A versatile synthesis of a new bisiminophosphorane

The iminophosphorane CH₂CH₂[P{NP(O)(OPh)₂}Ph₂]₂ is synthesized in high yields (80–97%) via a very convenient procedure using diphenylphosphoryl azide (DPPA) and 1,2-bis(diphenylphosphino)ethane.     

A new family of octanuclear Mn complexes with a rod-like topology

Three new octanuclear compounds were prepared from reactions of [Mn(O₂CR)₂]·2H₂O (R = Et or Ph) with the diols 1,3-propanediol (pdH₂) or 2-methyl-1,3-propanediol (mpdH₂) in the presence of NaN₃. All three compounds [Mn₈(N₃)₄(O₂CR)₆(L)₄(py)₆] (L = pd²⁻, R = Et 1; L = mpd²⁻, R = Et 2; L = pd²⁻, R = Ph 3) (py = pyridine) possess a novel near-planar, rod-like topology. Dc and ac magnetic susceptibility studies in the 2–300 K range for complexes 1 and 2 revealed the presence of dominant antiferromagnetic exchange interactions, leading to diamagnetic ground spin states.     

A new polymorph of dichloridotriphenylantimony

In a new polymorphic form of dichloridotriphenylantimony, [Sb(C₆H₅)₃Cl₂], there are two crystallographically unique molecules in the asymmetric unit and it has been determined that this polymorph is one of two kinetically favoured phases of pure dichloridotriphenylantimony, both of which have Z′ > 1. A third polymorph, corresponding to (C₆H₅)₃SbCl_1.8F_0.2, is also known and has Z′ = 2. By contrast, the thermodynamically preferred polymorph of pure (C₆H₅)₃SbCl₂ has Z′ = 1. A brief comparison of the known polymorphic forms of dichloridotriphenylantimony is presented.     

A new organically-templated cobalt borophosphate with a novel borophosphatic anionic partial structure

A novel cobalt borophosphate, (NH₄)₂(C₄H₁₂N₂)[Co₂B₄P₆O₂₄(OH)₂]·H₂O with the mixed cations has been synthesized under mild hydrothermal conditions. Its crystal structure was determined by the single-crystal X-ray diffraction (tetragonal, I4₁/a (no. 88), a=14.207(3) Å, c=24.956(6) Å, V=5037.09(2) Å³, Z=8). The crystal structure consists of a new type of three-dimensional borophosphatic anionic partial framework, which is built from the condensation of the fundamental building unit (FBU) [B₂P₃O₁₄(OH)]. The CoO₆ octahedra are enchased in such borophosphate network to form a complex open framework with a three-dimensional intersecting channel system, the voids of which are occupied by ammonium, dipronated piperazine ions and water molecules, respectively. The magnetic measurement of the title compound has also been investigated.     

A new flavone C-glycoside and a new bibenzyl from Bulbophyllum retusiusculum

A new flavone C-glycoside, apigenin 6-C-α-arabinofuranosyl 8-C-α-arabinopyranoside (1) and a new bibenzyl, bulbotetusine (2), were isolated from the tubers of Bulbophyllum retusiusculum. Their structures were established on the basis of extensive spectroscopic analyses. The absolute configuration of 2 was determined by the comparison of experimental and calculated electronic circular dichroism. Compounds 1 and 2 showed no obvious cytotoxic activity against any five human tumour cell lines with IC₅₀ values >40 μM.     

Graph factorization: A new mode of application of a vertex-alternation scheme

Linear chains where the vertex weights change sign alternantly but are equal in magnitude were able to be reduced to smaller chains by a procedure analogous to that given by Coulson and Rushbrooke. The algorithm for constructing the reduced chains has been stated and proved. The results have been utilized, in conjunction with McClelland's graph-factorization method using reflection (σ) planes, to reduce the HMO secular determinants of some chemical graphs to an extent beyond the ability of group theory. McClelland's σ-plane algorithm, used repetitively where possible, produces factors whose sizes (n_M) are equal to those (n_G) of the group-theoretic factor blocks. For linear polyacenes (LP ), however, a new observation has been made: If the LP has an even number of fused rings, n_M = n_G; but when the LP has an odd number of fused rings, McClelland's process is effective in further reduction, i.e., n_M < n_G. In any case, however, the vertex alternation procedure reported in the present paper brings about further reduction. To demonstrate the utility of the present method, a sample calculation of the LUMO eigenvector graph theoretically has been shown for p-benzoquinone and the result has been utilized to obtain an inductive effect HMO parameter of the methyl group from the charge-transfer bands of some molecular complexes of methylated p-benzoquinones.© 1993 John Wiley & Sons, Inc.     

A new polymorph of physcion

The structure of the title compound, 7‐methoxy‐2‐methyl‐4,5‐dihydroxyanthracene‐9,10‐dione, C₁₆H₁₂O₅, was originally reported by Ulickýet al. [Acta Cryst. (1991). C 47 , 1879–1881] in the space group P2₁2₁2₁ [polymorph (Io)]. The new polymorph, (Im), crystallizes in the space group P2₁/c. The molecular structures are closely similar, with both –OH groups forming intramolecular hydrogen bonds to one of the neighbouring quinone O atoms, thus slightly lengthening this C=O bond; the pattern of C—C bond lengths in the ring system is consistent with some contribution from a resonance form with a negative charge at the hydrogen‐bonded quinone O atom and an aromatic region around its neighbouring C atoms. The packing of (Im) is simpler than the extensively crosslinked pattern of (Io), with molecular tapes connected by classical (but three‐centre) and `weak' hydrogen bonds, parallel to [20].     

A new carbonylhydridorhenium cluster

The preparation and properties of new polynuclear carbonylhydrido complexes (NEt₄)₃[H₄Re₄(OCH₃)(CO)₁₆] (I) and (NEt₄)₂[H₄Re₄(CO)₁₅] (II) are reported. Infrared and NMR spectra of these compounds are presented and discussed. The structure of compound II has been established by X-ray crystallographic analysis.     

A new calcium trimellitate coordination polymer with a chain-like structure

The calcium trimellitate, Ca(H₂O)[(O₂C)₂–C₆H₃–CO₂H], was hydrothermally synthesized from a mixture of calcium hydroxide, 1,2,4-benzenetricarboxylic (or trimellitic) acid and water at 180 °C for 24 h (under autogenous pressure). Its crystal structure has been determined by single-crystal X-ray diffraction analysis using synchrotron radiation (station 9.8, SRS Daresbury, UK). It consists of infinite chains of calcium bicapped trigonal prismatic polyhedra connected to each other through the 1,2,4-benzenetricarboxylate ligand. The eight-fold coordinated calcium cation is bonded to one terminal water molecule, two carboxylate groups with a chelating conformation and three carboxylate groups in a monodentating mode. One of the monodentate carboxylate is terminal with the occurrence of protonated C–OH bonding.Triclinic space group P-1 with a = 6.9073(4) Å, b = 6.9917(4) Å, c = 10.3561(6) Å, α = 87.178(1)°, β = 83.233(1)°, γ = 69.576(1)°, V = 465.41(5) Å³.     

A new photoproduct of 5-methylcytosine and adenine: a theoretical study

Both the cycloaddition mechanism of 5-methylcytosine with adenine and the deamination mechanism of the cycloaddition product have been studied using density functional theory method. The results suggest that the cycloaddition reaction could occur more easily through photochemical reaction pathway than through thermal reaction pathway. The obtained four-member ring structure could be easily transformed to an eight-member ring structure through bond cleavage of C₅–C₆ (the energy barrier is <2 kcal/mol). Then hydrolytic deamination reaction takes place with water assistance. The hydroxyl group of one water molecule attacks the C₄^′ atom and the hydrogen atom of another water molecule attacks N₃^′ atom to form a tetrahedral intermediate. Subsequently, the hydrogen atom of hydroxyl group transfers to N₈^′ to produce ammonia, and the amino group of the former 5-methylcytosine changes to carboxyl oxygen. Our calculations explain the phenomena that 5-methylcytosine and adenine could obtain the same photoproduct as thymine and adenine from theoretical aspects.     

A new transition point of polyacrylonitrile

A polyacrylonitrile sample of molecular weight 78,000 was dissolved into a 15% solution in 70% aqueous HNO₃, spun into an undrawn model filament with diameter 0.3 mm. using a 30% aqueous HNO₃ as the coagulation bath. The fresh filament was drawn 4–16× in water at various temperatures (40, 65, and 75°C.) and then steamed at 90–180°C. Dynamic mechanical tests were carried out on these filaments at 138 cps and it was found that the steamed filaments had a new transition at about 160°C. in addition to the two well-known transitions at 60–70°C. (β) and 110°C. (α_a), although the unsteamed samples had only the two absorptions, α_a and β. This newly found transition was designated α_x. The α_x was measured at 3.5, 11, and 110 cps from which the activation energy of this relaxational motion was estimated to be 95 kcal./mole. The α_x peak height was lowered by stretching and recovered on resteaming; the change in the peak height was paralleled by the changes in the x-ray crystallinity produced by the stretching and the resteaming. These phenomena lead us to a conclusion that the region contributing to the α_x absorption is of considerably higher order than that of the α_a transition with an activation energy about 50 kcal./mole and intimately related to the crystallinity, although it cannot be connected directly to the crystalline region itself because a single crystal mat did not show the α_x.     

A new polymorph of tetraphenyldiboroxane

A new polymorph of tetraphenyldiboroxane [or oxybis(diphenylborane)], C₂₄H₂₀B₂O, (Ia), has been found. It is monoclinic, like the already known form, (Ib), and can be refined in the same space group, namely P2₁/c, or in the equivalent setting P2₁/n. The molecular conformations of the two polymorphs differ in the rotations of two of the phenyl rings about the B—C bonds, leading to markedly different packing patterns and cell dimensions.     

The crystal structure of a new diterpene lactone—chilobolide A

Chilobolide A, C₂₂H₃₀O₅, M.W. = 374,5, orthorhombic, space group P 2,2,2₁, a = 8.753 (2), b = 8.887 (3), c = 54.247 (14) Å, V = 4220(2) ų, Z = 8, D_x = 1.17 g·cm^?3, F(000) = 1616 e at room temperature. The structure was solved by direct methods with diffractometer data measured with Cu Kα radiation, and block-full-matrix least-squares refinement converged at R = 0.064 for 1805 observed reflections. Both molecules in an asymmetric unit have similar conformation. The molecular skeleton is bicyclic system, in which an envelope form γ-lactone ring is cis-fused to a cyclotridecadiene ring, the latter ring is in [?+?+?++++?+??] asymmetric conformation; the methyl groups attached to 4-C and 13-C are situated on E-type double bond, the acetyl group is in equatorial orientation at 10-C and the acetoxy group is in axial at 9-C.     

A new polymorph of phenylselenium trichloride

A second polymorph of phenylselenium trichloride, PhSeCl₃ or C₆H₅Cl₃Se, is disclosed, which is comprised of asymmetric chlorine‐bridged noncovalent dimer units rather than polymeric chains. These dimers are each weakly bound to an adjacent dimer through noncovalent Se…Cl bonding interactions. Phenyl rings within each dimer are oriented in a syn fashion. Density functional theory (DFT) calculations reveal that the putative anti isomer is within 5 kJ mol^?1 of the experimentally observed form. This structure represents the first additional polymorph discovered for an organoselenium trihalide compound.     

A new ruthenium-catalyzed cyclopropanation of alkenes using propargylic acetates as a precursor of vinylcarbenoids

[RuCl₂(CO)₃]₂ catalyzes intermolecular cyclopropanation of various alkenes with propargylic acetates to give vinylcycloropanes in good yields. The key intermediate of this reaction is a vinylcarbene complex generated by nucleophilic attack of the carbonyl oxygen of the acetate to an internal carbon of alkyne activated by the ruthenium complex.     

A new class of organometallic compound

Summary Organometallic compounds of general formula (SCN)₂M(NCSeHgR)₂ (M=Co^II, Ni^II, R=n-C₅H₁₁,i-C₅H₁₁) have been prepared. They behave as Lewis acids, forming complexes with pyridine and 2,2-bipyridyl, characterized by elemental analysis, molecular weight, molar conductance, i.r. spectral (4000–200 cm^–1), electronic spectral and magnetic susceptibility measurements. The Lewis acids are monomeric with bridging thiocyanate, or selenocyanate between M²⁺ and Hg²⁺. Cobalt and nickel acquire tetrahedral and octahedral configurations respectively through axial bridging, whereas mercury retains its linearity. Pyridine links to the metal in the Lewis acid and forms L₂(SCN)₂M(NCSeHgR)₂ complexes. Bipyridyl ruptures the NCX bridge and forms cationic-anionic [M(bipy)₃][(NCS)(NCSe)HgR]₂ complexes.     

A new stable perfluoroalkyl radical

Conclusions The radiolysis of perfluoro-4-methyl-2-pentene gives a stable radical whose ESR spectrum corresponds to (CF₃)₂CFFCF(CF₃)₂.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1667–1669, July, 1985.The authors express their gratitude to Yu. L. Bakhmutov for assistance in this work.     

Noralashinol A,a new norlignan from stem barks of Syringa pinnatifolia

One new norlignan, namely noralashinol A (1), one known analogue (2), together with seven known lignans (3–9) were isolated from the stem barks of Syringa pinnatifolia. Their structures were elucidated extensively by spectroscopic methods, including mass spectrometry and 1D and 2D NMR spectroscopies. Compound 8 significantly inhibited NO production in LPS-induced BV-2 murine microglia cells with its IC₅₀ value of 20.7 μM, compared to a positive control quercetin with its IC₅₀ value of 15.3 μM.     

A new layered iron fluorophosphate

A new iron fluorophosphate of the composition, [C₆N₄H₂₁] [Fe₂F₂(HPO₄)₃][H₂PO₄]·2H₂O,I has been prepared by the hydrothermal route. This compound contains iron fluorophosphate layers and the H₂PO₄ ^- anions are present in the interlayer space along with the protonated amine and water molecules. The compound crystallizes in the monoclinic space group P2₁/c.(a = 13.4422(10) ?,b = 9.7320(10) ?, c = 18.3123(3) ?, β= 92.1480°,V= 2393.92(5) ?³, Z = 4,M = 719.92,d _calc. = 1.997 g cm^-3, R₁ = 0.03 andwR ₂= 0.09).     

A new spectral memory of filled rubbers

We recently discovered that shearing particle‐reinforced rubbers in oscillation at a frequency f_a at a small strain γ_a (e.g., ～1% strain) for time t_a can often produce a spectrum hole or drop in the strain‐dependent dissipation spectra of the materials. The location of the hole (or localized perturbation in the loss modulus or loss tangent) depends on the aging strain amplitude γ_a. The depth of this hole is influenced by both the oscillatory aging frequency f_a and the aging duration t_a, and follows a simple power relationship of the product of f_a and t_a. The exponent for the power relationship is a function of filler concentration. These attributes of the spectral hole in filled rubbers are not sensitive to the frequency used to postanalyze the hole. This new memory effect occurs at very small strains and involves material stiffening during the strain aging, and both of those features are quite different from the Mullins effect in filled elastomers. We interpret this newly discovered memory character of filled rubbers from a much broader concept of structure pinning in a condensed frustrated system and consider that the agglomeration of filler particles in rubber matrix shares common physics with granular materials and glass‐forming materials. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 859–869, 2010