DENSITY, EQUILIBRIUM HEAT OF FUSION AND EQUILIBRIUM MELTING TEMPERATURE OF NYLON 1010

The density, equilibrium heat of fusion and equilibrium melting temperature of Nylon 1010 were determined by means of infrared spectrum, differential scanning calorimetry, wide angle X-ray diffraction and density measurement techniques. According to Starkweatber' s method crystalline density ρ_c and amorphous density ρ_a were estimated to be 1.098 and 1.003 g/cm~3 respectively by extrapolating the straight lines of the IR absorbanee against density to zero intensity. Owing to the less intense in absorbance and less sensitive to the change in crystallinity of the amorphors band the thus obtained ρ_c was too low in value. Thereby the value of the ratio ρ_c /ρ_a is far less than generally accepted mean value for most crystalline polymers. Accordingly, traditional X-ray diffraction method was used through determining thc crystalline dimension(a=4.9, b=5.4, c=27.8, α=49°β=77.0°, γ=63.5°), and a rather correct value of ρ_c or the crystal density 1.13 g/cm~3 was obtained. The equilibrium heat of fusion △H_m~0 was estimated to be 244.0 J/g piotting △H_m 's of specimens with different crystallinity against their corre sponding specific volumes _(sp), and extrapolating to completely crystalline condition (_(sp)~c= 1/ρ_c) As to the equilibrium melting temperature T_m~0, because of the easiness of recrystallization of melt crystallized Nylon 1010 specimen, the well-known Hoffman's T_m-T_c method failed in determining this value and an usually rarely used Kamide double extrapolation method was adopted. The so obtained value of T_m~0 487 seems to be fairly reasonable.     

The heat of fusion of polytetrafluoroethylene

The heat of fusion of virgin and melt-processed polytetrafluoroethylene (PTFE) was determined using the Clapeyron equation. Experimental data were obtained from PVT experiments and high-temperature x-ray diffraction measurements. For virgin, as-polymerized PTFE, the melting temperature is given by where, for T_m in degrees Celsius, A = 346.3±1.2, B = 0.095±0.003, and P is the pressure in kilograms per square centimeter. At the end of the atmospheric-pressure melting interval, the amorphous and crystalline specific volumes V₁ and V_c are 0.6517 and 0.492 cm³/g, respectively. Thus the heat of fusion is 24.4 cal/g, or nearly twice the value reported previously. The increases in enthalpy and volume at the melting point both indicate a degree of crystallinity of about 75–80% although infrared, x-ray, and NMR data give much higher levels. Data from calorimetry, NMR, and dynamic mechanical measurements indicate that in virgin PTFE some of the crystals continue to experience torsional oscillations at temperatures below the room-temperature transitions. This indicates that there are at least two kinds of crystalline regions. For previously melted PTFE, T_m is determined by A = 328.5±0.7 and B = 0.095±0.002, the volumes are V_am = 0.6349 and V_cr = 0.4855 cm³/g, and the heat of fusion is 22.2 cal/g. The entropy of fusion for PTFE is much closer to that of polyethylene than was previously believed.     

The Missing Link in Low Nuclearity Pure Polyoxovanadate Clusters: Preliminary Synthesis and Structural Analysis of a New {V16} Cluster and Related Products

Two new metastable polyoxovanadate-based cluster compounds have been isolated and crystallographically characterized with nuclearities of {V₁₆} (1) and {V₁₈} (2). The {V₁₆} cluster represents a new framework type and incorporates two protons into the cluster framework whereas the {V₁₈} framework has been previously characterised, and the oxidation states of the {V₁₈} cluster can be assigned as {V^IV ₁₅V^V ₃}. Compound K₁₀[H₂V₁₆O₃₈]13H₂O (1) crystallizes in the monoclinic space group P2₁/c, a=12.12820(10), b=38.2302(3), c=12.35400(10) Å, =115.0470(10)°, V=5189.43(7) ų, D _c=2.624 gcm^–3. 10086 unique reflection and 702 refined parameters were used in structure refinement. R1=0.039, R2=0.109 (all data). From the same preparation the new compound K₁₁[V₁₈O₄₂(SO₄)]20H₂O (2) was also isolated and crystallographically characterized. Compound 2 crystallizes in the monoclinic space group P2₁/n, a=12.7854(3), b=20.2812(5), c=13.2386(4) Å, =115.3400(10)°, V=3102.53(14) ų, D _c=2.650 gcm^–3. 7115 unique reflections and 462 refined parameters were used in structure refinement. R1=0.046, R2=0.121 (all data).     

Natural product chemistry,part 100: The structure of carissone,C15H24O2

Summary C₁₅H₂₄O₂,M=236.2, monoclinic, P 2₁,a=7.229(7),b=14.925 (9),c=6.235 (9) Å, =92.40 (9)°,V=672.1 ų,T=–133 °C,Z=2,D _x=1.17 g cm^–3. The X-ray diffraction analysis of this sesquiterpenoid fromCarissa opaca confirmed the previously proposed constitution of the isolate and, furthermore, allowed precise NMR assignment.

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Naturstoffchemie, 100. Mitt.: Die Struktur des Carissons, C₁₅H₂₄O₂

Zusammenfassung C₁₅H₂₄O₂,M=236.2, monoklin, P 2₁,a=7.229 (7),b=14.925 (9),c=6.235 (9) Å, =92.40 (9)°,V=672.1 ų,T=–133 °C,Z=2,D _x=1.17 g cm^–3. Die Röntgenstrukturanalyse dieses Sesquiterpenoids ausCarissa opaca bestätigte die bereits vorgeschlagene Struktur und erlaubte ferner eine genaue NMR-Zuordnung.

     

Structural study of the 1:1 clathrate of an asymmetric calix[4]arene and acetone

The crystal and molecular structure of the 1:1 clathrate of the asymmetric calix[4]arene,1, and acetone has been determined by X-ray analysis. The crystal data are: tetragonal, space groupP4/n,a=b=12.574(6),c=12.572(6) Å,V=1988(2) ų,Z=2,D _x =1.111 g cm^–3,D _m =1.108 g cm^–3. Least-squares refinement based on 1131 observed reflections withF ₀>3(F ₀) and anisotropic temperature factors led toR=0.096. In spite of the molecular asymmetric calixarene1 the crystal structure has high symmetry, because a part of the host and guest molecules are in disordered states.     

Reactions of 2H-3,4-dihydro-1,4-benzoxazin-6(8aH)-ones with 2,4,6-trimethylbenzonitrile oxide,III

Summary Regio-, stereo- and siteselectivity of the cycloadditions of trimethylbenzonitrile oxide with 2H-3,4-Dihydro-1,4-benzoxazin-6(8aH)-ones have been investigated. The structures of the obtained products were elucidated by means of homonuclear NOE difference spectroscopy and HMQC and HMBC spectra. The structure of 6-Benzyl-9a-methoxy-3-mesityl-9b-methyl-7,8,9a,9b-tetrahydro-3aH-1,2-oxazolo-[4,5-h]1,4-benzoxazin-4(6H)-on5 was elucidated from a single crystal X-ray structure analysis at ambient temperature: C₂₇H₃₀N₂O₄, M=446.55g/mol, monoclinic, P2₁/c,a=10.372 (34) Å,b=11.908 (21) Å,c=20.040 (34) Å, =97.16 (17)°,V=2455.8 (1.9)ų,Z=4,d _c=1.208g/cm³, =0.08mm^–1,R=0.0546.Dedicated to Prof. Ott with best wishes for his 70^th birthday     

STRUCTURAL CHARACTERIZATION OF POLYETHYLENES BY DSC ANALYSIS AFTER CRYSTALLIZATION SEGREGATION*

The molecular structure of polyethylene (PE) samples with various comonomers including propylene, 1-buteneand 1-hexene was investigated by DSC and ~(13)C-NMR techniques. The density of the samples varies from 0.948 g/cm~3 to0.917 g/cm~3, and the molecular weight determined by the GPC method is in the range of 1～2×10~5. The branch point contentof the samples was determined by ~(13)C-NMR measurements and was found to be less than 20 per 1000 C atoms along themain chain. Crystallization segregation DSC technique (CSDSC) was used to characterize the branch point distribution or thesegment length distribution of PEs. The crystallization segregation was performed in a successive annealing process atdecreasing temperatures. The interval of two successive annealing temperatures was 6 K, and the time length of eachannealing step was 2.5 h. The CSDSC results clearly indicate that all the PE samples used, including some metallocene PEs,more or less exhibit their non-uniformity in segment length distribution, and bimodal or multimodal CSDSC curves wereusually observed. For quantitative characterization of the CSDSC curves and the segment length distribution two parameters,the average melting point, T_(mAV), and the root-mean-square deviation of melting temperature, (ΔT_(mAV)~2)~(1/2), were proposed.T_(mAV) is corresponding to the average segment length due to branching and (ΔT_(mAV)~2)~(1/2) gives information about the width ofthe segment length distribution. Experimental results show that both the degree of average melting temperature depressionand the width of the distribution seem to increase with increasing the branching content and are dependent on the type ofcomonomers. Very good reproducibility and additivity of the CSDSC method were evidenced experimentally. It wasconcluded that the CSDSC technique is a sensitive and convenient method for characterizing the segment length distribution of branched polyethylenes and will be of great interest in structure-property relationship studies of crystalline polymers.     

Two clathrates of bis(isothiocyanato)tetrakis(4-methylpyridine)magnesium(II) as a host with 4-methylpyridine as a guest

Two clathrate modifications of the title host with 4-methylpyridine (4-CH₃C₅H₄N) as a guest have been determined at –50°C. [Mg(4-CH₃C₅H₄N)₄(NCS)₂] · 2/3(4-CH₃C₅H₄N) · 1/3H₂O is trigonal, space group , witha=27.630(7),c=11.219(3) ÅV=7417(4) ų,Z=9,D _calc=1.171 g cm^–3,(CuK )=18.506 cm^–1, finalR=0.064. [Mg(4-CH₃C₅H₄N)₄(NCS)₂] · (4-CH₃C₅H₄N) is tetragonal, space group I4_l/a, witha=16.944(7),c=23.552(9)Å,V=6762(5) Å,Z=8,D _calc=1.191 g cm^–3, (CuK )=18.200 cm^–1, finalR=0.071.The structures consist of molecular packings of the same host complex units and the guest species. The Mg(II) cation is octahedrally coordinated to theN-atoms of four 4-methylpyridine and twotrans-coordinated isothiocyanato ligands in the host molecule. The conformations of the molecule are considerably different both in symmetry and in geometry in these two structures. The guest 4-methylpyridine molecules are disordered into channels which have different topology in these two clathrates resulting in different thermal stability.     

1,2-Oxazoline durch Addition von Trimethylbenzonitriloxid an 2-Hydroxyethylamino-1,4-benzochinone und deren Chinolderivate

Summary Addition of trimethylbenzonitril oxide to 2-hydroxyethylamino-1,4-quinones and 3,4-dihydro-4-alkyl-8a-methoxy-2H-1,4-benzoxazin-6(8aH)-ones leads to 7,8,9a,9b-tetrahydro-3aH-1,2-oxazolo[4,5-h]-1,4-benzoxazin-4(6H)-ones. In order to determine constitution and conformation of the addition products an NMR-spectroscopic analysis and an X-ray crystal structure analysis of 6-benzyl-9a-hydroxy-3-mesityl-7,8,9a,9b-tetrahydro-3aH-1,2-oxazolo[4,5-h]-31,4-benzoxazin-4-(6H)-one3a were carried out at room temperature: C₂₅H₂₆N₂O₄,M _r=418.49, monoclinic, P2₁/n,a=13.716(6),b=19.993(6),c=15.348(6) Å, = 98.55(4)°,V=4162(1)ų,Z=8,d _x=1.336g/cm³,R=6.77%,R _w=4.55% (2994 observables, 560 parameters).

     

希夫碱配合物的研究——Ⅵ.K[Fe(acaccn)(CN)2]·2H2O的合成及晶体结构

制备了K[Fe(acaccn)(CN)₂]·2H₂O.并测定了晶体结构.     

One Novel Vanadium-Phosphate Cluster [PV_(2.5)O_(8.5)]-3.83{H_2O} with Three-Dimensional Architecture

A novel vanadium-phosphate compound [PV_2.5O_8.5]·3.83{H_2O}(1)was obtained from the hydrothermal reac-tion and structurally characterized by elemental analysis and single-crystal X-ray diffraction,which exhibited thatthe title complex crystallized in cubic space group I-43m with crystal data:a=1.6115(1)nm,V=4.1848(1)nm~3,Z=12,D_c=1.783 g/cm~3,F(000)=2278,R_1=0.0528,and wR_2=0.1329[I>2σ(I)](all data).The basic unit of{PV_2.5O_8.5}symmetrically extended to closed sphere-like structure of{P_4V_(10)O_(34)},which was further linked to in-terleaving three-dimensional network via sharing four phosphate through μ_3-oxygen atoms around the closedsphere-like structures.     

Zur Umsetzung von 8a-Methoxy-3,4-dihydro-2H-1,4-benzoxazin-6(8aH)-onen mit Diazoalkanen, 2. Mitt.

Summary 8a-Methoxy-3,4-dihydro-2H-1,4-benzoxazin-6(8aH)-ones2 undergo regio- and stereospecific 1,3-dipolar cycloaddition reactions with diazomethane or diazoethane to yield 3,4,6a,9,9a,9b-hexahydro-pyrazolo[3,4-h][1,4]benzoxazin-6(2H)-ones3, which slowly isomerize in solution to give the 3,4,8,9,9a,9b-hexahydro-pyrazolo[3,4-h][1,4]benzoxazin-6(2H)-ones5. The carbon of the diazoalkane dipole is attached to carbon C-8 of the benzoxazinone. The structures of the obtained products were determined by¹H- and¹³C-NMR spectroscopy. An X-ray crystal structure analysis of3 a was carried out at room temperature:C₁₁H₁₅N₃O₃,M _r =237.26, orthorhombic, Pc2₁n,a=9.173 (5),b=9.133 (4),c=13.281 (6),V=1112.6 (9) ų,Z=4,d _x =1.416 g/cm^–3, =0.93 cm^–1,R=4.33%,R _w =3.95% (919 observations, 168 parameters).

Herrn Prof. Dr. W. Fleischhacker zum 60. Geburtstag gewidmet     

New Layered Materials in the K–In–Ge–As System: K8In8Ge5As17and K5In5Ge5As14

Exploratory synthesis in the K–In–Ge–As system has yielded the unusual layered compounds K₈In₈Ge₅As₁₇(1) and K₅In₅Ge₅As₁₄(2), both of which contain In–Ge–As layers with interleaved potassium ions, Ge–Ge bonds, InAs₄tetrahedra, As–As bonds, and rows of Ge₂As₆dimers. Compound 1 has As₃groups, while compound 2 has infinite As ribbons on both faces of each layer. Unlike compound 1, compound 2 has substitutional defects where indium partially occupies each of the three independent germanium sites in the ratio of 1:5 for In:Ge. This partial occupancy makes 2 an electron-precise compound. The Ge(In)–Ge(In) bond of 2 is longer than the Ge–Ge bond of 1, and this bond lengthening effect was confirmed by performing DFT-MO calculations on the model compounds H₃Ge–GeH₃and H₃Ge–InH⁻₃. Possible implications of electron imprecise formulas determined by X-ray crystal structure determinations are discussed. Compound 1: space groupP2₁/cwitha=18.394 (8) Å,b=19.087 (7) Å,c=25.360 (3) Å,β=105.71 (2)°,V=8571 (4) ų, andD_calcd=4.45g/cm³forZ=4. Refinement on 4455 reflections yieldedR(R_w)=6.8%(7.8%). Compound 2: space groupC2/mwitha=40.00 (1) Å,b=3.925 (2) Å,c=10.299 (3),β=99.97 (2)°,V=1592 (1) ų, andD_calcd= 4.55g/cm³forZ=8. Refinement on 1206 reflections yieldedR(R_w)=5.6% (5.7%).     

m -Terphenyl derivative of titanium(III): Cp2TiR (Cp=C5H5; R =2,6-(4-MeC6H4)2C6H3)

The title compound, Cp₂TiR (Cp=C₅H₅; R=2,6-(4-MeC₆H₄)₂C₆H₃), 1, was prepared by reaction of RLi with [Cp₂TiCl]₂. Compound 1 was characterized by elemental analysis, EPR, and single crystal X-ray crystallography. The title compound crystallizes in the monoclinic space group C2/c with the following unit cell dimensions: a=11.1466(7) Å, b=16.4429(11) Å, c=13.0786(8) Å; b=106.2040(10)^°;V=2301.9(3) ų. The EPR spectrum of 1 displays two signals, a high field signal at g=1.979 and a lower field signal at g=1.959. Significantly, 1 is a sterically encumbered m-terphenyl-stabilized trivalent titanocene paramagnetic complex and may be a practical one-electron reducing reagent.     

Studies on olefin-coordinating transition metal carbene complexes: VI. Synthesis and crystal structure of two novel inner salt complexes of iron

Reaction of N-cinnamylidenyl-m-4-xylidine (tricarbonyl) iron ( 1 ) with phenyllithium and p-chlorophenyllithium at low temperature, and subsequent alkylation of the resulting adducts with Et₃OBF₄ in CH₂Cl₂ at ?60°C gave two novel zwitter-ion iron complexes with the compositions of C₁₉H₂₂ N(CO)₃ FeC₆H₅(2) and C₁₉H₂₂N(CO)FeC₆H₄Cl (3), respectively. The complex 2 crystallizes in the monoclinic system, space group P2₁/_n with a = 10.624(3), b = 25.155(6), c = 19.375(9)Å, β = 101.1 (3)°, V= 5042.2ų, Z=8, D_c = 1.27g/cm³. The structure of 2 has been solved by direct method and refined by block-matrix least-squares method to give the final R of 0.071.     

X-Ray Diffraction Study of Piperidine Octamolybdate

Piperidine octamolybdate [C₅H₅NH₂]₄[Mo₈O₂₆]·4H₂O (I) has been synthesized and characterized by X-ray diffraction analysis. Crystals I are monoclinic, space group P2₁/n, a=12.892(3), b=9.283(2), c=19.184(4) , =92.50(3)°, V=2293.7(9) ³, Z=2,_calc = 2.317 g/cm³.     

两个双核铁（Ⅲ）和三足配体的配合物的合成和晶体结构

运用三足四齿配体三（2－甲基吡啶）胺（TPA）或三（2－甲基苯丙咪唑）胺（TBA）,得到两个双核铁(III)配合物，[Fe₂L₂(μ₂-O)(μ₂-p-NH₂-C₆H₄COO)]³⁺ (L = TPA, 1 和 L = TBA, 2)。两个配合物均为单斜晶系，空间群为P2(1)/c.晶胞参数 1: a = 1.4529(4), b = 1.6622(5), c = 2.0625(6) nm, β= 100.327(5)º, V = 4.900(3) nm³, z = 4, F(000) = 2344, 分子量M_r = 1142.91, Dc = 1.549 g/cm³, R₁ = 0.0544, R₂ = 0.0962. 2: a = 1.3378(4), b = 2.1174(7), c = 2.4351(7) nm, β= 97.315(6)º, V = 6.842(4) nm³, z = 4, F (000) = 3116, 分子量M_r = 1505.08, Dc = 1.444 g/cm³, R₁ = 0.0793, R₂ = 0.1623. 在两个双核铁(III)配合物中，中心的三价铁和配体TPA或TBA上的四个氮原子和两个氧原子通过不同的桥形成一个畸变的八面体构型。     

Cyano-bridged Heterotrinuclear Molybdenum(IV)-Nickel(II) Complexes: Synthesis,Crystal Structure and Magnetic Properties

Two novel cyano-bridged heterotrinuclear molybdenum(IV)-nickel(II) complexes ([Ni(en)₂(H₂O)]_2-[Mo(CN)₈]·2H₂O, 1, and [NiL(H₂O)]₂[Mo(CN)₈]·4H₂O, 2), where en=1,2-diaminoethane and L= 1,3,6,9, 11,14-hexaazacyclo[12,2,1,1^6,9]octodecanne were synthesized and characterized. The crystal structure of 1 was determined. The structure consists of trinuclear units, space group C2/c, with unit cell dimensions a=17.178(9), b=11.032(5), c=17.629(8) Å, α=108.484(8)°. The temperature dependence of the magnetic susceptibilities for 1 and 2 was analyzed by means of a Hamiltonian expression leading to J=-0.87cm^-1, ZJ'=0.65cm^-1, D=0.02cm^-1, g _Ni=2.45 for complex 1, and J=-0.87cm^-1, ZJ'=0.56cm^-1, D=0.02cm^-1, g, _Ni=2.45 for complex 2.     

一种新型螺旋桨状配体构型的锰（N-苯甲醛-N’-水杨酰腙）配合物的合成、晶体结构和生物活性研究

本文合成并表征了一种新型螺旋桨状配体构型的锰配合物,其结构式为[Mn(N’-benzylidenesalicylhydrazide)3(H2O)]。该配合物的晶体结构用X-射线单晶衍射测定。配合物的晶体为三斜晶系,空间群P-1,晶胞参数：a=11.6411Å,b=12.728Å,c=16.346Å,α=110.357°,β=96.555°,γ=108.996°,V=2075.2Å3,Z=2,Dcalc=1.265g/cm3。在该配合物中,金属离子为八面体配位形式,使得三个配体以一种螺旋桨状的立体结构排列在它周围。抗菌活性试验表明,对受试微生物,配合物比配体表现出更强烈的活性。