Helmut W. Schmalle

A polymeric two-dimensional mixed-metal network. Crystal structure and magnetic properties of {[P(Ph)4][MnCr(ox)3]}

Abstract The mixed-metal ferromagnet {[P(Ph) 4 ][MnCr(ox) 3 ]} n , where Ph is phenyl and ox is oxalate, has been prepared and a two-dimensional network structure, extended by Mn(II)-ox-Cr(III) bridges, has been determined from single crystal X-ray data. Crystal data: space group R 3 c , a = b =18.783(3), c =57.283(24) A, α=β=90, γ=120°, Z =24 (C 30 H 20 O 12 PCrMn). The magnetic susceptibility data obey the Curie-Weiss law in the temperature range 260–20 K with a positive Weiss constant of 10.5 K. The temperature dependence of the molar magnetization exhibits a magnetic phase transition at T c =5.9 K. The structure is discussed in relation to the strategy for preparing molecular based ferromagnets and, in addition, it is a solution to the question of the dimensionality of the [MM′(ox) 3 ] n network, which in principle can extend two- or three-dimensionally to the crystal lattice. The optical absorption spectra of the single crystals are assigned to the ‘CrO 6 ’ chromophores. Their polarization patterns reflect the electric dipole selection rules for D 3 symmetry. A strong site selective luminescence from the chromium(III) 2 E states is observed at low temperature and the system may be suitable for studying energy transfer mechanisms.

Electronic Communication in C4‐Bridged Binuclear Complexes with Paramagnetic Bisphosphane Manganese End Groups

Building blocks for conducting polymers or NLO materials are the linear, unsaturated carbon chain bridged manganese complexes 1(n+) (n=0-2). All oxidation states were investigated spectroscopically and by X-ray structure determinations. The analytical data confirm a communication of the electrons over the C(4) chain-a prerequisite for electrical conductivity and NLO properties of oligo- or polymeric materials.

STRUCTURE AND THERMOCHEMICAL REACTIVITY OF CARUO3 AND SRRUO3

Abstract Single crystals of CaRuO3 (1) and SrRuO3 (2) have been synthesized by flux method and their structures have been determined by means of single crystal X-ray diffraction techniques. The crystallographic data are (1): formula weight fw = 189.15, orthorhombic, space group Pnma (No. 62), a = 5.524(1), b = 7.649(2), c = 5.354(1) A , V = 226.2 A 3 , Z = 4, Dx = 5.554 g cm−3, μ = 81.97 cm−1, final R = 0.031 for 297 observed reflections. (2): formula weight fw = 236.69, cubic, space group Pm 3 (No. 200), a = b = c =3.910(1) A , V = 59.8 A 3 , Z = 1, Dx = 6.572 g cm−3, μ = 275.28 cm−1, final R = 0.032 for 33 observed reflections. The thermochemical reactivity of the two phases has been investigated as function of temperature and ambient atmosphere. In oxidizing or inert gas atmospheres both compounds prove to be stable up to 1200 K. In reducing atmospheres such as molecular hydrogen, however, elementary ruthenium and the corresponding earth alkali metal oxides are obtained as microcrystalline mixtures at relatively low temperatures. The mechanisms of the reductions prove to be different.

The twin structure of La2Ti2O7: X-ray and transmission electron microscopy studies

La 2 Ti 2 O 7 , M r =485.613, monoclinic, P2 1 , a=7.812 (2), b=5.5440 (7), c=13.010 (2) A, β=98.66 (1) o , V=557.0 (4) A 3 , Z=4, T=298 K, D x =5.790 Mg m -3 , λ(Mo Kα)=0.71073 A, μ=17.86 mm -1 , F(000)=856. The crystals are twinned. The twin I and twin II intensities are superimposed in reciprocal-lattice layers with h even. The a * and b * axes of the twin components run antiparallel. The angle between a * twinI and a * twinII is 17. 12 o

Direct synthesis and single crystal structure determination of cubic pyrochlore-type tungsten trioxide hemihydrate, WO3 · 0.5H2O

Cubic pyrochlore-type WO3 · 0.5H2O has been synthesized hydrothermally directly from solution and its crystal structure determined by X-ray diffraction of a single crystal: space group Fd3m, a = 10.305(3) A, Z = 16. The structure contains corner-sharing WO6-octahedra, leaving tunnels along the [110]-directions, in which the water molecules are located. Dehydration yields cubic pyrochlore-type WO3, which transforms into the monoclinic modification at higher temperature.

Preparation, crystal structure, thermal and catalytical behaviour of copper diammine divanadate

Abstract A new copper diammine divanadate Cu(NH 3 ) 2 (VO 3 ) 2 has been synthesized and structurally characterized. The unit cell is monoclinic, space group Pc, a = 5.616(2) A , b = 5.591(1) A , c = 11.331(2) A , β = 90.91(2)°, V = 355.7(3) A 3 , Z = 2. The thermal decomposition has been studied by thermogravimetry and simultaneous mass spectrometry (TG/MS) in different atmospheres, i.e. H 2 , N 2 , He and O 2 . As solid products elemental copper on V 2 O 3 , Cu 0.95 V 2 O 5 and CuV 2 O 6 have been obtained, and depending on the actual atmosphere different volatile products such as NH 3 , H 2 O and N 2 . Independent of the pretreatment, reoxidation of the product phases leads to the ternary oxide CuV 2 O 6 . The microstructures have been characterized by scanning electron microscopy (SEM) and high resolution electron microscopy (HREM). The product decomposed in hydrogen has been tested with respect to its catalytic activity for the reduction of NO with CO.

On the crystal structures of La2Ti2O7 and La5Ti5O17: High-resolution electron microscopy

Abstract The structure of La5Ti5O17 has been examined by high-resolution transmission electron microscopy combined with powder X-ray and thermogravimetric analysis. It comprises five [TiO6] octahedra-thick layers isomorphous with {1 0 0} slabs of the LaTiO3 orthorhombic perovskite structure, bounded by crystallographic shear parallel with the perovskite [0 0 1] direction. La atoms occupy the distorted perovskitic A sites. The structure is derived from the homologous La2Ti2O7 by elimination of 1 35 of the oxygens from this four-octahedra-thick layered structure. Both compounds are members of an homologous series based on variation in the anion to cation ratio.

A new synthetic pathway for tris-μ-disulfido-μ3-thio-triangulo-trimolybdenum(IV) complexes: preparation, characterization and structure of [Mo3S(S2)3(OOCCHSCH2COOH)3]2−

Abstract A new synthetic pathway for complexes containing the polynuclear core [Mo3S7]4+ is described: [Mo3S7(S2)3]2− reacts with HBr to [Mo3S7Br6]2− which seems to be a useful intermediate for further ligand substitution. A new complex with mercapto- succinic acid C4H6O4S (H3msa) as ligand could be prepared. 1H NMR and 13C NMR spectra and X-ray crystal structure analysis are in agreement with the bidentate coordination of mercapto-succinic acid, where S− and COO− are bound to the same molybdenum atom forming a five-membered ring. A monoclinic crystal, space group C2, of the composition [C18H30N3]2[Mo3S7(Hmsa)3][Mo3S7(Hmsa)2(msa)] Br·6H2O was used for X-ray diffraction. The cell parameters are a=21.968(7), b=13.423(13), c= 18.828(3) A, β=94.23°, Z=2, Dc=1.606 g/cm3, μ(Mo Kα)=13.51 cm−1. [Mo3S7(Hmsa)3]2− is stable in water and air, and it can be precipitated from aqueous solution by the addition of large three-fold charged cations. It can be deprotonated reversibly to [Mo3S7(msa)3]5− in water. The pK values are 3.95, 4.41, 5.02 (1 M KCl, 25 °C). To confirm the above described procedure as a useful approach for [Mo3S7]4+ complexes, a similar compound with 2-mercapto-benzoic acid was also prepared.

Isomer abundance of bis(β-diketonato) complexes of titanium(IV). Crystal structures of the antitumor compound budotitane [TiIV(bzac)2(OEt)2] and of its dichloro-derivative [TiIV(bzac)2Cl2] (bzac=1-phenylbutane-1,3-dionate)

The molecular tumor inhibiting titanium compound budotitane [Ti(IV)(bzac)(2)(OEt)(2)] (1) and its dichloro-derivative [Ti(IV)(bzac)(2)Cl(2)] (2) (bzac=1-phenylbutane-1,3-dionate) have been crystallized and characterized by X-ray crystallography and further physical methods. Budotitane (1) crystallizes in the tetragonal, non-centrosymmetric space group P4(1) with two molecules in the asymmetric unit. Both molecules adopt the cis-cis-trans configuration with the acetyl ends of the benzoylacetonate ligands in the trans position. The dichloro-derivative of budotitane, [Ti(IV)(bzac)(2)Cl(2)] (2) crystallizes in the monoclinic, centrosymmetric space group P2(1)/n with one molecule only in the asymmetric unit. In contrast to budotitane (1), (2) shows a cis-trans-cis arrangement with the benzoyl groups in the trans position. In both complexes there are equal numbers of Delta and Lambda enantiomers within the unit cell. The phenyl groups in (1) as well as in (2) are in approximately coplanar conjugation to the metal enolate rings. The thermal degradation of budotitane (1) was investigated in the temperature range from 25 degrees C up to 800 degrees C and reveals the formation of Ti(IV)O(bzac(2-)) as an intermediate and of the rutile phase of TiO(2) as a final product. It may be worthwhile to introduce budotitane in the form of isomerically pure crystals in the preparation of the drug used for future tests.

Remarkable low symmetry hydrogen bonding network in the structure of ReCl2(NCMe)(NO)(PMe3)2

Abstract The title compound 1 crystallizes in the space group P21/a with Z=44, being the largest Z value for a transition metal complex observed up to now. Responsible for the unusual high number of independent molecules in the asymmetric unit is a dense network of hydrogen bonds, which do not follow the general rule of lowest entropy in crystals. Methyl groups serve exclusively as H donor groups, leading to hydrogen bonds of the type CH⋯O and CH⋯Cl. The putative appearance of bond-stretch isomers within one single crystal could be traced to a hidden disorder phenomenon. Density functional calculations provided further evidence for this conclusion.