Struktur‐ und magnetochemische Untersuchungen an Ba5Mn3F19 und verwandten Verbindungen AII5MIII3F19

Structural and Magnetochemical Studies of Ba₅Mn₃F₁₉ and Related Compounds A^II₅M^III₃F₁₉ Single crystal structure determinations by X‐ray methods were performed at the following compounds, crystallizing tetragonally body‐centred (Z = 4): Sr₅V₃F₁₉ (a = 1423.4(2), c = 728.9(1) pm), Sr₅Cr₃F₁₉ (a = 1423.5(2), c = 728.1(1) pm), Ba₅Mn₃F₁₉ (a = 1468.9(1), c = 770.3(1) pm, Ba₅Fe₃F₁₉ (a = 1483.5(1), c = 766.7(1) pm), and Ba₅Ga₃F₁₉ (a = 1466.0(2), c = 760.1(2) pm). Only Ba₅Mn₃F₁₉ was refined in space group I4cm (mean distances for elongated octahedra Mn1–F: 185/207 pm equatorial/axial; for compressed octahedra Mn2–F: 199/182 pm), the remaining compounds in space group I4/m. In all cases the octahedral ligand spheres of the M1 atoms showed disorder, the [M1F₆] octahedra being connected into chains in one part of the compounds and into dimers in the other. The magnetic properties of the V, Cr and Mn compounds named above and of Pb₅Mn₃F₁₉ and Sr₅Fe₃F₁₉ as well were studied; the results are discussed in context with the in part problematic structures.     

Struktur‐ und magnetochemische Untersuchungen an den ternären Phosphaten Ba2MII(PO4)2 (MII = Mn,Co) und Strukturverfeinerung von BaNi2(PO4)2

Structural and Magnetochemical Studies at the Ternary Phosphates Ba₂M^II(PO₄)₂ (M^II = Mn, Co) and Refinement of the Crystal Structure of BaNi₂(PO₄)₂ Single crystals of the following phosphates were grown by the floating zone technique using a mirror furnace and their crystal structures refined (0,02 < R₁ < 0,04 and 0,04 < wR₂ < 0,10, resp.): Ba₂Mn(PO₄)₂ (a = 531.1(1), b = 896.8(1), c = 1625.6(3) pm, β = 90.26(1)°), Ba₂Co(PO₄)₂ (a = 529.8(1), b = 884.4(1), c = 1614.4(3) pm, β = 90.68(2)°) and BaNi₂(PO₄)₂ (a = 480.0(1), c = 2327.3(5) pm, Z = 3, space group R3). Both compounds Ba₂M^II(PO₄)₂ crystallize with Z = 4 in space group P2₁/n of the monoclinic Ba₂Ni(PO₄)₂ type; BaNi₂(PO₄)₂ has the hexagonal‐rhombohedral structure of the BaNi₂(AsO₄)₂ type. Magnetic measurements of powders of Ba₂Mn(PO₄)₂ and Ba₂Co(PO₄)₂ yielded room temperature moments of μ_eff = 5,73 and 4,93 μ_B, resp., but only the manganese compound obeys the Curie‐Weiss law down to low temperatures. Weak antiferromagnetic interactions at both compounds only near T_M ≈ 5 K lead to a reciprocal susceptibility minimum.     

Synthese und Kristallstrukturanalyse von NaSrMg2F7, einer vollständig fluorierten Verbindung des Pyrochlortyps

Synthesis and Crystal Structure Analysis of NaSrMg₂F₇, a Fully Fluorinated Compound of the Pyrochlore Family During our research on alkali‐fluorides, the compound NaSrMg₂F₇ has been prepared by a precipitation reaction of Sr²⁺, Mg²⁺ and Na⁺ with F^– for the first time. The powder crystallizes as a single phase in the form of spherical agglomerates ∼0.25 μm in diameter. The compound crystallizes in the space group Fd 3 m (Nr. 227) with lattice parameter a = 10.4379(4) Å. Structural analysis by the Rietveld method was done from X‐ray diffraction data. In agreement with the structure analysis, spectroscopical investigations confirm the presence of two coupled fluoride ions. The crystal structure corresponds to the pyrochlore structure type A₂B₂X₇ with 50% occupation of Sr²⁺ or Na⁺ at the A site.     

Struktur und Magnetismus von Fluoriden Cs2MCu3F10 (M = Mg,Mn, Co,Ni), Varianten des CsCu2F5‐Typs

Structure and Magnetism of Fluorides Cs₂MCu₃F₁₀ (M = Mg, Mn, Co, Ni), Variants of the CsCu₂F₅ Type X‐ray structure determinations of single crystals showed that compounds Cs₂MCu₃F₁₀ crystallize with Z = 2 in space group P2₁/n (No.14) (M = Mn) of the CsCu₂F₅ type resp. in its supergroup I2/m (No.12) (M = Mg, Co, Ni). Cs₂MgCu₃F₁₀: a = 714.9(1), b = 736.8(1), c = 940.4(1) pm, b = 96.29(1)°, (Mg‐F: 199.2 pm); Cs₂MnCu₃F₁₀: a = 725.1(1), b = 742.7(1), c = 951.0(2) pm, b = 97.28(3)°, (Mn‐F: 209.1 pm); Cs₂CoCu₃F₁₀: a = 717.8(3), b = 739.1(2), c = 939.4(4) pm, b = 97.49(2)°, (Co‐F: 203.1 pm); Cs₂NiCu₃F₁₀: a = 716.3(1), b = 737.7(1), c = 938.2(2) pm, b = 97.09(1)°, (Ni‐F: 201.0 pm). As determined directly for the Mg compound and generally concluded from the average distances M‐F noted, M substitution concerns mainly the octahedrally coordinated position of the CsCu₂F₅ structure, the distortion of which is very much reduced thereby. Within the remaining [CuF₄] and [CuF₅] coordinations, in contrast to CsCu₂F₅, one F ligand is disordered, in case of the Mn compound the pyramidally coordinated Cu atom, too. The magnetic properties are complex and point to frustration and spin glass effects. Only at the diamagnetically substituted variants with M = Mg, Zn no Néel point appears, which is reached at 27, 23, 36 and 55 K for M = Mn, Co, Ni and Cu, resp. At lower temperatures ferri‐ resp. weak ferromagnetism and hysteresis is observed.     

Darstellung,Eigenschaften und Molekülstrukturen von Dimethylmetallalkoxiden und ‐amiden des Aluminiums und Galliums

Preparation, Properties, and Molecular Structures of Dimethylmetal Alkoxides and Amides of Aluminium and Gallium Dimethylaluminium‐ ( 1 ) and Dimethylgallium‐o‐methoxyphenyl‐1‐ethoxide ( 2 ) were obtained by reaction of Me₃Al and Me₃Ga respectively with o‐Methoxyphenyl‐1‐ethanol in n‐pentane. Dimethylaluminium‐ ( 3 ) and dimethylgallium‐o‐methoxyphenyl‐2‐ethylamide ( 4 ) were prepared by treatment of Me₂AlCl and Me₂GaCl respectively with Lithium‐o‐methoxyphenyl‐2‐ethylamide. Trimethylgallium‐o‐methoxyphenylmethylamine‐Adduct ( 5 ) was isolated using reaction of Me₃Ga with the corresponding amine. The compounds were characterised by ¹H‐, ¹³C‐, and ²⁷Al n.m.r. spectroscopy. The molecular structures of 2 and 5 were determined by X‐ray diffraction. Compounds 1 – 4 form brigded dimeric molecules. The bond distances of the central Ga₂O₂ ring in 2 correspond to those of compounds of similar structure.     

Crystal Structure and Magnetic Exchange in the Single Chloride‐Bridged Copper(II) Chain Compound [CuCl2(TzHy)] [TzHy = (4,5‐dihydro‐1,3‐thiazol‐2‐yl)hydrazine]

The copper complex [CuCl₂(TzHy)] has been synthesized and its crystal structure determined. The coordination complex contains polymeric [CuCl₂(TzHy)]_n chains in which the units are linked by μ‐chloro bridges. The chains run along the crystallographic c axis. The geometry around the copper(II) is best described as distorted square pyramidal. The equatorial positions are occupied by Cl(1) and Cl(2) ligands and one thiazolinic nitrogen atom and another hydrazinic nitrogen atom, from TzHy ligand. The axial position is occupied by the Cl(2b) ligand. The magnetic susceptibility measurements in the temperature range 4 – 290 K show a weak antiferromagnetic intrachain interactions (J = ?8.6 cm^?1).     

Spektroskopische und röntgenographische Untersuchungen an Dichlormethyl-Quecksilberverbindungen

Spectroscopic and X-Ray Structural Investigations on Dichloromethyl Mercury Compounds Bis(dichloromethyl)mercury, Hg(CHCl₂)₂, and mixed alkyl compounds RHgCHCl₂ (with R = CH₃, C₂H₅) have been synthesized by known methods from CH₂Cl₂, lithium butanide and HgCl₂, CH₃HgCl or C₂H₅HgCl, respectively. The ¹H-, ¹³C-NMR as well as the IR and Raman spectra of the liquid alkyls RHgCHCl₂ and the high melting Hg(CHCl₂)₂ have been measured and assigned. According to the X-ray structure determination Hg(CHCl₂)₂ crystallizes in the monoclinic space group P2₁/c with 4 non-symmetric molecules per unit cell (R = 0.046).     

Neue Fluorozirconate und ‐hafnate mit V2+ und Ti2+

New Fluorozirconates and ‐hafnates with V²⁺ and Ti²⁺ During investigations of the systems MF₂/KF/MF₄ e. g. MF₂/NaF/MF₄ (M²⁺ = Ti²⁺, V²⁺, M⁴⁺ = Zr⁴⁺, Hf⁴⁺) we obtained blue crystals of VZrF₆, VHfF₆, KVZrF₇, blue‐green crystals of NaVHf₂F₁₁, yellow crystals of TiHfF₆ and NaTiHf₂F₁₁, and yellow to rubyred crystals of TiZrF₆, respectively. According to single crystal data, VZrF₆ VHfF₆ and TiZrF₆ crystalizes in the ordered ReO₃‐type (cubic, Fm3m, a = 812,1(5), 804,2(8), and 821,0(2) pm, Z = 4). TiHfF₆ crystalizes in a high‐temperature‐modification (cubic, ReO₃‐type, Pm3m, a = 392,3(2) pm, Z = 2). KVZrF₇ is isotyic to KPdZrF₇ (orthorhombic, Pnna, a = 1109,8(6), b = 788,0(7), c = 648,0(15) pm, Z = 4). NaTiHf₂F₁₁ and NaVHf₂F₁₁ crystalizes monoclinic (C2/m, a = 910,5(7), b = 675,9(7), c = 773,6(5) pm, β = 116,10(6)° and a = 917,7(5), b = 685,7(5), c = 752,4 pm, β = 118,28(1)°, Z = 2, respectively) and are also isotypic to already known AgPdZr₂F₁₁.     

Das Hexagallan [Ga6{SiMe(SiMe3)2}6] und das closo‐Hexagallanat [Ga6{Si(CMe3)3}4(CH2C6H5)2]2— — der Übergang zu einem ungewöhnlichen precloso‐Cluster

The Hexagallane [Ga₆{SiMe(SiMe₃)₂}₆] and the closo‐Hexagallanate [Ga₆{Si(CMe₃)₃}₄ (CH₂C₆H₅)₂]^2— — the Transition to an Unusual precloso‐Cluster The closo hexagallanate [Ga₆R₄(CH₂Ph)₂]^2— (R = Si^tBu₃) as well as the hexagallane Ga₆R₆ (R = SiMe(SiMe₃)₂) with only six cluster electron pairs were isolated from reactions of “GaI” with the corresponding silanides. The structure of the latter is derived from an octahedron by a Jahn‐Teller‐distortion and is different from the capped trigonal bipyramidal one expected by the Wade‐Mingos rules. Both compounds were characterized by X‐ray crystallography. The bonding is discussed with simplified Ga₆H₆ and Ga₆H₆^2— models via DFT methods.     

Der Chemische Transport von Kupfer/Gallium‐ und Silber/Gallium‐Phasen

Chemical Vapor Transport of Intermetallic Systems. 10. Chemical Transport of Copper/Gallium and Silver/Gallium Phases The solid solution of gallium in copper and the ζ‐ and the γ‐phase can be prepared by CVT‐methods using iodine as transport agent. The solid solution of gallium in silver and the ζ‐phase and the ζ′‐phase can also prepared by CVT‐methods. Thermodynamic calculations allow to understand why these phases can be prepared by this manner.     

Struktur‐Eigenschafts‐Beziehung von Cu5Pb6O3Cl11, einer gut Kupferionen leitenden Verbindung

Structure‐Behaviour‐Relation of Cu₅Pb₆O₃Cl₁₁, a Good Solid State Ionic Conductor for Cu⁺‐Ions A new compound within the group of coin metal lead(II) oxide halides is found and characterized by X‐ray single crystal structure determination in a temperature range from 120 K to 400 K. Cu₅Pb₆O₃Cl₁₁ shows a new crystal type structure with a = 21.098(4) Å, b = 10.233(2) Å, c = 12.224(2) Å, β = 124.08(3)°, Z = 4 and space group C 2/c (No. 15) at 120 K. There are found isolated oxidic chains built of OPb₄ tetrahedra beside columnar areas consisting of CuCl. In this halidic partial structure are a lot of empty and partially occupied Cl₄‐tetrahedra. This structural characteristic seems to be source of a very good conductivity of copper ions, like in microscopic and nanoscaled composites of Al₂O₃ and AgI.     

Struktur und 1D‐magnetische Eigenschaften von (pipzH2)[MnF4(H2PO4)]

Structure and 1D‐magnetic properties of (pipzH₂)[MnF₄(H₂PO₄)] From hydrofluoric and phosphoric acid solution of Manganese(III), using piperazinium(2+) counter cations (pipzH₂²⁺) the chain‐anion [MnF₄(H₂PO₄)]^2— can be stabilized providing an interesting model system for studying the magnetic exchange interaction via phosphate bridges. Depending on the HF/H₃PO₄ excess (pipzH₂)[MnF₄(H₂PO₄)] crystallizes in two polymorphs I und II , differing mainly in the orientation of the cations. Form I is monoclinic, space group P2₁/c, Z = 4, a = 6.749(1), b = 12.039(1), c = 12.501(1) Å, β = 94.420(4)°, R = 0.023, Form II crystallizes in the same space group type P2₁/c, Z = 4, a = 6.651(1), b = 12.799(1), c = 12.825(1) Å, β = 110.312(5)°, R = 0.037. The Mn³⁺ ions are octahedrally surrounded by four terminal fluoride ligands and axially by bidentate bridging dihydrogenphosphate groups. The shape of the chain anions is very close in both modifications and characteristic for ferrodistortive Jahn‐Teller ordering.The Mn—O‐bonds along the chain direction are strongly elongated (distances 2.16 to 2.21 Å) whereas all Mn—F bond (1.81—1.88Å) are ruther short. On a large single crystal of form I 1D‐antiferromagnetic properties were found. By fitting an appropriate model based on the temperature dependence of the correlation lengths using an anisotropy constant D/k = —2.9 K a remarkably high exchange energy of J/k = —1.6(1) K along the chains could be determined.     

Bildung des „superoktaedrischen”︁ Heteropolyanions [Ni(TaF6)6]4− bei der Oxidation von Tantal mit Ammoniumfluorid an der Monel-Wand

Formation of the “Superoctahedral” Heteropolyanion [Ni(TaF₆)₆]^4? through Oxidation of Tantalum with Ammonium Fluoride at the Monel-Container Wall A few single crystals of (NH₄)₄[Ni(TaF₆)₆] are obtained besides (NH₄)[TaF₆] as the main product of the reaction of (NH₄)F with tantalum powder in an He-are-welded Monel metal container at 400°C. The crystal structure (trigonal, R-3c (Nr. 167), Z = 6, a = 1723,0(2); c = 2166,6(2) pm; R1 = 0,0303, _WR2 = 0,0609) contains the superoctahedral heteropolyanion [Ni(TaF₆)₆]^4? and (NH₄)⁺ ions; it may be recognized as a derivative structure of the K₄CdCl₆ type according to (NH₄)₄[Ni(TaF₆)₆]?K₄[Cd(Cl)₆].     

Zur Abgrenzung der PbFCl‐ und Cu2Sb‐Strukturfamilien: Neubestimmung und Verfeinerung der Kristallstrukturen von CuMgSb,Cu2Sb und CuMgAs

Demarcation of the PbFCl and Cu₂Sb Structure Families: Crystal Structure Re‐Determinations and Refinements of CuMgSb, Cu₂Sb, and CuMgAs The crystal structures of CuMgSb, Cu₂Sb, and CuMgAs have been re‐determined and refined from single crystal data, and the structural relationship between CuMgSb (cubic), Cu₂Sb (tetragonal) and CuMgAs (orthorhombic) is discussed in detail. CuMgAs does not crystallize in the Cu₂Sb type, as assumed until now; but in a new structure type oP24 (Pnma; Z = 8): a = 1346.0(1) pm, b = 395.40(3) pm, c = 739.58(6) pm. The structure is related to Cu₂Sb and can be derived from it following the principle of ′chemical twinning′. The re‐determined parameters of Cu₂Sb are included in a structure field diagram together with additional representatives of the PbFCl type. The structure field can be devided into three regions with the prototypes PbFCl, Cu₂Sb, and Fe₂As, respectively. The assignment can be related to the predominant type of bonding of each structure.     

(n‐Bu4N)2[Au(mnt)2]: Synthese,Struktur‐ und EPR‐Untersuchungen eines stabilen,mononuklearen AuII‐Komplexes

The reaction of [Au^III(mnt)₂]^? with (n‐Bu₄N)[BH₄] in acetone leads to the formation of [Au^II(mnt)₂]^2?, which is the second stable mononuclear Au^II complex characterized by X‐ray structure analysis. (n‐Bu₄N)₂[Au^II(mnt)₂] crystallizes triclinic, P (a = 904.24(5), b = 989.55(5), c = 1627.35(10) pm, α = 92.040(7), β = 94.937(7), γ = 107.220(6)°, Z = 1) with two molecules acetone per unit cell. The anion is planar. From EPR investigations using single crystals of (n‐Bu₄N)₂[Au^II(mnt)₂] the g tensor components were derived. Information about magnetic exchange interactions were obtained from line width analyses.     

Synthese,Strukturen, EPR‐ und ENDOR‐spektroskopische Untersuchungen an Übergangsmetallkomplexen von N,N‐Diisobutyl‐N′‐(2, 6‐difluor)benzoylselenoharnstoff

Synthesis, Structures, EPR and ENDOR Investigations on Transition Metal Complexes of N, N‐diisobutyl‐N′‐(2, 6‐difluoro)benzoyl selenourea The synthesis and the structures of the Ni^II and Pd^II complexes of the ligand N, N‐diisobutyl‐N′‐(2, 6‐difluoro)benzoylselenourea HBuⁱ₂dfbsu are reported. The ligands coordinate bidentately forming bis‐chelates. The structure of the ligand could not be obtained, however, the structure of its O‐ethyl ester will be reported. Attempts to prepare the Cu^II complex result only in the formation of oily products. However, the Cu^II complex could be incorporated into the corresponding Ni^II and Pd^II compounds. From this diamagnetically diluted powder and single‐crystal samples were obtained being suitable for EPR‐ENDOR measurements. We report X‐ and Q‐band EPR investigations on the systems [Cu/Ni(Buⁱ₂dfbsu)₂] and [Cu/Pd(Buⁱ₂dfbsu)₂] as well as a single‐crystal X‐band EPR study for [Cu/Ni(Buⁱ₂dfbsu)₂]. The obtained ^{63, 65}Cu and ⁷⁷Se hyperfine structure tensors allow a determination of the spin‐density distribution within the first coordination sphere. In addition, orientation selective ¹⁹F Q‐band pulse ENDOR investigations on powder‐samples of [Cu/Ni(Buⁱ₂dfbsu)₂] have been performed. The hyperfine structure tensors of two intramolecular ¹⁹F atoms could be determined. According to the small ¹⁹F couplings only a vanishingly small spin‐density of < 1 % was obtained for these ¹⁹F atoms.