Christian Schwickert

Open-shell first-row transition-metal polyhydride complexes based on the fac-[RuH3(PR3)3]- building block.

High‐spin hydrides : A new class of stable paramagnetic polyhydride complexes [M{Ru(μ‐H)3(PTol3)3}2] (M=Cr–Ni) with an unprecedented trinuclear arrangement has been synthesized. The high‐spin central 3d metal ion is sandwiched between six hydride ligands in a distorted octahedral fashion.

Anosovite-type V3O5: a new binary oxide of vanadium.

The reaction of either V(2)F(6)·4H(2)O or a mixture of 60 wt % VF(2)·4H(2)O and 40 wt % VF(3)·3H(2)O with a water-saturated gaseous mixture of 15-20 vol % hydrogen in argon leads to the formation of a new polymorph of V(3)O(5) crystallizing in the orthorhombic anosovite-type structure. Quantum-chemical calculations show that the anosovite-type structure is about 15 kJ/mol less stable than the corresponding monoclinic Magnéli phase. In addition, there are no imaginary modes in the phonon density of states, supporting the classification of the anosovite-type phase as a metastable V(3)O(5) polymorph. Susceptibility measurements down to 3 K reveal no hint for magnetic ordering.

Structure Refinement and Magnetic Properties of Ce2RuAl3 and a Group-Subgroup Scheme for Ce5Ru3Al2

The hexagonal Laves phase Ce2RuAl3 (≡ CeRu0.5Al1.5) was synthesized by high-frequencemelting of the elements in a sealed tantalum tube and subsequent annealing. The structure was refined from single-crystal X-ray diffraction data: MgZn2 type, P63/mmc, Z = 2, a = 565.38(9), c = 888.3(1) pm, wR2 = 0.0231, 193 F2 values and 13 parameters. The 2a (0.824 Ru + 0.176 Al) and 6h (0.956 Al + 0.044 Ru) Wyckoff positions show mixed occupancies leading to the composition CeRu0.48Al1.52 for the investigated crystal. The aluminum atoms build up Kagomé networks at z = 1/4 and z = 3/4 which are connected to a three-dimensional network by the ruthenium atoms. The cerium atoms fill cavities of coordination number 16 (3 Ru + 9 Al + 4 Ce) within the [RuAl3] network. The Ce2RuAl3 sample orders ferromagnetically at TC = 8.0(1) K. The cerium-rich aluminide Ce5Ru3Al2 shows unusually short Ce-Ru distances of 253 and 260 pm for the Ce1 position as a result of intermediate cerium valence. The structural distortions are discussed on the basis of a group-subgroup scheme for Pr5Ru3Al2 (space group I213) and the superstructure variant Ce5Ru3Al2 (space group R3). Graphical Abstract Structure Refinement and Magnetic Properties of Ce2RuAl3 and a Group-Subgroup Scheme for Ce5Ru3Al2 Keywords Cerium, Intermetallics, Crystal Structure, Magnetic Properties

1,2,4,5-Benzenetetrasulfonic acid and 1,4-benzenedisulfonic acid as sulfo analogues of pyromellitic and terephthalic acids for building coordination polymers of manganese

The new polysulfonic acids H4B4S (1,2,4,5-benzenetetrasulfonic acid) and H2BDS (1,4-benzenedisulfonic acid) were used for the preparation of five manganese coordination polymers. The reactions of H4B4S and MnCO3 were performed in dimethylformamide (DMF) or N-methylpyrrolidone (NMP) as solvent in sealed glass ampoules at elevated temperatures. Two benzenetetrasulfonates could be obtained, [NH2(CH3)2]2{Mn(B4S)(DMF)2} (I) (P21/c, Z = 2, a = 942.02(5) pm, b = 1684.86(6) pm, c = 918.45(5) pm, β = 97.746(6)°, R1; wR2 (Io > 2σ(Io)) = 0.0357; 0.0771) and [HNMP]2{Mn(B4S)(NMP)2} (II) (P21/c, Z = 2, a = 931.7(1) pm, b = 1049.2(1) pm, c = 1944.9(1) pm, β = 113.529(3)°, R1; wR2 (Io > 2σ(Io)) = 0.0470; 0.0952). Both compounds exhibit anionic chains according to ∞1{Mn(B4S)2/2(L)2}2− (L = DMF, NMP). The Mn2+ ions are in octahedral coordination of oxygen atoms. The charge of the anionic chains is either compensated by dimethylammonium cations, [NH2(CH3)2+], or by protonated NMP molecules, HNMP+. Solvothermal reactions of H2BDS and MnCO3 in the solvents DMF, NMP and dimethylacetamide (DMA), respectively, yielded the disulfonates Mn(BDS)(DMF)2 (III) (P, Z = 1, a = 514.3(1) pm, b = 926.2(1) pm, c = 940.2(1) pm, α = 93.552(8)°, β = 99.993(7)°, γ = 99.237(7)°, R1; wR2 (Io > 2σ(Io)) = 0.0290; 0.0637), Mn(BDS)(DMA)2 (IV) (P, Z = 2, a = 936.00(4) pm, b = 984.94(4) pm, c = 1034.75(5) pm, α = 81.606(2)°, β = 88.941(2)°, γ = 82.364(2)°, R1; wR2 (Io > 2σ(Io)) = 0.0387; 0.1046) and Mn(BDS)(NMP)2 (V) (P, Z = 2, a = 962.97(3) pm, b = 976.76(3) pm, c = 1034.23(3) pm, α = 89.371(1)°, β = 78.839(1)°, γ = 87.604(2)°, R1; wR2 (Io > 2σ(Io)) = 0.0243; 0.0713). In the crystal structures of the three compounds, the octahedrally coordinated Mn2+ ions are linked by the disulfonate ions to layers according to ∞2{Mn(BDS)4/4(L)2} (L = DMF, DMA, NMP). The thermal analysis of all compounds shows that they can be desolvated completely and that the remaining solvent-free sulfonates exhibit decomposition temperatures up to 500 °C that is exceptionally high when compared to the respective carboxylates. Temperature-dependent magnetic susceptibility measurements of [NH2(CH3)2]2{Mn(B4S)(DMF)2} show paramagnetic behavior of the Mn2+ ions.

Magnesium-rich Intermetallics RE3RuMg7 (RE=Y, Nd, Dy, Ho) – Rows of Condensed Ru@RE6/2 Octahedra in Magnesium Matrices

The magnesium-rich intermetallic phases RE3RuMg7 (RE=Y, Nd, Dy, Ho) have been synthesized from the elements in sealed niobium ampoules and subsequently characterized by powder X-ray diffraction. The structure of the dysprosium compound was refined on the basis of single-crystal X-ray diffractometer data: Ti6Sn5 type, P63=mmc, a=1019.1(2), c=606.76(9) pm, wR2=0.0159, 439 F2 values, 19 variables. The Mg3 site shows a small degree of Mg3=Dy mixing, leading to the composition Dy3:03RuMg6:97 for the investigated crystal. The striking structural motifs in the Dy3RuMg7 structure are rows of face-sharing Ru@Dy6 octahedra and corner-sharing Mg2@Mg8Dy4 icosahedra. The rows of octahedra form a hexagonal rod-packing, and each rod is enrolled by six rows of the condensed icosahedra. Temperature-dependent magnetic susceptibility measurements of Dy3RuMg7 show Curie-Weiss behavior with an experimental magnetic moment of 10.66(1) µB per Dy atom. Antiferromagnetic ordering is detected at TN =27.5(5) K. The 5 K isotherm shows a metamagnetic transition at a critical field of HC =40 kOe Graphical Abstract Magnesium-rich Intermetallics RE3RuMg7 (RE=Y, Nd, Dy, Ho) – Rows of Condensed Ru@RE6/2 Octahedra in Magnesium Matrices

Ordered vacancies in the commensurately modulated structure of SrPt1.833☐0.167Sn2

Abstract The stannide SrPt1.833☐0.167Sn2 was synthesized from the elements in a sealed niobium tube in a high-frequency furnace. Its structure was determined by and refined on the basis of single crystal X-ray diffraction data at 300 and 90 K. The refinement of 1177/1169 F2 values with 34/37 variables leads to residuals [I≥3σ(I)] RM=0.026 (375) and RS=0.075 (53)/RM=0.0211 (408) and RS=0.0503 (128) for the 300/90 K data sets, respectively. SrPt1.833☐0.167Sn2 crystallizes with an orthorhombic (3+1)D structure with the supercentered superspace group Ccmme(0β0)s00 [β=1/3 b*, a=655.25(15), b=656.7(4), c=2062.3(5) pm]. It is related to the tetragonal CaBe2Ge2 type structure. The crystal chemistry is described and the structure solution is discussed based on (3+2)D–(3+1)D–3D group-subgroup relations in the Bärnighausen formalism. 119Sn Mössbauer spectra at ambient temperature and 78 K revealed a single signal with isomer shifts of δ=1.78(1) and δ=1.83(1) mm s–1 with quadropole splitting of ΔEQ=0.71(1) and 0.86(1) mm s–1, respectively reflecting the low-symmetric site symmetry of the tin atoms. SrPt1.833☐0.167Sn2 was classified as a Pauli-paramagnet by magnetic susceptibility measurements. Its specific heat capacity is Cpm=121.4(1) J mol–1K–1 at 300 K.

SrCo2Sn8 and BaCo2Sn8: Tin-rich Stannides with Distorted SnSn6 Octahedra within Three-dimensional [Co2Sn8] Networks

The tin-rich stannides SrCo2Sn8 and BaCo2Sn8 were synthesized from the elements in sealed tantalum tubes. They crystallize with a new structure type, space group Cccm with a=1006.0(3), b=1514.4(6), c=1385.0(6) pm for SrCo2Sn8 and a=1032.8(2), b=1516.8(3), c=1405.1(3) pm for BaCo2Sn8. The structure of the barium compound was refined on the basis of single-crystal Xray diffractometer data: wR2=0.0450, 1715 F2 values, 57 variables. The cobalt atoms have seven nearest tin neighbors with Co-Sn distances ranging from 257 to 273 pm. These CoSn7 units are condensed via common rectangular faces to [Co2Sn10] double units which build up a covalently bonded three-dimensional network through Sn-Co-Sn bridges. Larger voids left by this network are filled by the barium and the Sn2 atoms. The latter have distorted octahedral tin coordination with Sn2- Sn distances of 311 - 315 pm. The barium atoms have 13 nearest tin neighbors (352 - 399 pm Ba-Sn). Temperature-dependent magnetic susceptibility data of BaCo2Sn8 show Pauli paramagnetism. Graphical Abstract SrCo2Sn8 and BaCo2Sn8: Tin-rich Stannides with Distorted SnSn6 Octahedra within Three-dimensional [Co2Sn8] Networks

Ternary Antimonides RE4T7Sb6 (RE=Gd–Lu; T =Ru, Rh) with Cubic U4Re7Si6-type Structure

The ternary antimonides RE4T7Sb6 (RE=Gd-Lu; T =Ru, Rh) have been synthesized from the elements by arc-melting and subsequent annealing in an induction furnace. The samples have been characterized by powder X-ray diffraction. Four structures were refined on the basis of single-crystal X-ray diffractometer data: U4Re7Si6 type, space group Im3m with a=862.9(2) pm, wR2=0.0296, 163 F2 values for Er4Ru7Sb6; a=864.1(1) pm, wR2=0.1423, 153 F2 values for Yb4Ru7Sb6; a=872.0(2) pm, wR2=0.0427, 172 F2 values for Tb4Rh7Sb6; and a=868.0(2) pm, wR2=0.0529, 154 F2 values for Er4Rh7Sb6, with 10 variables per refinement. The structures have T1@Sb6 octahedra and slightly distorted RE@T26Sb6 cuboctahedra as building units. The distorted cuboctahedra are condensed via all trapezoidal faces, and this network leaves octahedral voids for the T1 atoms. The ruthenium-based series of compounds was studied by temperature-dependent magnetic susceptibility measurements. Lu4Ru7Sb6 is Pauli-paramagnetic. The antimonides RE4Ru7Sb6 with RE=Dy, Ho, Er, and Tm show Curie-Weiss paramagnetism. Antiferromagnetic ordering occurs at 10.0(5), 5.1(5) and 4.0(5) K for Dy4Ru7Sb6, Ho4Ru7Sb6 and Er4Ru7Sb6, respectively, while Tm4Ru7Sb6 remains paramagnetic. Yb4Ru7Sb6 is an intermediate-valent compound with a reduced magnetic moment of 3.71(1) μB per Yb as compared to 4.54 μB for a free Yb3+ ion Graphical Abstract Ternary Antimonides RE4T7Sb6 (RE=Gd–Lu; T =Ru, Rh) with Cubic U4Re7Si6-type Structure

Molybdenum Oxide Nitrides of the Mo2(O,N,□)5 Type: On the Way to Mo2O5

Blue-colored molybdenum oxide nitrides of the Mo2(O,N,□)5 type were synthesized by direct nitridation of commercially available molybdenum trioxide with a mixture of gaseous ammonia and oxygen. Chemical composition, crystal structure, and stability of the obtained and hitherto unknown compounds are studied extensively. The average oxidation state of +5 for molybdenum is proven by Mo K near-edge X-ray absorption spectroscopy; the magnetic behavior is in agreement with compounds exhibiting MoVO6 units. The new materials are stable up to ∼773 K in an inert gas atmosphere. At higher temperatures, decomposition is observed. X-ray and neutron powder diffraction, electron diffraction, and high-resolution transmission electron microscopy reveal the structure to be related to VNb9O24.9-type phases, however, with severe disorder hampering full structure determination. Still, the results demonstrate the possibility of a future synthesis of the potential binary oxide Mo2O5. On the basis of these findings, a tentative suggestion on the crystal structure of the potential compound Mo2O5, backed by electronic-structure and phonon calculations from first principles, is given.

New Intermetallic Zinc Compounds with Ordering Variants of the KHg2 and LT-SrZn5 Type

The intermetallic zinc compounds CaAuZn, SrPdZn, SrPtZn, SrAuZn, BaPd1.57 Zn3.43, and BaAu1.41Zn3.59 were synthesized from the elements in sealed niobium ampoules in an induction furnace. The equiatomic compounds crystallize with the orthorhombic TiNiSi-type structure, space group Pnma. Single-crystal X-ray data exhibited small degrees of Au=Zn mixing within the three-dimensional [AuZn] networks and resulted in the compositions CaAu1.02Zn0.98 and SrAu1.03Zn0.97 for two investigated single crystals. BaPd1.57 Zn3.43 and BaAu1.41 Zn3.59 adopt partially ordered versions of the LT-SrZn5 type, space group Pnma. Both structures were refined on the basis of X-ray single-crystal diffractometer data. a=1331.13(6), b=531.45(3), c=682.20(4) pm, wR=0.0245, 1138 F2 values, 39 variables for BaPd1.57Zn3.43 and a=1344.35(2), b=537.47(2), c=691.22(4) pm, wR=0.0441, 931 F2 values, 37 refined variables for BaAu1.41Zn3.59. The transition metal and zinc atoms form a complex three-dimensional network of (T, Zn)4 tetrahedra which are condensed via common corners and T/Zn-T/Zn bonds. Large cavities within these networks are filled by the barium atoms which have coordination number 19, i. e. Ba@(T, Zn)17Ba2. Graphical Abstract New Intermetallic Zinc Compounds with Ordering Variants of the KHg2 and LT-SrZn5 Type