Synthesis and characterization of multiferroic BiMn7_7O12_{12}

We report on the high pressure synthesis of BiMn$_7$O$_{12}$, a manganite displaying a "quadruple perovskite" structure. Structural characterization of single crystal samples shows a distorted and asymmetrical coordination around the Bi atom, due to presence of the $6s^{2}$ lone pair, resulting in non-centrosymmetric space group Im, leading to a permanent electrical dipole moment and ferroelectric properties. On the other hand, magnetic characterization reveals antiferromagnetic transitions, in agreement with the isostructural compounds, thus evidencing two intrinsic properties that make BiMn$_7$O$_{12}$ a promising multiferroic material.Comment: 4 pages, 3 figure

Crystallographic disorder and electron scattering on structural two-level systems in ZrAs1.4Se0.5

Single crystals of ZrAs1.4Se0.5 (PbFCl type structure) were grown by chemical vapour transport. While their thermodynamic and transport properties are typical for ordinary metals, the electrical resistivity exhibits a shallow minimum at low temperatures. Application of strong magnetic fields does not influence this anomaly. The minimum of the resistivity in ZrAs1.4Se0.5 apparently originates from interaction between the conduction electrons and structural two-level systems. Significant disorder in the As-Se substructure is inferred from X-ray diffraction and electron microprobe studies

4-Nitro-2-{[(tricyclo­[3.3.1.13,7]decan-1-yl)iminium­yl]meth­yl}phenolate

The title compound, C17H20N2O3, is a Schiff base, which is found as a zwitterion in the solid state. The geometry around the iminium N atom indicates sp 2-hybridization. The zwitterion shows a strong intra­molecular N—H⋯O hydrogen-bond inter­action between the iminium N atom and the phenolate O atom

A new triclinic modification of the pyrochlore-type KOs2O6 superconductor

A new modification of KOs2O6, the representative of a new structural type (Pearson symbol aP18, a=5.5668(1)A, b=6.4519(2)A, c=7.2356(2)A, space group P-1, no.2) was synthesized employing high pressure technique. Its structure was determined by single-crystal X-ray diffraction. The structure can be described as two OsO6 octahedral chains relating to each other through inversion and forming big voids with K atoms inside. Quantum chemical calculations were performed on the novel compound and structurally related cubic compound. High-pressure X-ray study showed that cubic KOs2O6 phase was stable up to 32.5(2) GPa at room temperature.Comment: 23 pages, 9 figures,6 tables. Accepted for J. Solid State Che

1-(4-Bromo-3-chloro­phen­yl)-3-meth­oxy-3-methyl­urea (chlorbromuron)

In the title urea-based herbicide, C9H10BrClN2O2, there exist multiple inter- and intra­molecular inter­actions. Most notably, the intra­molecular hydrogen bond between the urea carbonyl O atom and an aromatic H atom affects the planarity and torsion angles of the mol­ecule by restricting rotations about the Ar—secondary amine N and the secondary amine N and the carbonyl C. The two N atoms in the urea fragment are in different environments. One is planar; the other, pseudo-C 3v. It is likely that the different nitro­gen-atom geometries and the restricted rotations within the mol­ecule impact the bioactivity of chlorbromuron

Diethyl 2-[(1-methyl-1H-pyrrol-2-yl)methyl­ene­amino]-5-(2-thienylmethyl­ene­amino)thio­phene-3,4-dicarboxyl­ate

Both imine bonds of the title compound, C21H21N3O4S2, were found to be in the E configuration. The terminal pyrrole and thio­phene rings are twisted by 2.5 (3) and 2.3 (2)°, respectively, from the mean plane of the central thio­phene to which they are attached. The structure is disordered by exchange of the terminal heterocyclic rings; the site occupancy factors are ca 0.8 and 0.2. The crystal packing involves some π–π stacking [3.449 (4) Å between pyrrole and terminal thio­phene rings]

CRYSTAL AND MOLECULAR-STRUCTURE OF 2',3',5'-TRI-O-ACETYL-6-O-(MESITYLENESULPHONYL)GUANOSINE

The structure of a 6-O-mesitylenesulphonyl derivative of 2',3',5'-tri-O-acetylguanosine, C 24 H 29 N50 10 S, has been determined by X-ray diffraction. Crystals are monoclinic, a = 26.370 (4), b = 8.200 (2), c = 17.991 (3) A, fl = 132.77 (4) o. The solution of the structure in space group C2 was not straightforward and is described in detail. Refinement converged at R = 0.110 for 1102 observed reflections. The guanine base displays some deviations from its usual geometry due to the loss of C(6)-O(6) double-bond character. The ribose sugar is C(2')-endo puckered

2,4-Diiodo-6-{[4-(morpholin-4-yl)phenyl]iminomethyl}phenol

In the title compound, C17H16I2N2O2, the two aromatic rings are almost coplanar [dihedral angle 2.57 (15)°]. The morpholine ring adopts a chair conformation. The mol­ecular structure is stabilized by an O—H⋯N hydrogen bond and the crystal packing exhibits weak inter­molecular C—H⋯O and π–π [centroid-to-centroid distances 3.663 (3)-4.073 (3) Å] inter­actions

4-[(E)-(4-Diethyl­amino-2-hy­droxy­benzyl­idene)amino]-1,5-dimethyl-2-phenyl-1H-pyrazol-3(2H)-one

In the title compound, C22H26N4O2, the phenyl ring and hy­droxy­benzene group are twisted with respect to the central pyrazolone ring, making dihedral angles of 54.05 (5) and 21.80 (6)°, respectively. One of the ethyl groups is disordered over two positions with site occupancies of 0.872 (6) and 0.128 (6). The mol­ecular structure features short intra­molecular O—H⋯N and C—H⋯O contacts. The crystal packing exhibits weak inter­molecular C—H⋯O and C—H⋯π inter­actions

2-Methyl-4,4-dioxo-N-phenyl-5,6-di­hydro-1,4-oxathiine-3-carboxamide (Oxycarboxin)

In the title compound, C12H13NO4S, a systemic fungicide, the heterocycle adopts a lounge chair conformation and the dihedral angle between the ring planes is 25.8 (2)°. Inter­molecular C—H⋯O hydrogen bonds are noted in the crystal structure. Also observed is a short inter­action of a methyl­ene hydrogen atom with the π-electron system of a phenyl ring in an adjacent mol­ecule