Tris(ethanol-κO)tris­(picrato-κ2 O 1,O 2)lanthanum(III) tri-2-pyridylamine solvate

The title compound, [La(C6H2N3O7)3(C2H6O)3]·C15H12N4, has two mol­ecular building blocks, namely the neutral mononuclear adduct of lanthanum picrate with ethanol [i.e. La(pic)3:EtOH (1:3); La(pic)3 = lanthanum picrate and EtOH = ethanol] and the oligodentate aromatic nitro­gen base tri-2-pyridylamine (tpa). The asymmetric unit contains two formula units. The compound was prepared during an investigation of the stereochemistry of lanthanoid picrate complexes with O-donor ligands. The metal–ligand adduct adopts a nine-coordinate tricapped trigonal-prismatic metal atom environment. The stereochemical arrangement of the ligands about the metal core is typical of a fac-isomer with stoichiometry M(bidentate)3(monodentate)3. Face-to-face hydrogen bonds are found between the tpa mol­ecule and the ethanol ligands. One ethanol ligand is disordered over two positions, with site occupancy factors of ca 0.7 and 0.3. The oxygen atoms of a nitro group are also disordered over two positions; the site occupancy factors are ca 0.6 and 0.4

Alfred Werner revisited: Some subtleties of complex ion synthesis and isomerism

The synthesis of perhaps the best-known Wernerian complex, [Co(en)3]3+, is very efficient, but nonetheless results in the formation of various side-products. Today, the use of X-ray crystallography to characterise such materials provides new insights into the reaction pathways of the synthesis and the exact forms possible for the products. The structures of cis-[Co(en)2(H2NCH2CH2NH3)Cl]Cl[ZnCl4], cis-[Co(en)2(NH3)Cl]S2O6, [Co(en)(NH2CH2CH2N=CHCH2NH2))Cl][ZnCl4], [Co(en)2(N-CH3en)][Co(CN)6]?2 H2O and [Co(en)2(N-CH3en)][Co(CN)6], are presently discussed in this regard

Paramagnetism of caesium titanium alum

Caesium titanium alum, CsTi(SO4)(2) . 12H(2)O, is a beta alum and exhibits a large trigonal field and a dynamic Jahn-Teller effect. Exact calculations of the linear (2)T(2)xe Jahn-Teller coupling show that in the strict S-6 Site symmetry the ground multiplet consists of a Kramers doublet 2 Gamma(6) with magnetic splitting factors g(parallel to)=1.1 and g perpendicular to=0, a Gamma(4) Gamma(5) doublet at similar to 60 cm(-1) with g(parallel to)=2.51 and g(perpendicular to)=0.06 and another Gamma(4) Gamma(5) doublet at similar to 270 cm(-1) with g(parallel to)=1.67 and g(perpendicular to)=1.83. The controversial g values observed below 4.2 K, g(parallel to)=1.25 and g(perpendicular to)=1.14, are shown to arise from low symmetry distortions. These distortions couple the vibronic levels and induce into the ground state the off-diagonal axial Zeeman interaction that exists between the first excited and the ground vibronic levels. (C) 1997 American Institute of Physics

Surveying Battery Cell Sections to Determine the Composition and Spatial Distribution of Discharge Products using an Automated Microprobe

Determining the spatial distribution and composition of hydrohetaerolite in polished sections of discharged Leclanché cells requires the measurement of oxygen concentrations on microcrystalline material. This can be done if the composition of the mounting medium is included in the matrix correction of raw intensities. The method of Pouchou and Pichoir (PAP) is used initially to correct raw intensities obtained from surveys of microcrystalline standard material. Mean analyses agree well with the known compositions provided a correction is made for the oxygen content of the mounting medium. The same correction is then applied to the raw data collected when surveying cell sections, yielding spatially correlated analyses of hydro-hetaerolite formed as a discharge product. The surveying technique could be applied to lead-acid, Leclanché and alkaline cells

The Mesozoic along-strike tectono-metamorphic segmentation of Longmen Shan (eastern Tibetan plateau)

The Longmen Shan belt (eastern border of the Tibetan plateau) constitutes a tectonically active region as demonstrated by the occurrence of the unexpected 2008 Mw 7.9 Wenchuan and 2013 Mw 6.6 Lushan earthquakes in the central and southern parts of the belt respectively. These events revealed the necessity of a better understanding of the long‐term geological evolution of the belt and its effect on the present dynamics and crustal structure. New structural and thermobarometric data offer a comprehensive dataset of the paleo‐temperatures across the belt and P‐T estimates for low‐grade metamorphic domains. In the central Longmen Shan, two metamorphic jumps of 150‐200°C, 5‐6 kbar and ~50 °C, 3‐5 kbar acquired during the Early Mesozoic are observed across the Wenchuan and Beichuan faults respectively, attesting to their thrusting movement and unrevealing a major decollement between the allochtonous Songpan‐Garze metasedimentary cover (at T > 500°C) and the autochtonous units and the basement (T < 400°C). In the southern Longmen Shan, the only greenschist‐facies metamorphism is observed both in the basement (360 ± 30°C, 6 ± 2 kbar) and in the metasedimentary cover (350 ± 30°C, 3 ± 1 kbar). Peak conditions were reached at c. 80‐60 Ma in the basement and c. 55‐33 Ma in the cover, c. 50 Ma after the greenschist‐facies metamorphic overprint observed in the central Longmen Shan (c. 150‐120 Ma). This along‐strike metamorphic segmentation coincides well with the present fault segmentation and reveals that the central and southern Longmen Shan experienced different tectono‐metamorphic histories since the Mesozoic

A lanthanum picrate complex of a 1,2-bisamide substituted calix[4]arene

The synthesis and structural characterization of a lanthanum picrate complex of the proximally-substituted calix[4]arene bisamide, 5,11,17,23-tetra-tert-butyl-25,26- bis(diethylcarbamoylmethoxy)-27,28-dihydroxycalix[4] arene (L), is reported. The complex is formulated as [La(L-H)(picrate)2]2.75CH2Cl2 and crystallises with two inequivalent metal complexes in the unit cell. The differing dispositions of the picrate anions in the two complexes suggest that intramolecular interactions between the aromatic rings of the picrate and calixarene are less significant than the forces involved in the crystal packing of the complexes