Partial Sn‐atom ordering in Sm3Ga0.80–2.48Sn4.20–2.52

Trisamarium digallide tristannide crystallizes with a partially ordered Pu₃Pd₅‐type structure in space group Cmcm. In a single crystal of Sm₃Ga_1.89(4)Sn_3.11(4), the 8g position is mostly occupied by Sn atoms (93% Sn and 7% Ga), while the 4c and 8f positions are occupied by a Ga/Sn statistical mixture. The evolution of the structure as a function of the Ga content has been studied by X‐ray powder diffraction on ten Sm₃Ga_5−xSn_x samples. It is shown that the 8g position remains occupied essentially exclusively by Sn atoms within the whole homogeneity range, with x ranging from 2.52 to 4.20.     

The Ternary Stannides MgRuSn4 and MgxRh3Sn7—x (x = 0.98—1.55)

The magnesium transition metal stannides MgRuSn₄ and Mg_xRh₃Sn_7—x (x = 0.98—1.55) were synthesized from the elements in glassy carbon crucibles in a water‐cooled sample chamber of a high‐frequency furnace. They were characterized by X‐ray diffraction on powders and single crystals. MgRuSn₄ adopts an ordered PdGa₅ type structure: I4/mcm, a = 674.7(1), c = 1118.1(2) pm, wR2 = 0.0506, 515 F² values and 12 variable parameters. The ruthenium atoms have a square‐antiprismatic tin coordination with Ru—Sn distances of 284 pm. These [RuSn_8/2] antiprisms are condensed via common faces forming two‐dimensional networks. The magnesium atoms fill square‐prismatic cavities between adjacent [RuSn₄] layers with Mg—Sn distances of 299 pm. The rhodium based stannides Mg_xRh₃Sn_7—x crystallize with the cubic Ir₃Ge₇ type structure, space groupe Im3m. The structures of four single crystals with x = 0.98, 1.17, 1.36, and 1.55 have been refined from X‐ray diffractometer data. With increasing tin substitution the a lattice parameter decreases from 932.3(1) pm for x = 0.98 to 929.49(6) pm for x = 1.55. The rhodium atoms have a square antiprismatic tin/magnesium coordination. Mixed Sn/Mg occupancies have been observed for both tin sites but to a larger extend for the 12d Sn2 site. Chemical bonding in MgRuSn₄ and Mg_xRh₃Sn_7—x is briefly discussed.     

Neue Zinn‐reiche Stannide der Systeme AII‐Al‐Sn (AII = Ca,Sr, Ba)

New Tin‐rich Stannides of the Systems A^II‐Al‐Sn (A^II = Ca, Sr, Ba) Four new tin‐rich intermetallics of the ternary systems Ca/Sr/Ba‐Al‐Sn were synthesized from stoichiometric amounts of the elements at maximum temperatures of 1200 °C. Their crystal structures, representing two new types, have been determined using single crystal x‐ray diffraction. Close to the 1:1 composition, the structures of the two isotypic compounds A₁₈[Al₄(Al/Sn)₂Sn₄][Sn₄][Sn]₂ (overall composition A₉M₈; A = Sr/Ba, tetragonal, space group P4/mbm, a = 1325.9(1)/1378.6(1), c = 1272.8(2)/1305.4(1) pm, Z = 4, R1 = 0.0430/0.0293) contain three different anionic Sn/Al building units: Isolated Sn atoms (motif I) coordinated by the alkaline earth cations only (comparable to Ca₂Sn), linear Sn chains (II), which are comparable to the anions in trielides related to the W₅Si₃ structure type and finally octahedral clusters [Al₄M₂Sn₄] (III), composed of four Al atoms forming the center plane, two statistically occupied Al/Sn atoms at the apexes and four exohedral Sn attached to Al. Close to the AM₂ composition, two isotypic tin‐rich intermetallics A₉[Al₃Sn₂][(Sn/Al)₄]Sn₆ (overall composition A₉M₁₅; A = Ca/Sr; space group C2/m, a = 2175.2(1)/2231.0(2), b = 1210.8(1)/1247.0(1), c = 1007.4(1)/1042.0(2) pm, β = 103.38(1)/103.42(1)°, Z = 2, R1 = 0.0541/0.0378) are formed. Their structure is best described as a complex three‐dimensional network, that can be considered to consist of the building units of the binary border phases too, i.e. linear zig‐zag chains of Sn (motif I) like in CaSn, ladders of four‐bonded Sn/Al atoms (II) like in SrAl₂ and trigonal‐bipyramidal clusters [Al₃Sn₂] (III) also present in Ba₃Al₅. Despite the complex structures, some statistically occupied Al/Sn positions and the small disorder of one building unit, the bonding in both structure types can be interpreted using the Zintl concept and Wade's electron counting rules when taking partial Sn‐Sn bonds into account.     

Transmetallierung von Zinn(II) in [Sn(μ3‐PSitBu3)]4 durch Barium – von Sn4P4‐Heterocuban‐Strukturen zu heterobinuklearen Käfigverbindungen mit einem zentralen BanSn4−nP4‐Heterocuban‐Polyeder (n = 1, 2 und 3)

Transmetallation of Tin(II) in [Sn(μ₃‐PSitBu₃)]₄ by Barium – from Sn₄P₄ Heterocubane Structures to Heterobinuclear Cage Compounds with a Central Ba_nSn_4?nP₄ Heterocubane Polyhedron (n = 1, 2 and 3) For the preparation of compounds of the type [Ba_nSn_4?n(PSitBu₃)₄] (n = 1 ( 2 ), 2 ( 3 ) and 3 ( 4 )) two synthetic routes are applicable: in the transmetallation reaction homometallic [Sn₄(PSitBu₃)₄] ( 1 ) reacts with barium metal and in a deprotonation reaction (metallation) tri(tert‐butyl)silylphosphane reacts simultaneously with (thf)₂Ba[N(SiMe₃)₂]₂ and Sn[N(SiMe₃)₂]₂. During the transmetallation reaction mixtures of the heterobimetallic cage compounds 2 to 4 are obtained, however, analytically pure compounds 2 and 3 are accessible by the metallation reaction. Compound 4 is formed as a minor product together with 3 . Due to the larger Ba‐P bond lengths compared to the Sn‐P values the substitution of tin by barium leads to strong distortions of the heterocubane moiety. With NMR‐spectroscopic experiments one could show that all the above mentioned compounds form Ba_nSn_4?nP₄ heterocubane cage structures.     

Substitution Effects in Zintl Phases: Synthesis and Crystal Structure of the Novel Phases Ae3Sn4−xBi1+x (x ≤ 1; Ae = Sr,Ba) Containing Shubnikov‐Type Nets $^{2}_{\infty}\rm [Sn_{4-x}Bi_{x}]$

The compounds Ae₃Sn_4?xBi_1+x (Ae = Sr, Ba) with x < 1 have been synthesized by solid‐state reactions in welded Nb tubes at high temperature. Their structures were determined by single crystal X‐ray diffraction studies to be tetragonal; space group I4/mcm (No. 140); Z = 4, with a = 8.968(1) Å, c = 12.859(1) Å for Sr₃Sn_3.36Bi_1.64(3) ( 1 ) and a = 9.248(2), c = 13.323(3) Å for Ba₃Sn_3.16Bi_1.84(3) ( 2 ). The structure consists of two interpenetrating networks formed by a 3D Ae_6/2Bi substructure (anti‐ReO₃ type) forming the host, and layers of interconnected four‐member units [Sn_4?xBi_x] with “butterfly”‐like shape as the guest. According to the Zintl‐Klemm concept, the compounds are slightly electron deficient and will be charge balanced for x = 1. The electronic structures of Ae₃Sn_4?xBi_1+x calculated by the TB‐LMTO‐ASA method indicate that the compounds correspond to ideal semiconducting Zintl phases with a narrow band gap for x = 1 (zero‐gap semiconductor). The origin of the slight deviation from the optimal electron count for a valance compound is discussed.     

Synthesis and structural characterization of the type‐I clathrates K8AlxSn46–x and Rb8AlxSn46–x (x ≃ 6.4–9.7)

Exploratory studies in the systems A–Al–Sn (A = K and Rb) yielded the clathrates K₈Al_xSn_46–x (potassium aluminium stannide) and Rb₈Al_xSn_46–x (rubidium aluminium stannide), both with the cubic type‐I structure (space group Pmn, No. 223; a ? 12.0 Å). The Al:Sn ratio is close to the idealized A₈Al₈Sn₃₈ composition and it is shown that it can be varied slightly, in the range of ca ±1.5, depending on the experimental conditions. Both the (Sn,Al)₂₀ and the (Sn,Al)₂₄ cages in the structure are fully occupied by the guest alkali metal atoms, i.e. K or Rb. The A₈Al₈Sn₃₈ formula has a valence electron count that obeys the valence rules and represents an intrinsic semiconductor, while the experimentally determined compositions A₈Al_8±xSn_38?x suggest the synthesized materials to be nearly charge‐balanced Zintl phases, i.e. they are likely to behave as heavily doped p‐ or n‐type semiconductors.     

Endohedrally Filled [Ni@Sn9]4− and [Co@Sn9]5− Clusters in the Neat Solids Na12Ni1−xSn17 and K13−xCo1−xSn17: Crystal Structure and 119Sn Solid‐State NMR Spectroscopy

A systematic approach to the formation of endohedrally filled atom clusters by a high‐temperature route instead of the more frequent multistep syntheses in solution is presented. Zintl phases Na₁₂Ni_1?xSn₁₇ and K_13?xCo_1?xSn₁₇, containing endohedrally filled intermetalloid clusters [Ni@Sn₉]^4? or [Co@Sn₉]^5? beside [Sn₄]^4?, are obtained from high‐temperature reactions. The arrangement of [Ni@Sn₉]^4? or [Co@Sn₉]^5? and [Sn₄]^4? clusters, which are present in the ratio 1:2, can be regarded as a hierarchical replacement variant of the hexagonal Laves phase MgZn₂ on the Mg and Zn positions, respectively. The alkali‐metal positions are considered for the first time in the hierarchical relationship, which leads to a comprehensive topological parallel and a better understanding of the composition of these compounds. The positions of the alkali‐metal atoms in the title compounds are related to the known inclusion of hydrogen atoms in the voids of Laves phases. The inclusion of Co atoms in the {Sn₉} cages correlates strongly with the number of K vacancies in K_13?xCo_1?xSn₁₇ and K_5?xCo_1?xSn₉, and consequently, all compounds correspond to diamagnetic valence compounds. Owing to their diamagnetism, K_13?xCo_1?xSn₁₇, and K_5?xCo_1?xSn₉, as well as the d‐block metal free binary compounds K₁₂Sn₁₇ and K₄Sn₉, were characterized for the first time by ¹¹⁹Sn solid‐state NMR spectroscopy.     

Bromo­di­methyl(N‐methyl­pyrrolidin‐2‐one‐O)­tin(IV)‐di‐μ‐bromo‐bromo­di­methyl­tin(IV)

The preparation and X‐ray analysis of the title compound, [Sn₂Br₄(CH₃)₄(C₅H₉NO)], are described. The compound contains two Sn atoms in the asymmetric unit, that complexed by N‐methyl­pyrrolidin‐2‐one being hexacoordinated (a), the other exhibiting pentacoordination (b). The most important features are three different Sn—Br bond lengths at both Sn atoms with the following values: (a) 2.5060 (9), 2.7152 (10) and 3.7118 (10) Å; (b) 2.5084 (10), 2.5279 (9) and 3.5841 (10) Å.     

Tetrapotassium nonastannide,K4Sn9

In K₄Sn₉, which crystallizes with a new structure type, the Sn atoms form isolated Wade nido‐[Sn₉]^4? clusters of approxi­mate C_4v symmetry (monocapped square antiprisms), with Sn—Sn distances ranging from 2.9264 (9) to 3.348 (1) Å. The cluster anions are separated by K⁺ cations and are in a hexagonal close‐packed arrangement.     

Phasenbeziehungen im System LiGa?Sn und die Kristallstrukturen der intermediären Phasen LiGaSn und Li2Ga2Sn

Phase Relations in the System LiGa? Sn and the Crystal Structures of the Intermediate Compounds LiGaSn and Li₂Ga₂Sn The quasibinary system LiGa? Sn contains the intermediate ternary phases Li₇Ga₇Sn₃, Li₂Ga₂Sn, Li₅Ga₅Sn₃, Li₃Ga₃Sn₂ and LiGaSn. Single crystals of LiGaSn (a = 632.9(4) pm, Fd3m, Z = 4), Li₃Ga₃Sn₂ (a = 445.4(3), c = 1 090.0(2) pm, hP*), Li₅Ga₅Sn₃ (a = 447.0(4), c = 4 220.0(9) pm, hP*) and Li₂Ga₂Sn (a = 441.1(2), c = 2 164.5(7) pm, P6₃/mmc, Z = 4) have been grown from the melt. The crystal structures of LiGaSn and Li₂Ga₂Sn have been determined by single crystal X-ray methods (R = 0.029 bzw. 0.107 respectively). The crystal structure of LiGaSn contains a sphalerite-type Ga/Sn-arrangement, the Ga/Sn-arrangement of Li₂Ga₂Sn corresponds to a stacking variant of the wurtzite- and sphalerite-type. The compounds can be classified in terms of the Zintl concept.     

Phase Width and Site Preferences in the EuMgxGa4−x Series

A series of EuMg_xGa_4?x compounds were synthesized using high temperature, solid‐state methods and characterized by both powder and single crystal X‐ray diffraction. All compounds crystallize in the tetragonal BaAl₄‐type structure (space group I4/mmm, Z = 2, Pearson symbol tI10) with full occupancy of Ga at the apical atom (4e) site and mixed‐occupancy of Mg and Ga at the basal atom (4d) site. Six compositions were analyzed by single crystal X‐ray diffraction: EuMg_0.21(1)Ga_3.79(1), EuMg_0.91(1)Ga_3.09(1), EuMg_1.22(1)Ga_2.78(1), EuMg_1.78(1)Ga_2.22(1), EuMg_1.84(1)Ga_2.16(1), and EuMg_1.94(1)Ga_2.06(1). As the larger Mg atoms increasingly replace Ga atoms at the basal site in EuMg_xGa_4?x, the a‐axis lengths at first decrease and then increase, while the c‐axis lengths increase monotonically along the series. The phase width of the BaAl₄‐type EuMg_xGa_4?x series is identified to be 0 ≤ x ≤ 1.94(1), a range which corresponds to 12.06(1)‐14 valence electrons per formula unit, and can be understood by their electronic structures using density of states (DOS) curves calculated by tight‐binding calculations. Mg substitution for Ga at the basal site is consistent with the site preferences for mixed metals on the three‐dimensional framework of the BaAl₄‐structure based on both electronegativities and sizes, and provides the rationale for the unusual behavior in lattice parameters. The observed site preference was also rationalized by total electronic energies calculated for two different coloring schemes.     

Darstellung und Kristallstruktur von ANi10P3 (A: Zn,Ga, Sn,Sb)

Preparation and Crystal Structure of A Ni₁₀P₃ ( A : Zn, Ga, Sn, Sb) Four compounds ANi₁₀P₃ (A: Zn, Ga, Sn, Sb) were prepared by heating mixtures of the elements and investigated by means of X‐ray methods. Single crystal structure determinations of ZnNi₁₀P₃ (a = 7.665(1), c = 9.360(1) Å) and SnNi₁₀P₃ (a = 7.674(1), c = 9.621(1) Å) respectively showed, that they are isotypic and crystallize in a new structure (P3m1; Z = 3). This type is characterized by 3²⁰ and 3²⁴ cages of Ni atoms (Frank Kasper polyhedra), which are connected with each other. A atoms are located in the centres of these polyhedra and have no direct bonds to the P atoms.     

Synthesis,Spectroscopic, and X‐Ray Diffraction Studies of cis‐Dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl3 H‐pyrazol‐3‐onato) Tin(IV)

Reaction between an aqueous ethanol solution of tin(II) chloride and that of 4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐one in the presence of O₂ gave the compound cis‐dichlorobis(4‐propanoyl‐2,4‐dihydro‐5‐methyl‐2‐phenyl‐3 H‐pyrazol‐3‐onato) tin(IV) [(C₂₆H₂₆N₄O₄)SnCl₂]. The compound has a six‐coordinated Sn^IV centre in a distorted octahedral configuration with two chloro ligands in cis position. The tin atom is also at a pseudo two‐fold axis of inversion for both the ligand anions and the two cis‐chloro ligands. The orange compound crystallizes in the triclinic space group P 1 with unit cell dimensions, a = 8.741(3) Å, b = 12.325(7) Å, c = 13.922(7) Å; α = 71.59(4), β = 79.39(3), γ = 75.18(4); Z = 2 and D_x = 1.575 g cm^–3. The important bond distances in the chelate ring are Sn–O [2.041 to 2.103 Å], Sn–Cl [2.347 to 2.351 Å], C–O [1.261 to 1.289 Å] and C–C [1.401 Å] the bond angles are O–Sn–O 82.6 to 87.7° and Cl–Sn–Cl 97.59°. The UV, IR, ¹H NMR and ¹¹⁹Sn Mössbauer spectral data of the compound are reported and discussed.     

The [Sn5]2– Cluster Compound [K‐(2,2,2‐crypt)]2Sn5 – Synthesis,Crystal Structure,Raman Spectrum,and Hierarchical Relationship to CaIn2

Dark red crystals of [K‐(2,2,2)‐crypt)]₂Sn₅ precipitate after the reaction of (2,2,2)‐crypt with a solution of K_1.33Sn in liquid ammonia at room temperature. The compound is sensitive to oxidation and hydrolysis. The sequence of Raman bands (104, 120, 133 and 180 cm^–1) is characteristic for the trigonal bipyramidal closo‐[Sn₅]^2– cluster anion. The wave numbers correspond with the data from Hartree‐Fock calculations (114, 128, 142 and 187 cm^–1). The compound crystallizes trigonally (a = 11.736 Å, c = 22.117 Å, Z = 2, space group P3c1 (No. 165); Pearson code hP262), isotypic with [Na‐(2,2,2)‐crypt)]₂Pb₅. The atoms of the cluster show strange anisotropic displacements, which are perfectly reducible to a helical rigid‐body motion around and along [001] (libration: ± 9.5°; translation ± 0.29 Å). The structure can be described as a hierarchical derivative of the initiator CaIn₂ (P6₃/mmc, hP6), generated by an atom‐to‐aggregate replacement: [Ca][In]₂ = [Sn₅][K @ C₃₆H₇₂N₄O₁₂]₂. Thus, the distribution of the [Sn₅]^2– Zintl anions is hexagonal primitive, and the cation complexes are located close to the centers of trigonal superprisms formed by Sn₅ clusters.     

Synthese und Kristallstrukturen von α‐ und β‐Ba3(PS4)2 sowie von Ba3(PSe4)2

Synthesis and Crystal Structures of α‐, β‐Ba₃(PS₄)₂ and Ba₃(PSe₄)₂ Ba₃(PS₄)₂ and Ba₃(PSe₄)₂ were prepared by heating mixtures of the elements at 800 °C for 25 h. Both compounds were investigated by single crystal X‐ray methods. The thiophosphate is dimorphic and undergoes a displacive phase transition at about 75 °C. Both modifications crystallize in new structure types. In the room temperature phase (α‐Ba₃(PS₄)₂: P2₁/a; a = 11.649(3), b = 6.610(1), c = 17.299(2) Å, β = 90.26(3)°; Z = 4) three crystallographically independent Ba atoms are surrounded by ten sulfur atoms forming distorted polyhedra. The arrangement of the PS₄ tetrahedra, isolated from each other, is comparable with the formation of the SO₄^2? ions of β‐K₂SO₄. In β‐Ba₃(PS₄)₂ (C2/m; a = 11.597(2), b = 6.727(1), c = 8.704(2) Å; β = 90.00(3)°; Z = 2) the PS₄ tetrahedra are no more tilted along [001], but oriented parallel to each other inducing less distorted tetrahedra and polyhedra around the Ba atoms, respectively. Ba₃(PSe₄)₂ (P2₁/a; a = 12.282(2), b = 6.906(1), c = 18.061(4) Å; β = 90.23(3)°; Z = 4) is isotypic to α‐Ba₃(PS₄)₂ and no phase transition could be detected up to about 550 °C.     

Tetra­butyl­bis(N‐phthaloyl­glycinato)­distannoxane dimer

The crystal structure of the title compound, [Sn₄(C₄H₉)₈(C₁₀H₆NO₄)₄O₂], contains centrosymmetric dimers. It contains a central Sn₂O₂ core with the O atoms bonded to two di­butyl­bis(N‐phthaloyl­glycinato)­tin units. The Sn atoms of the core are six‐coordinate in a skew trapezoidal bipyramidal geometry, while the exocyclic Sn atoms are essentially five‐coordinate in a distorted trigonal geometry. The Sn—C distances lie in a narrow range of 2.120 (5)–2.138 (4) Å.     

Ga2Br2R2 und Ga3I2R3 [R = C(SiMe3)3] — zwei neue elementorganische Galliumsubhalogenide mit einer bzw. zwei Ga‐Ga‐Bindungen

Ga₂Br₂R₂ and Ga₃I₂R₃ [R = C(SiMe₃)₃] — Two New Organoelement Subhalides of Gallium Containing One or Two Ga‐Ga Single Bonds The oxidation of the tetrahedral tetragallium cluster Ga₄[C(SiMe₃)₃]₄ ( 1 ) with elemental bromine in the presence of AlBr₃ yielded the corresponding gallium subhalide Ga₂Br₂R₂ [ 4 , R = C(SiMe₃)₃], which remains monomer even in the solid state and in which the Ga^II atoms are connected by a short Ga‐Ga single bond [243.2(2) pm]. The analogous diiodide Ga₂I₂R₂ ( 3 ), which was obtained on a similar route by our group only recently, did not react with lithium tert‐butanolate by substitution as originally expected. Instead, partial disproportionation occurred with the formation of the trigallium diiodide Ga₃I₂R₃ ( 6 ), in which three Ga atoms are connected by two Ga‐Ga single bonds (255.1 pm on average). Both terminal Ga atoms have a coordination number of four owing to the bridging function of both iodine atoms, while the inner one which has an oxidation number of +1 remains coordinatively unsaturated. An average oxidation state of 1.66 resulted for all atoms of the chain. The Ga^III compound {[GaI(R)(OCMe₃)(OH)]Li}₂ ( 7 ) was isolated as the second product of the disproportionation. It is a dimer in the solid state via Li‐O bridges and shows a hindered rotation of its tert‐butyl group.     

Ba11KX7O2 (X  P,As): Two Novel Zintl Phases with infinite chains of oxygen centered Ba6 octahedra,isolated X3− and dimeric X24− anions

Reactions of “BaX” (X ? P, As) with Ba, K and BaO in tantalum tubes at 900–1000°C yielded black, very air- and moisture-sensitive crystals of Ba₁₁KP₇O₂ and isotypic Ba₁₁KAs₇O₂ which were characterized by EDX and X-ray diffraction (orthorhombic, Fddd, Z = 8; a = 1069.9(1), b = 1514.3(2), c = 3164.6(4) pm and a = 1087.8(2), b = 1542.3(2), c = 3232.4(4) pm, respectively). The structure contains infinite zigzag chains, [Ba₄Ba_2/2O], of oxygen-centered, corner-sharing Ba₆ octahedra along [100]. They are connected by linear strings built of alternating isolated X atoms and X₂ dimers to form layers parallel to (001). While the isolated X atoms are surrounded by eight Ba forming a distorted cube, the X₂ dimers center a Ba₁₂ polyhedron which is comprised of a pair of face-sharing Ba square antiprisms. This results in a cube–antiprism-antiprism-cube sequence of face-sharing Ba polyhedra. Additional X atoms function as spacers between the layers and connect them along [001]. Two atom positions are statistically occupied by Ba and K, and the formula may be written as Ba²⁺₁₁K⁺X^3?₅(X₂)^4?O^2?₂ according to the Zintl-Klemm concept.     

Bis­[tetrakis­(tri­phenyl­phosphine‐κP)silver(I)] di‐μ‐tri­fluoro­acetato‐κ4O:O′‐bis[bis­(tri­fluoro­acetato‐κO)stannate(IV)]

The crystal structure of the title compound, [Ag(C₁₈H₁₅P)₄]₂[Sn₂(CH₃)₄(CF₃CO₂)₆], consists of discrete tetrahedral cations and trans‐C₂SnO₄ octahedral dianions [C—Sn—C = 154.6 (2)°]. The dianion lies about a center of inversion and the two Sn atoms are linked unevenly by the carboxyl­ate unit [Sn—O = 2.291 (3) Å and SnO = 2.818 (3) Å].     

Monoclinic La1−xBaxMnO3 (x = 0.185) at 160 K

Single‐crystal X‐ray diffraction has shown that lanthanum barium manganese trioxide, La_0.815Ba_0.185MnO₃, is monoclinic (I2/c) below a first‐order phase transition at 187.1 (3) K. This result differs from the Pbnm symmetry usually assigned to colossal magnetoresistance oxides, A_1−xA′_xMnO₃ with x≃ 0.2, which adopt a distorted perovskite‐type crystal structure. The Mn atom lies on an inversion center, the disordered Li/Ba site is on a twofold axis and one of the two independent O atoms also lies on a twofold axis.