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1.
2-Iodoacetamide has been studied by electron diffraction, utilizing a new nozzle construction. A skew conformation with a dihedral angle of 126.3(1.1)° from syn (C-I bond eclipsing the C-N bond), and a gauche conformation with a dihedral angle of 42.3(1.6) both fit the experimental data almost equally well. However, comparison with the X-ray structure and the results for the two models indicate a slight preference for the skew form.The most important structural parameters are: rg(CO) = 1.222(3)Å, rg(C-N) = 1.370(3)Å, rg(C-C) = 1.515(4) Å, rg(C-I) = 2.160(4) Å, ∠αOCC = 120.0(6)°, ∠αNCC = 116.9(4)° and ∠αCCl = 117.3(4)°. Parenthesized values are one standard deviation.  相似文献   

2.
Azidoacetonitrile (azidoethanenitrile) has been synthesized and the structure determined by electron diffraction from the vapour. IR spectra have been recorded of the vapour, liquid, solutions, solid at ca. 90 K and of the molecule trapped in argon and nitrogen matrices at 15 K. Raman spectra of the cooled liquid and of the amorphous and crystalline solids have also been obtained.

The electron diffraction results show the conformation to be gauche around the C---N bond with a dihedral angle of 52°(5) from syn and the NNN angle 173°(3) oriented anti to the C---N bond.

The following bond distances (ra) between the heavy atoms were obtained: rCN = 115.4(5) pm, rC---C = 146.5(15) pm, rC---N = 147.5(6) pm, rN---N = 124.5(5) pm and rNN = 113.5(4) pm.

Very large changes in both frequency and intensity have been observed in the vibrational spectra upon crystallization which may be due to intermolecular associations formed by the azido group but which can also be explained by a change of the molecular conformation from only gauche in the vapour and liquid phases to anti in the crystal phase.  相似文献   


3.
The crystal structures of two new Sc(III) porphyrins, [Sc(TPP)Cl]·2.5(1-chloronaphthalene), (5,10,15,20-tetraphenylporphyrin)-chloro-scandium(III)·2.5(1-chloronaphthalene) solvate, (Mo Kα, 0.71073 Å, triclinic system  = 9.9530(2) Å, b = 15.4040(3) Å, c = 17.7770(3) Å, α = 86.5190(10)°, β = 89.7680(10)°, γ = 86.9720(10)°, 13101 independent reflections, R1 = 0.0712) and the dimeric [μ2-(OH)2(Sc(TPP))2], bis-(μ-hydroxo)-(5,10,15,20-tetraphenylporphyrin) scandium(III) (Mo Kα, 0.71073 Å, monoclinic system C2, a = 24.2555(16) Å, b = 11.1598(7) Å, c = 25.6468(17) Å, β = 91.980(2)°, 13084 independent reflections, R1 = 0.0485) are reported. In [Sc(TPP)Cl] the metal is five-coordinate and the porphyrin is domed with the metal displaced by 0.63 Å from the mean porphyrin towards the axial Cl ligand. The average Sc-N bond length is 2.143(3) Å, which is shorter than the average bond length of previously reported structures. Two of the phenyl rings are nearly orthogonal to the porphyrin core and the other two are significantly tilted because of contacts with 1-chloronaphthalene solvent molecules, and the phenyl rings of neighbouring porphyrins. In [μ2-(OH)2(Sc(TPP))2] both porphyrins are domed, with the metal displaced from the mean porphyrin plane towards the bridging hydroxo ligands. The average Sc-N bond length is 2.197(12) Å, which is in the upper range of Sc-N bond lengths in known Sc(III) porphyrins but not dissimilar to the average Sc-N bond lengths in another other bis-μ2-hydroxo Sc(III) porphyrin, [μ2-(OH)2(Sc(OEP))2]. One porphyrin is rotated relative to the upper porphyrin by 25° due to steric contacts between the phenyl substituents. We have used these new structures to re-evaluated our previously reported molecular mechanics force field parameters for modelling Sc(III) porphyrins using the MM2 force field; the training set was augmented from two to seven structures by using all available Sc(III) porphyrin structures and the two new structures. The modelling reproduces the porphyrin core very accurately; bond lengths are reproduced to within 0.01 Å, bond angles to within 0.5° and torsional angles to within 2°. The optimum parameters for modelling the Sc(III)-N bond lengths, determined by finding the minimum difference between the crystallographic and modelling mean bond lengths with the aid of artificial neural network architectures, were found to be 0.90 ± 0.03 mdyn Å−1 for the bond force constant and2.005 ± 0.005 Å for the strain-free bond length. Modelling the seven Sc(III) porphyrins with the new parameters gives an average Sc-N bond length of 2.182 ± 0.018 Å, indistinguishable from the crystallographic mean of 2.181 ± 0.024 Å.  相似文献   

4.
The [Ru(CN)(6)](3-) ion is synthesized in aqueous solution and isolated as [Ph(4)As](3)[Ru(CN)(6)].2H(2)O (1). Compound 1 crystallizes as orange needles in the monoclinic space group P2(1)/n with cell parameters a = 11.346(2) A, b = 23.107(5) A, c = 25.015(5) A, beta = 99.55(3) degrees, V = 6467.1(22) A(3), Z = 4. The octahedral anion has Ru-C bond lengths in the range 2.023(6)-2.066(6) A. DFT calculations reproduce experimental geometries for [M(CN)(6)](3-) (M = Fe, Ru) equally well and yield significantly higher spin densities on the cyanide ligands in [M(CN)(6)](3-) (M = Ru, Os) than in [Fe(CN)(6)](3-).  相似文献   

5.
Dichlorotetramethyldisiloxane is studied by gas-phase electron diffraction at room temperature. The least-squares values of the bond distances (rg) and bond angles () are: r(C---H)=1.084(5) Å, r(Si---O) = 1.624(2) Å, r(Si---C) = 1.852(2) Å, r(Si---Cl) = 2.067(2) Å, SiOSi = 154.0° (1.5), ClSiO = 110.2° (0.8), ClSiC = 109.6°(0.7), HCSi = 111.7°(1.5), OSiC = 110.0°(0.8), τ1 (zero corresponds to the Si---Cl bond trans to the Si---O---Si linkage) = 78°(6) and τ2 = 141°(19). A two-conformer model cannot be ruled out.  相似文献   

6.
The first observation in the vapour phase of strongly fluorescent exciplexes between complex polyatomic molecules is reported. Systems studied were electronically excited 9-cyano anthracene as electron acceptors with triethyl and tributyl amine and dimethyl aniline as electron donors, at temperatures in the 185–231°C range. Fluorescence spectra, excitation spectra and preliminary decay time data are reported.  相似文献   

7.
The molecular structure and conformation of 1,2-cyclononadiene has been studied by the gas electron diffraction method. The experimental data were interpreted in terms of an unsymmetrical (C1) molecular model and there were no indications of other conformers being present.  相似文献   

8.
The molecular structure and conformation of 1,2,6-cyclononatriene were studied by the gas electron diffraction method. Two different models, differing primarily in the degree of distortion from planarity of the bonds at the isolated CC double bond, give satisfactory agreement with the experimental data.  相似文献   

9.
Crystals of dibromo-η5-cyclopentadienyltris(tetrahydrofuran)ytterbium(III) are monoclinic, P21/n (C2n5, No. 14), with a 15.310(15), b 16.900(17), c 7.968(8) Å, β 96.66(5)° and Z = 4. The ytterbium is pseudo-octahedrally coordinated by a cyclopentadienyl ligand, trans bromines, and mer tetrahydrofuran ligands, and the ytterbium—oxygen distance trans to cyclopentadienyl is longer than the other ytterbium—oxygen bonds.  相似文献   

10.
11.
Summary The synthesis and principle properties of several novel tris[1-(4-X-phenyl)-4,4-dimethylpenta-1, 3-dionato]-iron(III) and manganese(III) complexes, where X=MeO, Me, H, F, Cl and NO2, are described. Magnetic susceptibility measurements in the 4.2–295 K range show a near Curie behaviour and a constant magnetic moment for manganese(III) complexes and for iron complexes, with X=F, Cl or NO2. Iron complexes with ligands having substituents: X=MeO, Me and H, show weak antiferromagnetic interaction (J=ca.–8 cm–1 for the two former compounds) and a decrease in magnetic moment with decreasing temperature. In both manganese(III) and iron(III) complexes the diketonate ligand can be easily replaced by chlorine. Equilibrium constants could be evaluated only for substitution of the third diketonate ligand by chloride in the iron complexes on the basis of spectrophotometric measurements. For manganese chelates, the replacement of the second diketonate by chloride is accompanied by reduction of manganese(III) manganese(II) and free organic radical formation is observed.  相似文献   

12.
13.
The crystal and molecular structure of the adduct (HAlN-i-Pr)6AlH3 has been determined from single-crystal and three dimensional X-ray diffraction data collected by counter methods. The cage-type molecular structure consists of two six-membered rings, (AlN)3, joined together by four adjacent transverse AlN bonds; the loss of two of these bonds allows the complexation of one alane molecule, with five-coordination of the aluminum (trigonal bipyramidal geometry), through two AlN bonds and two AlHAl bridge bonds. The AlN bond lengths range from 1.873 to 1.959 Å; the average AlH bond length is 1.50(1) Å for the four-coordinated aluminum atoms; the average distance of the two apical hydrogens from the five-coordinated aluminum atom is 1.92(5) Å. Colourless prismatic crystals of the compound have the following crystal data: triclinic space group P1; a = 17.13(2); b = 10.78(2); c = 10.20(2) Å; α = 124.3(4), β = 92.0(4), γ = 92.1(5); Z = 2; calculated density 1.157 g/cm3. The structure has been refined by block-matrix, least-squares methods using 4358 independent reflections to a standard unweighted R factor of 4.9%.  相似文献   

14.
(C2F5)2PCl is now accessible through a significantly improved synthesis protocol starting from the technical product (C2F5)3PF2. (C2F5)3PF2 was reduced in the first step with NaBH4 in a solvent‐free reaction at 120 °C. The product, P(C2F5)3, was treated with an excess of an aqueous sodium hydroxide solution to afford the corresponding phosphinite salt Na+(C2F5)2PO? selectively under liberation of pentafluoroethane. Subsequent chlorination with PhPCl4 resulted in the selective formation of (C2F5)2PCl, which was isolated by fractional condensation in an overall yield of 66 %. The gas electron diffraction (GED) pattern for (C2F5)2PCl was recorded and found to be described by a two‐conformer model. A quantum chemical investigation of the potential‐energy surface revealed the possible existence of many low‐energy conformers, each with a number of low‐frequency vibrational modes and therefore large‐amplitude motions. The conformer calculated to be most stable was also found to be most abundant by GED and comprised 61(5) % of the total. The molecular structure parameters determined by GED were in good agreement with those calculated at the MP2/TZVPP level of theory; the only significant difference was a discrepancy of about 3° in the C‐P‐C angle, which, for the lowest‐energy conformer, was refined to 98.2(4)° and was calculated to be 94.9°.  相似文献   

15.
16.
The structure of chloro-bis(1,2-cyclohexanedionediaxwte)triphenylphosphinecobalt(III) [Co(NioxH)2PPh3Cl] was determined by X-ray diffraction analysis. The crystal is monoclinic, a = 17.049(3), b = 15.223(3), c = 11.032(3) å, Β = 87.44(2)?, R(hkl) = 0.068 for 2739 reflections with I ≥2Σ(I). The structure is molecular. In the octahedral complex, the cobalt(III) atom is coordinated by two NioxH residues (av Co-N = 1.876 å), the phosphorus atom (Co-P = 2.307 å), and the Cl- union (Co-Cl = 2.260 å). In the crystal, there are weak intermolecular interactions C-H…Cl and C-H…O.  相似文献   

17.
The electrochemical behaviour of Eu(III), Yb(III,II) and Sm(III,II) has been investigated in NaCl-AlCl3 mixtures, in a temperature range between 150 and 250°C. Principal investigation methods are cyclic voltammetry, pulse polarography and chronoamperometry. The three tervalent lanthanides can be reduced reversibly and solutions of divalent oxidation states are stable. E1/2 potentials measured with respect to an Al electrode in a saturated melt are located respectively at 2.295 V (Eu), 1.630 V (Yb) and 1.080 V (Sm). In acidic chloroaluminates, the three investigated lanthanides are more oxidizing than in other more complexing solvents. If the acidity of the melt is decreased, precipitation of the trichloride (or the dichloride) occurs and the solubility product of the different species is directly related to the cationic size.  相似文献   

18.
Hexafluoro-Dewar-benzene has been studied by the electron-diffraction method. A model with C2v symmetry gives excellent agreement between experimental and theoretical data. The structural parameters with error limits are (cf. Fig. 1): r(C1-C4)= 1.598 ±0.017 Å, r(C1-C2) = 1.505 ±0.005 Å, r(C2-C3) = 1.366 ± 0.015 Å, r(C1-F1) = 1.328±0.015 Å, r(C2-F2) = 1.319±0.007 Å, ∠F1C1C4 = 118.7±0.7°, ∠F2C2C3 = 133.6±0.7°, τ= 121.8±2.0°, and δ = -7.5±2.0°. Molecular orbital calculations by the CNDO/2 method gave τ = 119.8° and δ = ?4.2°.  相似文献   

19.
Summary The activities of the diethylenetriaminemonoacetatocobalt(III) complexes, [Co(en)(DTMA)]I2, [CoX2(DTMA)] and [CoCO3(DTMA)]·H2O (DTMA=diethylenetriaminemonoacetato or formally 3-amino-3, 6-diazaoctanato; en=ethylenediamine, X=Cl, NO 2 , NCS) were studied onEscherichia coli B growing in a minimal glucose medium in both lag- and log-phases. Activities decrease in the order: [Co(NCS)2(DTMA)]> [Co(NO2)2(DTMA)]>[Co(en)(DTMA)]I2>[CoCl2(DTMA)] >[CoCO3(DTMA)]·H2O. The antagonistic activities of the complexes were also studied.  相似文献   

20.
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