unequal O‐atoms in trans‐position. The octahedra are linked to dimers by a common edge of iodine atoms and to double chains by the apical oxygen atoms. A non‐centrosymmetric structure results because the short Nb–O distances point to the same direction and the polar double chains are parallel. The crystal structure of NbOBr₃ (NbOCl₃‐type, , a = 11.635(6) Å, c = 3.953(2) Å, R₁(F) = 0.082, wR₂(F²) = 0.174) shows the same polar double chains but the dimeric units Nb₂Br₆O₂ are orthogonal.     

Synthesis,Crystal Structures,and Luminescent Properties of Two Complexes based on 5‐tert‐Butylisophthalic Acid and 1, 2‐Bis(4‐pyridyl) Ethane

Abstract. Two coordination polymers, namely, [Zn(bpe)_0.5(Htbip)(tbip)_0.5] · H₂O ( 1 ) and [Cd(bpe)_0.5(tbip)] ( 2 ) [H₂tbip = 5‐tert‐butylisophthalic acid and bpe = 1, 2‐ bis(4‐pyridyl) ethane] were synthesized through hydrothermal reactions. Single‐crystal X‐ray diffraction analysis reveals that complex 1 presents a three‐dimensional (3D) six‐connected uninodal structure with the type of topology of svi‐x/I4/mcm → Ibam, whereas complex 2 holds a 2D 4⁴‐sql layer structure. Moreover, the photoluminescent properties of the complexes at room temperature were investigated.     

The Binary Silicides Eu5Si3 and Yb3Si5 – Synthesis,Crystal Structure,and Chemical Bonding

The binary silicides Eu₅Si₃ and Yb₃Si₅ were prepared from the elements in sealed tantalum tubes and their crystal structures were determined from single crystal X-ray data: I4/mcm, a = 791.88(7) pm, c = 1532.2(2) pm, Z = 4, wR2 = 0.0545, 600 F² values, 16 variables for Eu₅Si₃ (Cr₅B₃-type) and P62m, a = 650.8(2) pm, c = 409.2(1) pm, Z = 1, wR2 = 0.0427, 375 F² values, 12 variables for Yb₃Si₅ (Th₃Pd₅ type). The new silicide Eu₅Si₃ contains isolated silicon atoms and silicon pairs with a Si–Si distance of 242.4 pm. This silicide may be described as a Zintl phase with the formula [5 Eu²⁺]¹⁰⁺[Si]^4–[Si₂]^6–. The silicon atoms in Yb₃Si₅ form a two-dimensional planar network with two-connected and three-connected silicon atoms. According to the Zintl-Klemm concept the formula of homogeneous mixed-valent Yb₃Si₅ may to a first approximation be written as [3 Yb]⁸⁺[2 Si^–]^2–[3 Si^2–]^6–. Magnetic susceptibility investigations of Eu₅Si₃ show Curie-Weiss behaviour above 100 K with a magnetic moment of 7.85(5) μ_B which is close to the free ion value of 7.94 μ_B for Eu²⁺. Chemical bonding in Eu₅Si₃ and Yb₃Si₅ was investigated by semi-empirical band structure calculations using an extended Hückel hamiltonian. The strongest bonding interactions are found for the Si–Si contacts followed by Eu–Si and Yb–Si, respectively. The main bonding characteristics in Eu₅Si₃ are antibonding Si1₂-π* and bonding Eu–Si1 states at the Fermi level. The same holds true for the silicon polyanion in Yb₃Si₅.     

Crystal Structure of Di[(μ‐benzoato‐O,O′)bis(η5‐methylcylopentadienyl)ytterbium(III)]

Transparent orange‐red crystals of [Yb(MeCp)₂(O₂CPh)]₂ obtained by oxidation of Yb(MeCp)₂ with Tl(O₂CPh) in tetrahydrofuran have a dimeric structure with bridging bidentate (O,O′)‐benzoate groups and eight‐coordinate ytterbium.     

Mixed‐Valence Thallium(I,III) Bromides The Crystal Structure of α—Tl2Br3

Thallium sesquibromide Tl₂Br₃ is dimorphic. Scarlet coloured crystals of α‐Tl₂Br₃ were obtained by reactions of aqueous solutions of TlBr₃ and Tl₂SO₄ in agarose gel. In case of rapid crystallisation of hydrous TlBr₃/TlBr solutions and from TlBr/TlBr₂ melts ß‐Tl₂Br₃ is formed as scarlet coloured, extremely thin lamellae. The crystal structures of both forms are very similar and can be described as mixed‐valence thallium(I)‐hexabromothallates(III) Tl₃[TlBr₆]. In the monoclinic unit cell of α‐Tl₃[TlBr₆] (a = 26.763(7) Å; b = 15.311(6) Å; c = 27.375(6) Å; β = 108.63(2)°, Z = 32, space gr. C2/c) the 32 Tl^III‐cations are found in strongly distorted octahedral TlBr₆ groups. The 96 Tl^I cations are surrounded either by four or six TlBr₆ groups with contacts to 8 or 9 Br neighbors. Crystals of β‐Tl₃[TlBr₆] by contrast show almost hexagonal metrics (a = 13.124(4) Å, b = 13.130(4) Å, c = 25.550(7) Å, γ = 119.91(9)°, Z = 12, P2₁/m). Refinements of the parameters revealed structural disorder of TlBr₆ units, possibly resulting from multiple twinning. Both structures are composed of Tl₂[TlBr₆]^— and Tl₄[TlBr₆]⁺ multilayers, which alternate parallel (001). The structural relationships of the complicated structures of α‐ and β‐Tl₃[TlBr₆] to the three polymorphous forms of Tl₂Cl₃ as well as to the structures of monoclinic hexachlorothallates M₃TlCl₆ (M = K, Rb) and the cubic elpasolites are discussed.     

Syntheses,Structures, and Polymorphism of β‐Diketonato Complexes – Co(thd)3

Oxidation of Co(thd)₂ dissolved in different solvents has been investigated in air and oxygen atmosphere. In oxygen atmosphere and at the boiling point of the solvents this treatment leads to oxidation of Co^II to Co^III, but also to degradation of some of the thd ligands and formation of a new mixed‐ligand complex. Three pure‐cultivated crystalline Co(thd)₃ phases are reported: 1 (room‐temperature phase), 2 (low‐temperature phase), and 3 (metastable phase) and in addition there exists an amorphous Co(thd)₃ phase ( 4 ) with approximate composition Co(thd)₃·xH(thd); x = 0.06. Reaction of metal(II) oxides (MO, M = Mn, Fe, and Co) with H(thd) under air or O₂ atmosphere is an easy direct route to M(thd)₃ complexes. Structure determinations are reported for Co(thd)₃ ( 1 – 3 ) based on single‐crystal X‐ray diffraction data. Modification 1 crystallizes in space group with a = b = 18.8100(10), c = 18.815(2) Å at 295 K; R(wR2) = 0.180, modification 2 in space group C2/c with a = 28.007(12), b = 18.482(8), c = 21.356(9) Å, β = 97.999(5)° at 100 K; R(wR2) =0.211, and modification 3 in space group Pnma with a = 19.2394(15), b = 18.8795(15), c = 10.7808(8) Å at 100 K; R(wR2) = 0.193. The molecular structures of 1 – 3 all comprise a central Co atom octahedrally co‐ordinated by the ketonato O atoms of three thd ligands. The transformation between modifications 1 and 2 is of a fully reversible second‐order character. Modifications 1 and 3 are, on the other hand, related by a quasi‐reversible cycle. Heat treatment (specifically sublimation) of 1 leads to 3 whereas re‐crystallization or prolonged storage at room temperature is required to regenerate 1 . Co(thd)₃ has sufficient thermal stability to permit sublimation without degradation. The various forms of Co(thd)₃ are all diamagnetic, viz. a confirmation of the Co^III valence state.     

Strukturchemische und magnetische Untersuchungen an Ho3+‐β″‐Al2O3(Ho0, 5Mg0, 5Al10, 5O17)

Structural Chemistry and Magnetic Properties of Ho³⁺‐β″‐Al₂O₃(Ho_{0, 5}Mg_{0, 5}Al_{10, 5}O₁₇) The crystal structure of Ho³⁺‐β″‐Al₂O₃(Ho_{0, 5}Mg_{0, 5}Al_{10, 5}O₁₇) was determined by single crystal X‐ray diffraction methods at room temperature (trigonal, R3¯m, Z = 3, a = 561.43(12) pm, c = 3353.7(11) pm). The structural chemical results are correlated with magnetic measurements, where ligand field calculations applying the angular overlap model have been taken into account.     

Synthese und Molekülstruktur von [{Cp′(μ‐η1 : η5‐C5H3Me)Mo(μ‐AlRH)}2] (Cp′ = C5H4Me,R = iBu,Et)

Synthesis and Molecular Structure of [{Cp′(μ‐η¹ : η⁵‐C₅H₃Me)Mo(μ‐AlRH)}₂] (Cp′ = C₅H₄Me, R = ⁱBu, Et) [Cp′₂MoH₂] reacts with HAlR₂ to give [{Cp′(μ‐η¹ : η⁵‐C₅H₃Me)Mo(μ‐AlRH)}₂] (Cp′ = C₅H₄Me, R = ⁱBu ( 1 ), Et ( 2 )). Crystal structure determinations were carried out on [Cp′₂MoH₂] and 1 . 1 exhibits a direct Mo–Al bond (2.636(2) Å).     

Structural Relationships obtained from the Coordination of α‐Picolinamide to the (Iminodiacetato)copper(II) Chelate: Synthesis,Crystal Structure,and Properties of (α‐Picolinamide)(iminodiacetato)copper(II) Dihydrate

The stoichiometric reaction of copper(II) hydroxycarbonate, iminodiacetic acid (H₂IDA = HN(CH₂CO₂H)₂) and α‐picolinamide (pya) in water yields crystalline samples of (α‐picolinamide)(iminodiacetato)copper(II) dihydrate, [Cu(IDA)(pya)] · 2 H₂O ( 1 ). The compound was characterised by thermal (TG analysis with FT‐IR study of the evolved gasses), spectral (IR, electronic and ESR spectra), magnetic and single crystal X‐ray diffraction methods. It crystallises in the triclinic system, space group P1, a = 8.8737(4), b = 10.23203(5), c = 15.7167(11) Å, α = 77.61(1)°, β = 103.89(1)°, γ = 80.32(1)°, Z = 4, final R1 = 0.056. The asymmetric unit contains two crystallographic independent molecules but chemically very similar ones. The Cu^II atom exhibits a square base pyramidal coordination (type 4 + 1). pya acts as N,O‐bidentate ligand supplying two among the four closest donor atoms of the metal [averaged bond distances (Å): Cu–N = 1.982(2), Cu–O(amide) = 1.972(2)]. IDA plays a N,O,O′‐terdentate chelating role [averaged bond distances (Å): Cu–N = 2.004(3), Cu–O = 1.941(2) and Cu–O = 2.242(2)]. The coordinating behaviour of pya in 1 is discussed on the basis of its N,O‐bidentate chelating role and the preference of the ‘Cu‐iminodiacetato' moiety [Cu(IDA)] to link the N‐heterocyclic donor of pya in trans versus the Cu–N(IDA) bond. Consistently the ligand pya is able to impose a fac‐chelating configuration to IDA one around the copper(II) as previously has been reported to mixed‐ligand complexes having a 1/1/2 Cu^II/IDA/N(heterocyclic) donor ratio or a closely related 1/1/1/1 Cu^II/IDA/N(heterocyclic)/N(aliphatic) one.     

Synthesis and Crystal Structure of the Fluoride‐Rich Rubidium Scandium Fluoride Oxosilicate Rb3Sc2F5Si4O10

The new quinary fluoride‐rich rubidium scandium oxosilicate Rb₃Sc₂F₅Si₄O₁₀ was obtained from mixtures of RbF, ScF₃, Sc₂O₃ and SiO₂ in sealed platinum ampoules after seventeen days at 700 °C. The colourless compound crystallises orthorhombically in space group Pnma with a = 962.13(5), b = 825.28(4), c = 1838.76(9) pm and Z = 4. For the oxosilicate partial structure, [SiO₄]^4– tetrahedra are connected in (001) by vertex‐sharing to form corrugated unbranched vierer single layers ${2}\atop{{\infty}}$ {[Si₄O₁₀]^4–} (d(Si–O) = 158–165 pm, ∠(O–Si–O) = 103–114°, ∠(Si–O–Si) = 125–145°) containing six‐membered rings. Similar oxosilicate layers with 6³‐net topology are well‐known for the mineral group of micas or in sanbornite Ba₂Si₄O₁₀. Regarding other systems, identical tetrahedral layers can be found in the synthetic borophosphate Mg(H₂O)₂[B₂P₂O₈(OH)₂] · H₂O. The Sc³⁺ cations are coordinated octahedrally by four F^– and two O^2– anions. These cis‐[ScF₄O₂]^5– octahedra (d(Sc–F) = 200–208 pm, d(Sc–O) = 202–205 pm) share one equatorial and two apical F^– anions with others to build up slightly corrugated ${1}\atop{{\infty}}$ {[Sc₂F${t}\atop{2/1}$ F${v}\atop{6/2}$ O${t}\atop{4/1}$ ]^7–} double chains along [010]. These are linked with the oxosilicate layers via two oxygen vertices to construct a three‐dimensional framework with cavities apt to host the three crystallographically independent Rb⁺ cations with coordination numbers of eleven, twelve and thirteen.     

Synthesis,Characterization and Oxide Ionic Conductivity of Binary β‐(Bi2O3)1‐x(Lu2O3)x System

In this research, the effects of doping Lu₂O₃ to α‐Bi₂O₃ in the range of 0.01 < x < 0.10 in a series of different mole fractions (1% < n < 10% mole ratios) was studied. Beside, heat treatment was performed by applying a cascade temperature rise in the range of 700‐800 °C for 72 hours and new phases were obtained in the (Bi₂O₃)_1‐x(Lu₂O₃)_x system. After heat treatment for 72 hours at 800 °C; mixtures, containing 2‐8% mole Lu₂O₃, formed a tetragonal phase. As a result of subjecting mixtures, containing 9% and 10% mole Lu₂O₃, to a quenching process at 825 °C, tetragonal phases were obtained. With the help of XRD, the crystal systems and lattice parameters of the solid solutions were obtained and their characterization was carried out. Thermal measurements were made by using a simultaneous DTA/TG system. The total conductivity (σ_T) in the β‐Bi₂O₃ doped with Lu₂O₃ was measured using the four‐probe DC method.     

ChemInform Abstract: Crystal Growth,Crystal Structure of New Polymorphic Modification, β‐Bi2B8O15 and Thermal Expansion of α‐Bi2B8O15.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Symmetry‐Breaking Transitions in SmCu1+δAs2—χPχ(δ = 0 — 0.2, χ = 0 — 2). Effect of P and Additional Cu Atoms on Crystal Structures and Magnetic Properties

Crystal structures of the compounds SmCu_1+δAs_2—χP_χ (δ = 0 — 0.2, χ = 0 — 2) undergoing symmetry‐breaking transitions and SmCuP_2.3 have been investigated by the X‐ray single crystal and powder methods. While the phases SmCuAs₂ through SmCuAs_1.22P_0.78 retain the tetragonal HfCuSi₂ structure (P4/nmm space group), the compounds SmCuAs_1.11P_0.89 through SmCuAs_0.56P_1.44 adopt the GdCuAs_1.15P_0.85—type structure (Pmmn space group), an orthorhombic variant of the HfCuSi₂‐type. Further distortion follows in SmCuAs_0.33P_1.67 through SmCuP_2.3, the powder patterns of which were indexed in the P2/n space group (P2/c in a standard setting). According to Landau theory the transitions from tetragonal SmCuAs_1.22P_0.78 to orthorhombic SmCuAs_1.11P_0.89 and from orthorhombic SmCuAs_0.56P_1.44 to monoclinic SmCuAs_0.33P_1.67 can be continuous. Introducing extra copper into some of the orthorhombic arsenophosphides restabilizes tetragonal phases (0 < δ ≤ 0.2) with the P4/nmm symmetry, and the reverse transition Pmmn → P4/nmmcan be continuous. Inserting copper atoms into monoclinic SmCuP₂ yields the SmCu_1+δP₂ phosphides with Cmmm symmetry, and this transition is first‐order. Single crystals of SmCu_1.05As_1.67P_0.33, SmCu_1.07As_0.85P_1.15 and SmCu_1.15P₂ have been prepared using iodine as a mineralizing agent. Their structures have partially occupied Cu sites around the square As/P or P layers and they are a stuffed variant of the HfCuSi₂ structure for SmCu_1.05As_1.67P_0.33 (P4/nmm, a = 3.9163(6), c = 9.932(2)Å), a stuffed GdCuAs_1.15P_0.85 structure for SmCu_1.07As_0.85P_1.15 (Pmmn, a = 3.859(1), b = 3.862(1), c = 9.852(3)Å) and a CeCu_1.12P_1.97‐type structure for SmCu_1.15P₂ (Cmmm, a = 5.453(3), b = 19.511(10), c = 5.439(3)Å). The P net in SmCu_1.15P₂ is broken into rectangular units. The results of magnetic measurements for SmCuAsP are reported.     

Syntheses,Crystal Structures,and Vibrational Properties of Two Lead Azide Halides PbN3X (X = Cl,Br)

Abstract: Two new lead azide halides, PbN₃X (X = Cl, Br), were precipitated from aqueous solutions and structurally analyzed by both X-ray single-crystal/powder diffraction and vibrational spectroscopy, in addition to density-functional theory calculations. PbN₃Cl crystallizes in the monoclinic space group P2₁/m (no. 11) with a = 5.5039(11), b = 4.3270(9), c = 7.6576(15) Å, β = 101.28(3)° and adopts a structure with alternating layers of cations and anions. PbN₃Br crystallizes in the orthorhombic space group Pnma (no. 62) with a = 7.9192(2), b = 4.2645(1), c = 11.1396(3) Å, and the cations and anions are alternating crosswise. Within PbN₃Cl, a Pb²⁺ cation is surrounded by five azide and four chloride anions whereas, in PbN₃Br, the coordination consists of five azide and three bromide anions. Both structures contain chain-like [Pb₂X₂]²⁺ units with Pb–Cl = 2.95–3.21 Å and Pb–Br = 3.03–3.38 Å, and the N₃^– dumbbell is capped by five Pb²⁺ with Pb–N = 2.79–2.91 Å in PbN₃Cl and with Pb–N = 2.69–2.89 Å in PbN₃Br. The infrared and Raman spectra show the typical frequencies of a slightly asymmetric N₃^– unit, in good agreement with DFT phonon calculation. Thermal analyses reveal PbN₃Cl to be stable up to 290 °C before it explodes to yield PbCl₂, metallic Pb, and gaseous N₂.