Cooperative density wave and giant spin gap in the quarter-filled zigzag electron ladder

Strong cooperative interactions occur between four different broken symmetries involving charge ordering and bond distortions in the quarter-filled correlated zigzag electron ladder. The ground state is singlet, with spin gap several times larger than in the spin-Peierls state of the one-dimensional quarter-filled chain with the same parameters. We propose the quarter-filled zigzag electron ladder model for several different organic charge transfer solids with coupled pairs of quasi-one-dimensional stacks, in which the spin-gap transition temperatures are unusually high.     

Structure of 6-aminobenzofuran-2-sulfonamide: A tropically active carbonic anhydrase inhibitor

Crystals of the title compound are triclinic. Space groupP1,a=8.652(2),b=5.184(2),c=5.050(2)Å,=100.26(3)°,=100.33(4)°, =72.82(3)°. The structure was solved by direct methods and refined by a full-matrix, least-squares procedure toR=0.033 for 1168 observed [I >2(I)] reflections. The sulfonamide group is at a right angle to the benzofuran ring and the dihedral angle between the benzene and furan ring is 2.0(1)°. In the crystal packing the molecules are linked together by N-HO and N-HN type hydrogen bonds arranging themselves in such a way that there are alternate hydrophobic and hydrophilic regions extended along the a-axis.     

Crystal and molecular structure and absolute configuration of Withaperuvin E: a C28 steroidal lactone

The withanolide Withaperuvin E, C₂₈H₃₆O₈, has been obtained from the air dried roots of Physalis peruviana and purified by silica gel chromatography. This compound exhibits significant antineo plastic activity. Prismatic pale yellow crystals were obtained from a methanol/acetone solution. The compound crystallizes together with a partially occupied [40(1)%] acetic acid molecule, in space group P2₁2₁2₁, Z = 4, D _c = 1.242 g cm^–3, with unit, cell parameters a = 11.431(3), b = 14.104(1), c = 17.387(5)Å, V = 2803.2(11)ų, and (CuK) = 0.072mm^–1. Through the X-ray analysis the molecule was found to be comprised of a steroidal skeleton with a -oriented oxygen bridging atoms C(5) and C(6) in ring B. Steroid ring conformations are: A sofa; B sofa; C chair; D intermediate half-chair/sofa; the lactone ring E has a sofa conformation. All rings of the steroid skeleton are trans connected. The absolute configuration of the Withaperuvin E skeleton corresponds to that of naturally occurring steroids, C(18) and C(19) both being -oriented. The partially occupied acetic acid molecule forms a hydrogen bond to the steroid molecule. Hydrogen bonding also occurs between OH(14) and a symmetry related oxygen O(20) of the steroid.     

A Review of the Synthesis and Utility of Some Lipopathic Permanganate Oxidants

Permanganate, the versatile oxidizing agent, has limited solubility in non-polar media, which limits its use for oxidation of organic substrate in the non-aqueous media. But the combination of PTCs with permanganate makes it mild, selective and lipopathic. These lipopathic oxidants are useful for many important organic transformations. In this communication, we have presented the synthesis and utility of some selected lipopathic permanganate oxidants, which oxidize many functional groups, including alcohol, aldehyde, ether, alkane, alkene, alkyne, and oxime and have use in many synthetic organic procedures with chemo-, regio- and stereoselectivity.     

Crystal and molecular structure of 6-chloro-3-cyclopentylmethyl-3,4-dihydro-7-sulfamyl-2H-1,2,4-benzothiadiazine-1,1-dioxide

The crystal structure of the title compound, C₁₃H₁₈N₃O₄S₂C1, a sulfa drug, has been determined by X-ray diffraction data using MoK radiation. The crystals are orthorhombic,Pbca, witha=9.441(4),b=29.633(11),c=12.167(8) Å andZ=8. The structure was solved by the heavy-atom method, and refined by full matrix least-squares to a finalR value of 0.054 with 2062 observed reflections. In the crystal, the molecules are linked by N-HO hydrogen bonds.     

Crystal and molecular structure of 4-(N,N-dimethylamino) benzaldehyde thiosemicarbazone

4-(N,N-Dimethylamino)benzaldehyde thiosemicarbazone, C₁₀H₁₄N₄S, has been prepared. The crystal structure has been determined from X-ray diffractometer data byMultan 78. The crystals are triclinic:P¯1,a=8.532(1),b=9.391(1),c=15.592(4) Å,=73.81(2),=79.59(2), =82.85(2)°,Z=4, finalR=0.033 for 2198 observed reflections. Atomic charge densities have been calculated by the CNDO/2 method. The S and hydrazinic N atoms in both molecules in the asymmetric unit are in thetrans configuration. The crystal structure is stabilized by N-HS hydrogen bonds. The net negative charge on the hydrazinic N atom, calculated by the CNDO/2 method, is decreased as compared to those in some 4-phenylthiosemicarbazide derivatives.     

Quantum normal form and the harmonic oscillator withx 6 perturbation

The eigenvalue problem of the harmonic oscillator with thex ⁶ perturbation,H=1/2(p ²+x ²+x ⁶), is investigated using the method of quantum normal form. The energy eigenvalues are found to be in good agreement with the WKB results.     

Crystal and molecular structure of 3-tert-butyl-1-ethyl-1-[(4-chlorobenzene) sulfonyl] urea

The crystal structure of the title compound, C₁₃H₁₉SN₂O₃Cl, has been solved by direct methods with X-ray diffraction data collected using Cu K radiation. The crystals are monoclinic, witha=9.415(2),b=9.836(3),c=16.928(3)Å,=95.77(3)° and space groupP2₁/c. The structure was refined with 1806 observed [I>2(I)] unique reflections measured on Siemens AED single Crystal diffractometer equipped with a IBM PS2/30 personal computer, to a finalR value of 0.076. The molecule has similar geometrical and conformational features to those observed in 3-tert-butyl-1-methyl-1-[(4-chlorobenzene) sulfonyl] urea (Ghoshet al., 1992) and most of the sulfonamide structures.