Darstellung und Kristallstrukturen von Ln2Al3Si2 und Ln2AlSi2 (Ln: Y,Tb–Lu)

Synthesis and Crystal Structures of Ln ₂Al₃Si₂ and Ln ₂AlSi₂ ( Ln : Y, Tb–Lu) Eight new ternary aluminium silicides were prepared by heating mixtures of the elements and investigated by means of single‐crystal X‐ray methods. Tb₂Al₃Si₂ (a = 10.197(2), b = 4.045(1), c = 6.614(2) Å, β = 101.11(2)°) and Dy₂Al₃Si₂ (a = 10.144(6), b = 4.028(3), c = 6.580(6) Å, β = 101.04(6)°) crystallize in the Y₂Al₃Si₂ type structure, which contains wavy layers of Al and Si atoms linked together by additional Al atoms and linear Si–Al–Si bonds. Through this there are channels along [010], which are filled by Tb and Dy atoms respectively. The silicides Ln₂AlSi₂ with Ln = Y (a = 8.663(2), b = 5.748(1), c = 4.050(1) Å), Ho (a = 8.578(2), b = 5.732(1), c = 4.022(1) Å), Er (a = 8.529(2), b = 5.719(2), c = 4.011(1) Å), Tm (a = 8.454(5), b = 5.737(2), c = 3.984(2) Å) and Lu (a = 8.416(2), b = 5.662(2), c = 4.001(1) Å) crystallize in the W₂CoB₂ type structure (Immm; Z = 2), whereas the structure of Yb₂AlSi₂ (a = 6.765(2), c = 4.226(1) Å; P4/mbm; Z = 2) corresponds to a ternary variant of the U₃Si₂ type structure. In all compounds the Si atoms are coordinated by trigonal prisms of metal atoms, which are connected by common faces so that Si₂ pairs (d_Si–Si: 2.37–2.42 Å) are formed.     

Synthesis,Structures, and Properties of Layered Quaternary Chalcogenides of the General Formula ALnEQ4 (A = K,Rb; Ln = Ce,Pr, Eu; E = Si,Ge; Q = S,Se)

Four related quaternary compounds containing rare‐earth metals have been synthesized employing the molten flux method and metathesis. The reactions of Eu and Rb₂S₅ with Si and Ge in evacuated fused silica ampoules at 725 °C for 150 h yielded RbEuSiS₄ ( I ) and RbEuGeS₄ ( II ), respectively. On the other hand, a reaction between CeCl₃ and K₄Ge₄Se₁₀ at 650 °C for 148 h has yielded KCeGeSe₄ ( III ) and KPrSiSe₄( IV ) was obtained by the reaction of elemental Pr, Si and Se in KCl flux at 850 °C for 168 h. Crystal data for these compounds are as follows: I , orthorhombic, space group P2₁2₁2₁ (#19), a = 6.392(1), b = 6.634(2), c = 17.001(3) Å, α = β = γ = 90°, Z = 4; II , monoclinic, space group P2₁/m (#11), a = 6.498(2), b = 6.689(3), c = 8.964(3) Å, β = 108.647(6)°, Z = 2; III , monoclinic, space group P2₁ (#4), a = 6.852(2), b = 7.025(2), c = 9.017(3) Å, β = 108.116(2)°, Z = 2; IV , monoclinic, space group P2₁ (#4), a = 6.736(2), b = 6.943(2), c = 8.990(1) Å, β = 108.262(2)°, Z = 2. The crystal structures of I ‐ IV contain two‐dimensional corrugated anionic layers of the general formula, [LnEQ₄]^? (Ln = Ce, Pr, Eu; E = Si, Ge and Q = S, Se) alternately piled upon layers of alkali cations. In addition to structural elucidation, Raman and UV‐visible spectroscopy, and magnetic measurements for compound III (KCeGeSe₄) are also discussed.     

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.     

ThSi2 Type Ytterbium Disilicide and its Analogues YbTxSi2–x (T = Cr,Fe, Co)

YbSi₂ and the derivatives YbT_xSi_2–x (T = Cr, Fe, Co) crystallizing in the α‐ThSi₂ structure type were obtained as single crystals from reactions run in liquid indium. All silicides were investigated by single‐crystal X‐ray diffraction, I4₁/amd space group and the lattice constants are: a = 3.9868(6) Å and c = 13.541(3) Å for YbSi₂, a = 4.0123(6) Å and c = 13.542(3) Å for YbCr_0.27Si_1.73, a = 4.0142(6) Å and c = 13.830(3) Å for YbCr_0.71Si_1.29, a = 4.0080(6) Å and c = 13.751(3) Å for YbFe_0.34Si_1.66, and a = 4.0036(6) Å, c = 13.707(3) Å for YbCo_0.21Si_1.79. YbSi₂ and YbT_xSi_2–x compounds are polar intermetallics with three‐dimensional Si and M (T+Si) polyanion sub‐networks, respectively, filled with ytterbium atoms. The degree of substitution of transition metal at the silicon site is signficant and leads to changes in the average bond lengths and bond angles substantially.     

Synthese und Kristallstrukturen der Calcium‐Iridiumsilicide Ca3Ir4Si4 und Ca2Ir2Si

Synthesis and Crystal Structures of the Calcium Iridium Silicides Ca₃Ir₄Si₄ and Ca₂Ir₂Si The new compounds Ca₃Ir₄Si₄ und Ca₂Ir₂Si were prepared by reaction of the elemental components in sealed tantalum ampoules at 1200 °C. Their structures were determined from X‐ray single crystal data. Ca₃Ir₄Si₄(cubic, space group I4¯3m, a = 7.4171(2)Å, Z = 2) crystallizes with the Na₃Pt₄Ge₄ type structure. For Ca₂Ir₂Si (monoclinic, space group C2/c, a = 9.6567(5)Å, b = 5.8252(2)Å, c = 7.3019(4)Å, β = 100.212(2)°, Z = 4) a new structure was found. Chains of edge sharing, heavily distorted SiIr₄‐tetrahedra (Ir‐Si: 2.381 and 2.414Å) are connected via short Ir—Ir‐contacts (2.640Å) to form an open Ir/Si‐framework accommodating a three‐dimensional arrangement of calcium atoms (Ca—Ca: 3.413 ‐ 3.948Å).     

Zur Kenntnis der Fluoride zweiwertiger Lanthanoide. III. Neue Fluoroperowskite vom Typ CsLn1−xLn′xF3 und RbLn1−xLn′xF3 mit Ln = Eu2+ bzw. Sm2+ und Ln′ = Yb2+

On Fluorides of Divalent Lanthanoids. III. New Fluoroperovskites of the MLn_1?xLn′_xF₃ Type with M = Cs, Rb; Ln = Eu²⁺, Sm²⁺; Ln′ Yb²⁺ New fluoroperovskites with divalent lanthanoids have been prepared. They are: CsEu_1?xYb_xF₃, yellow, with x = 0.25, a = 4.737(1) Å; x = 0.50, a = 4.696(1) Å; x = 0.75, a = 4.653(1) Å; CsSm_xYb_1?xF₃, violet, with x = 0.25, a = 4.656(1) Å; x = 0.18, a = 4.645(1) Å, the latter mixed with Sm_0.68Yb_0.32F₃, a = 5.781(1) Å; RbEu_xYb_1?xF₃, orange, with x = 0.25, a = 4.573(1) Å; x = 0.23, a = 4.568(1) Å, the latter mixed with Eu_0.94Yb_0.06F₂, a = 5.827(1) Å; RbSm_0.13Yb_0.87F₃, brown, a = 4.555(1) Å.     

Die Tieftemperaturmodifikationen von Ag6Si2O7 und Ag6Ge2O7 – Darstellung,Kristallstruktur und Vergleich der Ag?Ag-Abstände

On the Low Temperature Modifications of Ag₆Si₂O₇ and Ag₆Ge₂O₇ – Synthesis, Crystal Structure, and Comparison of Ag? Ag Distances For the first time, single crystals of Ag₆Si₂O₇ and Ag₆Ge₂O₇ have been obtained by solid state reactions of the binary oxides at temperatures of 350°C while applying oxygen pressures of 700 bar. According to the results of X-ray crystal structure determinations both compounds crystallize isostructural in P2₁ (Ag₆Si₂O₇: a = 5.3043(5) Å, b = 9.7533(7) Å, c = 15.9283(13) Å, β = 91.165(8)°, 3881 independent reflections, R1 = 3.3%, wR2 = 7.2%; Ag₆Ge₂O₇: a = 5.3713(4) Å, b = 9.9835(8) Å, c = 16.2249(14) Å, β = 90.904(8)°, 2111 independent reflections, R1 = 4.3%, wR2 = 6.0%, Z = 4). The crystal structures contain two independent M₂O₇^6? anions, one in a staggered, and the other in an ecliptic conformation. The cationic partial structure may be described as a distorted bcc arrangement of Ag⁺ and M⁴⁺. Comparison of the structures with respect to the Ag? Ag separations reveals the latter to be probably due to intrinsic d¹⁰–d¹⁰ bonding interactions as far as the range of 2.89 Å to 3.25 Å is considered.     

Mg3Ir3Si8, ein neues Magnesium‐Iridium‐Silicid mit Tetraedern und gekappten Tetraedern aus Silicium‐Atomen

Mg₃Ir₃Si₈, a New Magnesium Iridium Silicide with Si₄ Tetrahedra and Si₁₂ Truncated Tetrahedra The ternary silicide Mg₃Ir₃Si₈ (cubic, a = 1221.4(1) pm, space group , 8 formula units per unit cell) was prepared by reaction of the elemental components in a sealed molybdenum container (1000 °C, 1 d, cooled with 100 °/h). The crystal structure was determined from single crystal data. Short distances in the three‐dimensional iridium silicon network indicate strong Ir‐Si‐bonding (d(Ir‐Si) = 240.5(2) and 245.6(1) pm). In addition, homonuclear bonding seems to be important, resulting in the formation of Si₄‐tetrahedra (d(Si‐Si) = 257(1) pm), and Mg centered Si₁₂‐polyhedra with the shape of truncated tetrahedra (d(Si‐Si) = 241(1) and 261.0(9) pm). Furthermore, Mg₄‐tetrahedra with Mg‐Mg‐distances of 355(2) pm are formed. The structure may be derived from the structure of the isotypic compounds Mg₅Pd₁₀Si₁₆ and Mg₅Pt₁₀Si₁₆ by adding a Mg siteset and subtracting a platinum metal siteset. It can be described by an expanded cubic “close” packing of MgIr₆‐octahedra in which Si₄‐tetrahedra reside in the octahedral holes while Mg₄‐tetrahedra and MgSi₁₂‐units occupy one half of the tetrahedral holes each.     

New Examples for the Unexpected Stability of the 10π‐Electron Hückel Arene [Si6]10–

The compounds Ba₄Ag₂Si₆, Eu₄Ag₂Si₆, and Ca₄Ag₂Si₆, prepared from the elements at 1273 K (the components in inner corundum crucibles are enclosed in sealed quartz ampoules), are brittle semiconductors with silvery luster. They react slowly with acids liberating hydrogen. Ba₄Ag₂[Si₆] and Eu₄Ag₂[Si₆] crystallize like Ba₄Li₂[Si₆] (space group Fddd (No. 70); a = 8.613 Å, b = 14.927 Å, c = 19.639 Å, and a = 8.420 Å, b = 14.585 Å, c = 17.864 Å, respectively), whereas Ca₄Ag₂[Si₆] represents a new structure type (space group Fmmm (No. 69); a = 8.315 Å, b = 14.391 Å, c = 8.646 Å). The three compounds are Zintl phases with the formal charges M²⁺, Ag⁺ and [Si₆]^10–. The mean bond lengths d(Si–Si) = 2.335–2.381 Å in the 10π‐Hückel arene [Si₆]^10– as well as d(Ag–Si) = 2.464–2.595 Å vary with the size of the M²⁺ cations. The chemical bonding was analyzed in terms of the Electron Localization Function (ELF) and compared with the bonding in related systems (Ce₄Co₂Si₆).     

Zur Kenntnis der inversen Perowskite M3TO (M = Ca,Sr, Yb; T = Si,Ge, Sn,Pb)

On the Inverse Perovskites M₃TO (M = Ca, Sr, Yb; T = Si, Ge, Sn, Pb) Ca₃SiO and seven further inverse perovskites M₃TO (M = Ca, Sr, Yb; T = Si, Ge, Sn, Pb) were prepared in iron crucibles under argon by the reactions 6 M + TO₂ + T = 2 M₃TO, and 3 M+ TO = M₃TO for Yb₃PbO, respectively, at temperatures between 1123 to 1173 K. The crystal structures of all compounds were solved and refined using X—ray powder diffraction methods. Ca₃SiO, Ca₃GeO, Sr₃SiO, Sr₃GeO, Yb₃SiO and Yb₃GeO are orthorhombic perovskites (anti—GdFeO₃—type, space group Pbnm, No. 62, Z = 4). They show slightly distorted corner—sharing OM₆ octahedra that are tilted with respect to their positions in the ideal perovskite structure. The effective radii of the T^4— vary significantly with M²⁺. Thus, these perovskites can no longer be discussed in terms of the hard—sphere model, and Goldschmidt's tolerance factor does not apply. The ideal cubic representatives Yb₃SnO and Yb₃PbO were refined in space group Pm3¯m (anti—SrTiO₃ type, Z = 1).     

Kristallstrukturen aus CaBe2Ge2‐ und CeMg2Si2‐analogen Blöcken: Die Phosphide LnPt2P2−x (Ln: La,Sm)

Crystal Structures of CaBe₂Ge₂ and CeMg₂Si₂ analogous Units: The Phosphides LnPt₂P_2?x (Ln: La, Sm) Single crystals of LaPt₂P_1.44 (a = 4.174(1), c = 19.212(5) Å) were grown by reaction of vaporous phosphorus with LaPt₂ at 1050 °C during two weeks, whereas SmPt₂P_1.50 (a = 4.131(1), c = 19.086(4) Å) was synthesized by heating mixtures of the elements at 900 and 1100 °C (60 h) and annealing at 1050 °C (300 h). Both phosphides were investigated by single crystal X‐ray methods. Their crystal structures (I4/mmm; Z = 4) consist of CaBe₂Ge₂ and CeMg₂Si₂ analogous units alternating with each other along [001]. The positions of the P1 atoms are occupied incompletely causing the deviation to the 1:2:2 stoichiometry. Another compounds LnPt₂P_2?x were studied by X‐ray powder diffraction resulting in the following lattice constants: a = 4.150(1), c = 19.132(5) Å for CePt₂P_2–x, a = 4.137(1), c = 19.085(4) Å for PrPt₂P_2?x, and a = 4.127(1), c = 19.040(2) Å for NdPt₂P_2?x.     

ACu9X4 ‐ Neue Verbindungen mit der CeNi8, 5Si4, 5‐Struktur (A: Sr,Ba; X: Si,Ge)

ACu₉X₄ ‐ New Compounds with CeNi_{8, 5}Si_{4, 5} Structure (A: Sr, Ba; X: Si, Ge) The new compounds SrCu₉Si₄ (a = 8.146(1), c = 11.629(2)Å), BaCu₉Si₄ (a = 8.198(2), c = 11.735(2)Å), SrCu₉Ge₄ (a = 8.273(2), c = 11.909(5)Å), and BaCu₉Ge₄ (a = 8.338(4), c = 12.011(7)Å) are formed by reaction of the elements at 1000° ‐ 1100 °C. They are isotypic (I4/mcm, Z = 4) and crystallize in an ordered variant of the cubic NaZn₁₃ type structure, also built up by the binary phase BaCu₁₃. In the ternary compounds the positions of Cu2 are orderly occupied by copper and silicon and germanium, respectively. This results in a lowering of symmetry and a distortion of the polyhedra. The metallic conductivity of the compounds was confirmed by measurements on BaCu₉Si₄.     

Über den H‐ und A‐Typ von La2[Si2O7]

On the H‐ and A‐Type Structure of La₂[Si₂O₇] By thermal decomposition of La₃F₃[Si₃O₉] at 700 °C in a CsCl flux single crystals of a new form of La₂[Si₂O₇] have been found which is called H type (triclinic, P1; a = 681.13(4), b = 686.64(4), c = 1250.23(8) pm, α = 82.529(7), β = 88.027(6), γ = 88.959(6)°; V_m = 87.223(9) cm³/mol, D_x = 5.113(8) g/cm³, Z = 4) continuing Felsche's nomenclature. It crystallizes isotypically to the triclinic K₂[Cr₂O₇] in a structure closely related to that of A–La₂[Si₂O₇] (tetragonal, P4₁; a = 683.83(7), c = 2473.6(4) pm; V_m = 87.072(9) cm³/mol, D_x = 5.122(8) g/cm³, Z = 8). For comparison, the latter has been refined from single crystal data, too. Both the structures can be described as sequence of layers of each of two crystallographically different [Si₂O₇]^6– anions always built up of two corner‐linked [SiO4] tetrahedra in eclipsed conformation with non‐linear Si–O–Si bridges (∢(Si–O–Si) = 128–132°) piled up in [001] direction and aligned almost parallel to the c axis. They differ only in layer sequence: Whereas the double tetrahedra of the disilicate units are tilted alternating to the left and in view direction ([010]; stacking sequence: AB) in H–La₂[Si₂O₇], after layer B there follow due to the 4₁ screw axis layers with anions tilted to the right and tilted against view direction ([010]; stacking sequence: ABA′B′) in A–La₂[Si₂O₇]. The extremely irregular coordination polyhedra around each of the four crystallographically independent La³⁺ cations in both forms (H and A type) consist of eight to ten oxygen atoms in spacing intervals of 239 to 330 pm. The possibility of more or less ordered intermediate forms will be discussed.     

Neue ternäre Rhodium‐ und Iridium‐Phosphide und ‐Arsenide mit U4Re7Si6‐Struktur

New Ternary Rhodium‐ and Iridium‐Phosphides and ‐Arsenides with U₄Re₇Si₆ Type Structure Single crystals of Mg₄Rh₇P₆ (a = 7.841(1) Å), Mg₄Rh₇As₆ (a = 8.066(1) Å), Yb₄Rh₇As₆ (a = 8.254(1) Å) and Mg₄Ir₇As₆ (a = 8.082(2) Å) were prepared by heating mixtures of the elements in a lead flux and were investigated by means of X‐ray methods. The compounds are isotypic and they crystallize in the U₄Re₇Si₆ type structure (Im 3 m; Z = 2), which is formed by CeMg₂Si₂ analogous units, which are twisted against each other. The Rh(Ir) atoms building these units are coordinated tetrahedrally by the non‐metal. The P(As) atoms of six units form a regular octahedron, which is centred by an additional Rh(Ir) atom. This second structural segment corresponds to the perovskit type structure.     

Stapelvarianten aus SrPtSb‐ und CaAl2Si2‐analogen Baublöcken

Stacking Variants of SrPtSb and CaAl₂Si₂ analogous Units Structure determinations on the basis of single crystal X‐ray methods revealed, that the crystal structures of Ca₃Cu₂Zn₂P₄ (P3 m1; Z = 1; a = 4.034(1), c = 14.604(3) Å), the isotypic Eu compound (a = 4.150(9), c = 15.210(7) Å), of Ca₂CuZn₂P₃ (P6₃/mmc; Z = 2; a = 4.048(2), c = 21.466(11) Å) and Ca₄Cu₃Zn₂P₅ (P6₃/mmc; Z = 2; a = 4.041(1), c = 37.060(7) Å) respectively can be described as stacking variants built up by two different segments. The first one corresponds with the hexagonal SrPtSb structure type, the second one with the trigonal CaAl₂Si₂ structure type. The segments along [001] are arranged one another and are represented with different weightiness in the compounds concerned.     

Palladium(II) Complexes with the Mixed‐Donor Ligand CH3S‐(CH2)3‐PPh2 Crystal Structures of [PdCl2{CH3S‐(CH2)3‐PPh2}n](n = 1, 2)

The phosphorus‐sulfur ligand 1‐(methylthio)‐3‐(diphenylphosphino)‐propane (S‐P3) has been synthesized and characterized by ¹H NMR and ¹³C NMR. Reactions of S‐P3 with [PdCl₂(PhCN)₂] afforded the complexes [PdCl₂(S‐P3)] ( I ) and [PdCl₂(S‐P3)₂] ( II ), in which S‐P3 acts as a bidentate and monodentate ligand, respectively. Compound I crystallizes in monoclinic space group P2₁/n (No. 14) with cell dimensions: a = 8.589(3), b = 15.051(3), c = 17.100(3)Å, β = 102.91(2)°, V = 2154.7(9)ų, Z = 4. Likewise, compound II crystallizes in monoclinic space group P2₁/n (No. 14) with a = 9.993(5), b = 8.613(4), c = 18.721(5)Å, β = 90.18(3)°, V = 1611.3(12)ų, Z = 2. Compound II has a trans square planar configuration with only the P‐site of the ligand bonded to the palladium atom.     

[TMPA]4[Si8O20] · 34 H2O and [DDBO]4[Si8O20] · 32 H2O are heteronetwork clathrates with 1,1,4,4-tetramethylpiperazinium (TMPA) and 1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane (DDBO) guest cations

[TMPA]₄[Si₈O₂₀] · 34 H₂O ( 1 ) and [DDBO]₄[Si₈O₂₀] · 32 H₂O ( 2 ) have been prepared by crystallization from aqueous solutions of the respective quaternary alkylammonium hydroxide and SiO₂. The crystal structures have been determined by single-crystal X-ray diffraction. 1 : Monoclinic, a = 16.056(2), b = 22.086(6), c = 22.701(2) Å, β = 90.57(1)° (T = 210 K), space group C2/c, Z = 4. 2 : Monoclinic, a = 14.828(9), b = 20.201(7), c = 15.519(5) Å, β = 124.13(4)° (T = 255 K), space group P2₁/c, Z = 2. The polyhydrates are structurally related host-guest compounds with three-dimensional host frameworks composed of oligomeric [Si₈O₂₀]^8? anions and H₂O molecules which are linked via hydrogen bonds. The silicate anions possess a cube-shaped double four-ring structure and a characteristic local environment formed by 24 H₂O molecules and six cations (TMPA, [C₈H₂₀N₂]²⁺, or DDBO, [C₈H₁₈N₂]²⁺). The cations themselves reside as guest species in large, irregular, cage-like voids. Studies employing ²⁹Si NMR spectroscopy and the trimethylsilylation method have revealed that the saturated aqueous solutions of 1 and 2 contain high proportions of double four-ring silicate anions. Such anions are also abundant species in the saturated solution of the heteronetwork clathrate [DMPI]₆[Si₈O₁₈(OH)₂] · 48.5 H₂O ( 3 ) with 1,1-dimethylpiperidinium (DMPI, [C₇H₁₆N]⁺) guest cations.     

Syntheses of (C_5H_9C_5H_4)_2LnCl(THF)_n (Ln=Nd, Sm, Er, Yb) and crystal structure of [(C_5H_9C_5H_4)_2-LnCl(THF)_n]_2(Ln=Sm, n=1; Ln=Er, n=0)

Reactions of lanthanoid trichlorides with sodium cyclopentylcyclopentadienyl in THFafford bis(cyclopentylcyclopentadienyl) lanthanoid chloride complexes (C_5H_9C_5H_4)_2LnCl(THF)_n (Ln=Nd, Sm, n=1; Ln= Er, Yb, n= 0). The compound [CP'_2SmCl(THF)]_2 (2) (Cp' =cyclopentylcy-clopentadienyl) crystallizes from mixed solvent of hexane and THF in monoclinic space group P_2_1/cwith a = 11.583 (3), b = 23.019(6), c = 8.227 (2), β= 90.26 (2)°, V= 2194 (1)~3, D_c= 1.59 g/cm~3.μ= 28.6 cm~(-1), F(000) = 1060, Z= 2 (dimers). Its crystal molecule is a dimer with a crystallographicsymmetry center. The central metal atom Sm is coordinated to two Cp' rings, two bridging chlorineatoms and one THF forming a distorted trigonal bipyramid. The crystal of [Cp'_2ErCl]_2 (3) belongs tothe triclinic space group P with a = 11.264 (2), b= 13.296(5), c = 14.296(6), a = 96.99 (3), β=112.47(2), γ= 102.78(2)°, V= 1865(1)~3, D_c= 1.67 g /cm~3, μ= 48.0 cm~(-1), F(000) = 924, Z = 2 (dimers).The molecule is a dimer consisting of two Cp'_2 ErCl species bridged by two Cl atoms. The centralmetal atom Er is coordinated to two Cp' rings and two bridging chlorine atoms forming a pseudo-tetrahedron. All these complexes are soluble in THF, DME, Et_2O, toluene and hexane.     

Mesityl‐phenolato‐vanadium(III)‐Komplexe: Synthese,Struktur und Verhalten

Mesityl‐vanadium(III)‐phenolate Complexes: Synthesis, Structure, and Reactivity Protolysis reactions of [VMes₃(THF)] with ortho‐substituted phenols (2‐iso‐propyl‐(H–IPP), 2‐tert‐butyl(H–TBP), 2,4,6‐trimethylphenol (HOMes) and 2,2′biphenol (H₂–Biphen) yield the partially and fully phenolate substituted complexes [VMes(OAr)₂(THF)₂] (OAr = IPP ( 1 ), TBP ( 2 )), [VMes₂(OMes)(THF)] ( 4 ), [V(OAr)₃(THF)₂] (OAr = TBP ( 3 ), OMes ( 5 )), and [V₂(Biphen)₃(THF)₄] ( 6 ). Treatment of 6 with Li₂Biphen(Et₂O)₄ results in formation of [{Li(OEt₂)}₃V(Biphen)₃] ( 7 ) and with MesLi complexes [{Li(THF)₂}₂VMes(Biphen)₂] · THF ( 8 ) and [{Li(DME)}VMes₂(Biphen)] ( 9 ) are formed. Reacting [VCl₃(THF)₃] with LiOMes in 1 : 1 to 1 : 4 ratios yields the componds [VCl_3–n(OMes)_n(THF)₂] (n = 1 ( 5 b ), 2 ( 5 a ), 3 ( 5 )) and [{Li(DME)₂}V(OMes)₄] ( 5 c ), the latter showing thermochromism due to a complexation/decomplexation equilibrium of the solvated cation. The mixed ligand mesityl phenolate complexes [{Li(DME)_n}{VMes₂(OAr)₂}] (OAr = IPP ( 10 ), TBP ( 11 ), OMes ( 12 ) (n = 2 or 3) and [{Li(DME)₂}{VMes(OMes)₃}] ( 15 ) are obtained by reaction of 1 , 2 , 5 a and 5 with MesLi. With [{Li(DME)₂(THF)}{VMes₃(IPP)}] ( 13 ) a ligand exchange product of 10 was isolated. Addition of LiOMes to [VMes₃(THF)] forming [Li(THF)₄][VMes₃(OMes)] ( 14 ) completes the series of [Li(solv.)_x][VMes_4–n(OMes)_n] (n = 1 to 4) complexes which have been oxidised to their corresponding neutral [VMes_4–n(OMes)_n] derivatives 16 to 19 by reaction with p‐chloranile. They were investigated by epr spectroscopy. The molecular structures of 1 , 3 , 5 , 5 a , 5 a – Br , 7 , 10 and 13 have been determined by X‐ray analysis. In 1 (monoclinic, C2/c, a = 29.566(3) Å, b = 14.562(2) Å, c = 15.313(1) Å, β = 100.21(1)°, Z = 8), 3 (orthorhombic, Pbcn, a = 28.119(5) Å, b = 14.549(3) Å, c = 17.784(4) Å, β = 90.00°, Z = 8), ( 5 ) (triclinic, P1, a = 8.868(1) Å, b = 14.520(3) Å, c = 14.664(3) Å, α = 111.44(1)°, β = 96.33(1)°, γ = 102.86(1)°, Z = 2), 5 a (monoclinic, P2₁/c, a = 20.451(2) Å, b = 8.198(1) Å, c = 15.790(2) Å, β = 103.38(1)°, Z = 4) and 5 a – Br (monoclinic, P2₁/c, a = 21.264(3) Å, b = 8.242(4) Å, c = 15.950(2) Å, β = 109.14(1)°, Z = 4) the vanadium atoms are coordinated trigonal bipyramidal with the THF molecules in the axial positions. The central atom in 7 (trigonal, P3c1, a = 20.500(3) Å, b = 20.500(3) Å, c = 18.658(4) Å, Z = 6) has an octahedral environment. The three Li(OEt₂)⁺ fragments are bound bridging the biphenolate ligands. The structures of 10 (monoclinic, P2₁/c, a = 16.894(3) Å, b = 12.181(2) Å, c = 25.180(3) Å, β = 91.52(1)°, Z = 4) and 13 (orthorhombic, Pna2₁, a = 16.152(4) Å, b = 17.293(6) Å, c = 16.530(7) Å, Z = 4) are characterised by separated ions with tetrahedrally coordinated vanadate(III) anions and the lithium cations being the centres of octahedral and trigonal bipyramidal solvent environments, respectively.     

Quaternäre Magnesium-Iridiumboride Mg2Xlr5B2 mit X = Be,Al, Si,P, Ti,V, Cr,Mn, Fe,Co, Ni,Cu, Zn,Ga, Ge,As – eine Besetzungsvariante des Ti3Co5B2-Typs

Quaternary Magnesium Iridium Borides Mg₂XIr₅B₂ with X = Be, Al, Si, P, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As – a Substitution Variant of the Ti₃Co₅B₂ Type of Structure The compounds Mg₂XIr₅B₂ with X = Be, Al, Si, P, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge and As crystallize tetragonally with Z = 2 in the space group P4/mbm. The lattice constants are in the range a = 9.199 Å, c = 2.880 Å for Mg₂BeIr₅B₂ und a = 9.406 Å, c = 2.953 Å for Mg₂TiIr₅B₂ (further lattice constants are given in Table 1). X-ray structure determinations carried out with single crystals of the Si-and the P-compounds showed that a substitution variant of the Ti₃Co₅B₂ type of structure is formed. According to X-ray powder photographs the other compounds are isotypic. In the compounds with X = P and As the X-siteset is only occupied at about 70% and 80% respectively.