M. R. Spirlet

The first cationic indenyl-f-metal complexes with pentagonal bipyramidal geometry. Crystal structures of [C9H7UBr2(CH3CN)4]+2 [UBr6]2− and [{C9H7UBr(CH3CN)4}2O]2+ [UBr62−☆

Abstract Treatment of the octahedral complexes, C9H7AnHal3·2C4H8O (An = U r Th) with verypure methyl cyanide leads to the formation of the novel complexes [C9H7AnHal2(CH3CN)4]+2 [AnHal62− (I). Reaction of C9H7UHal3·2C4H8O with methyl cyanide containing dry oxygen gives the red complex [{C9H7UHal-(CH3CN)4}2O]2+ [UHal6]2− (II). Both uranium complexes with Hal = Br have been characterized by elemental analysis, vibration spectroscopy and X-ray structure analysis. The cation in I exhibits a pentagonal bipyramidal geometry and that in II consists of two pentagonal bipyrmids bonded by an oxygen occupying the common apex. A series of analogous compounds containing the 1-ethylindenyl, 1, 4, 7-trimethylindenyl or 1,2,3,4,5,6,7-heptamethylindenyl anion has been prepared and characterized . The reactions of the octahedral compounds with butyronitirle and benzonitrile is discussed.

Modification of calix[4]arenes with CMPO-functions at the wide rim. Synthesis, solution behavior, and separation of actinides from lanthanides.

Two calix[4]arene tetraethers (Y = C5H11, C14H29) bearing on their wide rim four -N(Me)-CO-CH2-P(O)Ph2 residues were synthesized for the first time. Their ability to extract lanthanides and actinides from an acidic aqueous phase to organic phases (CH2Cl2, NPHE) was studied. In comparison to the corresponding -NH-analogs, they are less efficient extractants, the selectivity for the light over the heavy lanthanides is less pronounced, while there is still an interesting selectivity of Am3+ over Eu3+. Stability constants for selected lanthanide salts were determined also in homogenous phase (methanol, acetonitrile) but do not account for the different extraction results. The complexation of Gd3+ was also followed by relaxivity (NM RD) measurements, which suggest an even stronger aggregation for the N-methyl compound while the 1:1 complex is reached for a smaller ratio [L]/[Gd3+] compared to the NH analog. The formation of aggregates is also supported by dynamic light scattering measurements. A single crystal X-ray structure of the pentyl ether reveals a C2-symmetrical pinched cone conformation for the free ligand.

Oxo-bridged bimetallic organouranium complexes: The crystal structure of μ-oxo-bis[tris(cyclopentadienyl)uranium(IV)]

Abstract Oxidation of (C 5 H 5 ) 3 U III ·THF with oxygen in tetrahydrofuran yields the linear bridged complex [(C 5 H 5 ) 3 U][μ-O]. Three cyclopentadienyl rings are η 5 -covalently bonded to each uranium atom to form a distorted tetrahedron with one bridging oxygen atom. The UOU angle is 180° with the oxygen atom on a centre of inversion. The UO distance, 2.0881(4) A, is among the shortest ever observed. The temperature-dependent paramagnetic susceptibility of the compound was measured in the temperature range between 4.2 and 300 K and is discussed in comparison with the magnetic susceptibilities of (C 5 H 5 ) 3 UOH, (C 5 H 5 ) 3 USH and [(C 5 H 5 ) 3 U] 2 [μ-S].

Ferrorosemaryite, NaFe2+Fe3+Al(PO4)3, a new phosphate mineral from the Rubindi pegmatite, Rwanda

Ferrorosemaryite, ideally □ NaFe2+Fe3+Al(PO4)3, is a new mineral species from the Rubindi pegmatite, Rwanda. It occurs as large idiomorphic grains reaching 3 mm, embedded in scorzalite. Associated phosphate minerals are scorzalite, trolleite, montebrasite, bertossaite, brazilianite, with accessory augelite, triplite and lacroixite. The mineral is transparent and exhibits a dark-green to bronze colour, with a resinous lustre and with a greenish to brownish streak. It is non-fluorescent, brittle, and shows a perfect {010} cleavage and a good {101} cleavage. The estimated Mohs hardness is 4. The calculated density is 3.62 g/cm3. Ferrorosemaryite is biaxial negative, with α = 1.730(5), β = 1.758(7), and γ= 1.775(5) (Λ = 590 nm). Pleochroism is from dark green ( X ) to dark brown ( Z ). The measured 2 V angle is 82(1)°, and the calculated 2 V angle is 75°. A strong dispersion r < v has been observed, but the optical orientation has not been determined. Electron microprobe analyses gave P2O5 46.00, Al2O3 9.12, Fe2O3 21.01, FeO 11.10, MgO 0.19, MnO 7.96, CaO 0.44, Na2O 2.85, K2O 0.01, total 98.68 wt. %. The resulting empirical formula, calculated on the basis of 12 O, is □1.00(Na0.42Mn2+0.28Ca0.04□0.26)Σ1.00(Fe2+0.71Mn2+0.24Fe3+0.05)Σ1.00Fe3+1.00(Al0.82Fe3+0.16Mg0.02)Σ1.00[(P0.99□0.01)O4]3. The single-crystal unit-cell parameters are a = 11.838(1), b = 12.347(1), c = 6.2973(6) A, β = 114.353(6)°, and V = 838.5(1) A3, space group P 21/ n . The eight strongest lines in the powder X-ray diffraction pattern [ d (in A)( I )( hkl )] are: 8.102(30)(110), 6.167(50)(020), 5.382(40)(200), 4.054(45)(220), 3.448(65)(310), 3.011(40)(112), 2.693(75)(400), 2.677(100)(240). Ferrorosemaryite is the Fe2+ analogue of rosemaryite, and belongs to the wyllieite group of minerals. The crystal structure of ferrorosemaryite has been refined, based on single-crystal X-ray diffraction data, to R 1 = 2.43 %. The infrared spectrum is similar to those of alluaudite-type phosphates. The mineral species and name were approved by the Commission on New Minerals and Mineral Names of the International Mineralogical Association (no. 2003–063).

Dicyclopentadienyl complexes of ytterbium(III). The crystal structure of [Yb(η5-C5H4SiMe3)2(μ-Cl)]2

Abstract The title complex was prepared by reaction of YbCl 3 with Li (C 5 H 4 SiMe 3 ) in tetrahydrofuran. A single crystal X-ray diffraction study has revealed that the complex is dimeric with bridging chlorine atoms. A flattened tetrahedron around each ytterbium atom is formed by the centroids of two cyclopentadienyl rings and the two bridging chlorine atoms. Comparison of bond distances and angles with those reported for similar dicyclopentadienylytterbium complexes shows that substitution on the cyclopentadienyl ligands by bulky trimethylsilyl groups does not affect the stereochemistry about the lanthanide atom.

The X-ray structure of 1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetic acid and its relevance to the protonation of polyaza polycarboxylic macrocycles

The tetraprotonated form of the macrocyclic ligand teta (1,4,8,11-tetraazacyclotetradecane-1,4,8,11-tetraacetate) crystallizes in the monoclinic system, space group P21/c, a= 7.816(2), b= 14.656(2), c= 11.647(3)A, β= 102.52(4)°, Z= 2. The structure was refined from diffractometer data to an R value of 0.035 and the hydrogen atoms were located unequivocally. In agreement with previous NMR investigations, H4teta features two protonated nitrogen atoms in the ring and two protonated carboxylate groups. The electrostatic repulsion is thus reduced to a minium. The tetraaza ring adopts a quadrangular [3434] conformation which is one of the most stable geometric arrangements of the 14-membered cycles. The ligand forms no intramolecular hydrogen bonds but it is involved in intermolecular hydrogen bonds with water molecules.

X-ray crystal structure analysis of tetrakis(indenyl) thorium

Abstract Th(C 9 H 7 ) 4 crystallizes in space group Pna 2 1 with cell dimensions a = 22.403(5), b = 36.034(7), c = 9.566(2) A . There are 12 molecules in the whole cell of which three are symmetrically independent. Three dimensional X-ray intensity data were collected with an Enraf-Nonius four-circle diffractometer. The structure was solved by direct methods, Fourier techniques and full-matrix refinement. The agreement factors are R = 0.04 and R w = 0.04 for 3468 independent reflections ( I ⩾ 1.5 σ ( I )). The crystal structure exhibits stacking disorder, a simple basic pseudostructure being modulated over the b -axis to give the triple true cell. Coordination about each thorium atom is a slightly distorted tetrahedron. The Th-C distances to the five membered rings of the indenide ligands indicate trihapto character of the metal-carbon bonding.

Structure of tris(η5-cyclopentadienyl)uranium thiocyanate

Tris(η 5 -cyclopentadienyl)(thiocyanato-N)-uranium, [U(NCS)(C 5 H 5 ) 3 ], M r =491.40, orthorhombic, Pca2 1 , α=15.427 (2), b=8.323 (3), c=11.772 (5) A, V=1511 (1) A 3 , Z=4, D x =2.159 g cm -3 , λ(Mo Kα)=0.71073 A, μ=103.0 cm -1 , F(000)=904, T=295 (1) K, R=0.043 for 902 reflections [I>3σ(I)]

X-ray crystal structure analysis of barium tetrakis(oxalato) uranium(IV) octahydrate, Ba2U(C2O4)4·8H2O☆

Abstract Ba2U(C2O4)4·8H2O crystallizes in space group C2 c with cell dimensions a = 10.388(2), b = 28.703(3), c = 9.261(1) A , β = 123.55(1) ° and z = 4. The structure was solved by direct methods and refined, on 1823 (I > 3σ(I)) unique reflections, with full matrix least-squares to R = 0.029 (Rw = 0.046). The uranium atom is nine-coordinated to four oxalate groups acting as bidentate ligands and to one water molecule. The coordination geometry about the uranium is on the pathway between the tricapped trigonal prism and the capped square antiprism. The crystal stacking is achieved by a remarkable network of Ba-O interactions and O-O hydrogen bonds.

KZn(HP2O7)·2H2O and KMn(HP2O7)·2H2O: acid pyrophosphate metallates(II) with layer structures

The crystal structures of the isomorphous title compounds, namely potassium zinc hydrogen pyrophosphate dihydrate and potassium manganese hydrogen pyrophosphate dihydrate, consist of acidic pyrophosphate-metallate(II) layers joined by K(+) ions and hydrogen-bridging bonds. The Zn(2+)/Mn(2+) ions are octahedrally surrounded by four pyrophosphate O atoms and by two water molecules. The (HP(2)O(7))(3-) anions exhibit eclipsed conformations. The metal ions and water O atoms lie on mirror planes, as does the central O atom of the (HP(2)O(7))(3-) anion.