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1.
The pentaamminecobalt(III) complex with the 3-cyano-2,4-pentanedionate anion coordinated through the nitrile nitrogen has been characterized by X-ray crystallography. The crystals of [(NH3)5CoNCacac](Cl)(ClO4)·2H2O are triclinic, space group P , a = 10.245(2) Å, b = 14.071(4) Å, c = 6.971(2) Å, = 90.03(3)°, β = 109.86(2)°, γ = 108.91(2)°, V= 887.1 Å3, Z = 2, Dc = 1.64 g cm−3, F(000) = 456, Mo-K radiation, λ = 0.71069 Å, μ(Mo-K) = 12.7 cm−1. The structure was determined by the heavy-atom method, and refined by block-diagonal least-squares calculations, R = 0.0537, Rw = 0.0607, for 2499 observed reflections. Principal dimensions are: Co---N(NH3) trans to NCacac 1.940(5), other Co---N(NH3) 1.967(2), Co---N(NCacac) 1.911(5) Å. The pendant acac moiety is best described in terms of a delocalized bond network with, for example, C---C distances in the range 1.44–1.52(1) Å. Several reactions involving this free acac group are also described including the preparation and characterization of the dimeric species pentaamminecobalt(III) - μ - (3 - cyano - 2,4 - pentanedionato) - bis(propylenediamine) cobalt(III) perchlorate.  相似文献   

2.
The crystal structures of pharmaceutical product mesalazine (marketed also under different proprietary names as Salofalk, Asacol, Asacolitin, and Claversal) and its hydrochloride are reported. In the crystal mesalazine is in zwitterion form as 5-ammoniosalicylate (1) whereas mesalazine hydrochloride crystallizes in an ionized form as 5-ammoniosalicylium chloride (2). Compound 1 (C7H7O3N) crystallizes in the monoclinic space group P21/n with a = 3.769(1) Å, b = 7.353(2) Å, c = 23.475(5) Å, β = 94.38(2)°, V = 648.7(8) Å3, Z = 4, Dc = 1.568 g cm−3 and μ(MoK) = 1.2 cm−1. Compound 2 (C7H8O3NCl) crystallizes in the triclinic space group P with a = 4.4839(2) Å, b = 5.7936(2) Å, c = 15.6819(5) Å, = 81.329(3)°, β = 88.026(3)°, γ = 79.317(4)°, V = 395.74(3) Å3, Z = 2, Dc = 1.591 g cm−3 and μ(CuK) = 40.8 cm−1. The crystal structures were solved by direct methods and refined to R = 0.041 for 1 and 0.028 for 2, using 607 and 1374 observed reflections, respectively. The configuration of both molecules, with the ortho hydroxyl to a carboxyl group, favours the intramolecular hydrogen bonds. Very complex systems of intermolecular hydrogen bonds were observed in both crystal packings. They are discussed in terms of graph-set notation. The mesalazine crystal structure is characterized by two-dimensional network of hydrogen bonds in the ab plane. The crystal structure pattern of mesalazine hydrochloride is a three-dimensional network significantly supported by N+---HCl interactions.  相似文献   

3.
The structure of the complex [Ni(hmt)(NCS)2(H2O)2]n, assembled by hexamethylenetetramine (hmt) and octahedral Ni(II), is reported. Crystal data: Fw 351.07, a=9.885(10) Å, b=12.06(1) Å, c=12.505(8) Å, β=114.41(4)°, V=1357(1) Å3, Z=4, space group=C2/c, T=173 K, λ(MoK)=0.71070 Å, ρcalc=1.718 gcm−1, μ=17.44 cm−1, R=0.099, Rw=0.145. The tetrahedral assembling template effect of the hmt molecule is completed by two coordination bonds and two hydrogen interactions. The UV–vis absorption spectrum of this complex [Ni(hmt)(NCS)2(H2O)2]n with a two-dimensional network is determined in the range of 5000–35000 cm−1 at room temperature. The observed spectrum is discussed and explained perfectly by the scaling radial theory proposed by us. The two-dimensional structure has no apparent effects on the d–d transitions of the central Ni(II) ion. The IR spectrum and the GT curve of the complex were also measured and clearly reflect its structural properties.  相似文献   

4.
Reaction of the optically active primary amine (S)-(—)--methylbenzylamine with trimethylaluminium in heptane affords the crystalline organoaluminium dimer (S)-(—)-(S)-(—)-[(C6H5)CH(CH3)NHA1(CH3)2]2. Isolated as large, colourless, extremely air-sensitive prismatic crystals, the title compound crystallizes in the orthorhombic space group P212121 with unit cell parameters a = 8.406(3), b = 15.505(4), c = 17.547(5) Å, V = 2287 Å3 and p = 1.03 g cm−3 for Z = 4. Least-squares refinement based on 1477 observed reflections converged at R = 0.056, Rw = 0.058. Methane was eliminated during the course of the reaction due to cleavage of A1---C and N---H bonds resulting in an asymmetric A12N2 fragment at the core of the organoaluminium dimer. The mean A1---C bond distance in the dimethylaluminium units is 1.930(8), while the mean A1---N bond distance is 1.950(5) Å. Specific rotation ([]D25 in CH2C12)of the dimer is determined to be - 20.6°.  相似文献   

5.
The convergence of ab initio calculations of the beryllium dimer potential is examined with several basis sets orders of perturbation theory. When the atomic pair natural orbital basis set calculations are extrapolated to the complete basis set and full CI limits, the calculated parameters: Re=2.447 Å, De=827 cm−1, ν01=212.7 cm−1, ν12=167.2 cm−1, ν23=121.5 cm−1 and ν34=77.7 cm−1 are in good agreement with the experimental parameters: Re=2.45 Å, De=839±10 cm−1, ν01=223.2 cm−1, ν12=169.7 cm−1, ν23=122.5 cm−1, and ν34=79 cm−1.  相似文献   

6.
To evaluate the contribution of local pulsed heating of light-absorbing microregions to biochemical activity, irradiation of Escherichia coli was carried out using femtosecond laser pulses (λ = 620 nm, τp=3 × 10−13 s, fp = 0.5 Hz, Ep = 1.1 × 10−3J cm−2, Iav = 5.5 × 10−4 W cm−2, Ip = 109 W cm−2) and continuous wave (CW) laser radiation (λ = 632.8 nm, I = 1.3 W cm−2). The irradiation dose required to produce a similar biological effect (a 160%–190% increase in the clonogenic activity of the irradiated cells compared with the non-irradiated controls) is a factor of about 103 lower for pulsed radiation than for CW radiation (3.3 × 10−1 and 7.8 × 102 J cm−2 respectively). The minimum size of the microregions transiently heated on irradiation with femtosecond laser pulses is estimated to be about 10 Å, which corresponds to the size of the chromophores of hypothetical primary photoacceptors—respiratory chain components.  相似文献   

7.
Polarized absorption spectra of Ba(MnO4)2·3H2O/Ba(ClO4)2·3H2O mixed single crystals are reported at 4.2°K. Previous 1T21A1 assignments for the 5200 Å and 3000 Å absorption bands of MnO4 are substantiated; further support is provided for the 1T11A1 assignment of the 3600 Å absorption band of MnO4. The site-splitting of the 5200 Å 1T2 state is E(1E)−E(1A) ≈ −150 cm−1; that of the 3000 Å 1T2 state is E(1E)−E(1A) ≈ 300 cm−1. A significant e vibronic intensity component is observed in the 5200 Å 1T2 state.  相似文献   

8.
Crystals of bis(2,6-dimethylpyridine-N-oxide) sulphate are monoclinic, space group P21/c, a = 14.098(2) Å, b = 7.855(1) Å, c = 15.203(3) Å, β = 104.84(1)°. The crystal structure has been refined to R = 0.0373 (2052 reflections). The disordered SO2−4 anion accepts hydrogen bonds from two protonated 2,6-dimethylpyridine-N-oxides and two alternative conformations of the SO2−4 group are distinguished. The occupancy factor of the predominant orientation is 0.63 and the O...O distances are 2.445(2) and 2.453(4) Å; in the second form (fraction, 0.37), these distances are 2.445(2) and 2.544(9) Å.

The PM3 and AM1 methods predict three minima for the title complex, whereas the SAM1 and BLYP/6-31G methods predict only one. All methods predict that molecular complex 3 is the most stable. The SAM1 geometry is very close to that of BLYP/6-31G.

The Fourier transform IR (FTIR) spectrum shows a very intense and broad (continuum) absorption within the 1600-400 cm−1 region, typical of short hydrogen bonds. There is no absorption in the 3000-2000 cm−1 region expected for the longer hydrogen bond (2.544(9) Å) in the less populated orientation. Isotope and solvent effects are discussed.  相似文献   


9.
The crystal structures of propionaldehyde complex (RS,SR)-(η5-C5H5)Re(NO)(PPh3)(η2-O=CHCH2CH3)]+ PF6 (1b+ PF6s−; monoclinic, P21/c (No. 14), a = 10.166 (1) Å, b = 18.316(1) Å, c = 14.872(2) Å, β = 100.51(1)°, Z = 4) and butyraldehyde complex (RS,SR)-[(η5-C5H5)Re(NO)(PPh3)(η2-O=CHCH2CH2CH3)]+ PF6 (1c+PF6; monoclinic, P21/a (No. 14), a = 14.851(1) Å, b = 18.623(3) Å, c = 10.026(2) Å, β = 102.95(1)°, Z = 4) have been determined at 22°C and −125°C, respectively. These exhibit C O bond lengths (1.35(1), 1.338(5) Å) that are intermediate between those of propionaldehyde (1.209(4) Å) and 1-propanol (1.41 Å). Other geometric features are analyzed. Reaction of [(η5-C5H5)Re(NO)(PPh3)(ClCH2Cl)]+ BF4 and pivalaldehyde gives [(η5-C5H5)Re(NO)(PPh3)(η2-O=CHC(CH3)3)]+BF4 (81%), the spectroscopic properties of which establish a π C O binding mode.  相似文献   

10.
Synthesis, structure, spectroscopy and thermal properties of complex [Co(NCS)2(hmt)2(H2O)2][Co(NCS)2(H2O)4] (H2O) (I), assembled by hexamethylenetetramine and octahedral Co(II) metal ions, are reported. Crystal data for I: Fw 387.34, a=9.020(8), b=12.887(9), c=7.95(1) Å, =96.73(4), β=115.36(5), γ=94.16(4)°, V=820(1) Å3, Z=2, space group=P−1, T=173 K, λ(Mo-K)=0.71070 Å, ρcalc=1.718567 g cm−3, μ=17.44 cm−1, R=0.088, Rw=0.148. An interesting two-dimensional network is assembled via hydrogen bonds through coordinated and free water molecules. The d–d transition energy levels of Co(II) ion are determined by UV–vis spectroscopy and calculated by ligand field theory. The calculated results agree well with experiment ones.  相似文献   

11.
The XeOSeF5+ cation has been synthesized for the first time and characterized in solution by 19F, 77Se and 129Xe NMR spectroscopy and in the solid state by X-ray crystallography and Raman spectroscopy with AsF6 as its counter anion. The X-ray crystal structures of the tellurium analogue and of the Xe(OChF5)2 derivatives have also been determined: [XeOChF5][AsF6] crystallize in tetragonal systems, P4/n, a=6.1356(1) Å, c=13.8232(2) Å, V=520.383(14) Å3, Z=2 and R1=0.0453 at −60°C (Te) and a=6.1195(7) Å, c=13.0315(2) Å, V=488.01(8) Å3, Z=2 and R1=0.0730 at −113°C (Se); Xe(OTeF5)2 crystallizes in a monoclinic system, P21/c, a=10.289(2) Å, b=9.605(2) Å, c=10.478(2) Å, β=106.599(4)°, V=992.3(3) Å3, Z=4 and R1=0.0680 at −127°C; Xe(OSeF5)2 crystallizes in a triclinic system, , a=8.3859(6) Å, c=12.0355(13) Å, V=732.98(11) Å3, Z=3 and R1=0.0504 at −45°C. The energy minimized geometries and vibrational frequencies of the XeOChF5+ cations and Xe(OChF5)2 were calculated using density functional theory, allowing for definitive assignments of their experimental vibrational spectra.  相似文献   

12.
The mid-infrared spectrum of the ionic complex He---NH4+ has been recorded in the vicinity of the triply degenerate ν3 (t2) vibration of the free ammonium ion. Apart from a small blue shift (≈ 0.7 cm−1), the spectrum of the complex closely resembles that of the monomer. Ab initio calculations predict a vertex-bound minimum structure with an intermolecular well depth De ≈ 150 cm−1, a center-of-mass separation of Re ≈ 3.17 Å and barriers for internal rotation less than 30 cm−1.  相似文献   

13.
The structures of the title compounds have been established by X-ray crystallography from diffractometer data. Crystals of the first (I), C4H8N4S, are monoclinic, space group P21/c, with a = 8.166(2), b = 10.481(1), c = 8.585(1) Å, β = 109.33(2)°, Z = 4, Dc = 1.381 g cm−3. Crystals of the second (II), C9H10N4S, are monoclinic, space group P21/c, with a = 11.850(4), b = 7.898(1), c = 23.981 (6) Å, β = 117.23(2)°, Z = 8, Dc = 1.373 g cm−3. Crystals of the third (III), C11H14N4S1 are also monoclinic, space group P21/c with a = 12.829(3), b = 8.348(1), c = 11.088(4) Å, β = 94.40(4)°, Z = 4, Dc = 1.314 g cm−3. The structures, determined by direct methods (I, III) and Patterson synthesis (II) were refined to R = 0.039 for 1070 reflections of I, R = 0.040 for 2792 reflections of II and R = 0.041 for 1900 reflections of III. The characteristic features of the planar five-membered rings are studied in comparison with the analogous 1,2,3-triazoles and imidazoles. It is shown that these planar rings exhibit only two patterns of the endocyclic bond angles induced dominantly by the number and relative position of the N-lone pairs. A similar effect of the double bonds (attached to C atoms) is also discussed.  相似文献   

14.
In toluene as medium, tetra(cyclopentadienyl)niobium(IV), NbCp4, has been prepared in satisfactory yields from the reaction of NaCp with: (a) Nb2C110, (b) NbCl4(THF)2, or (c) NbCp2Cl2. Tetracyclopentadienylniobium(IV) has been characterized by X-ray diffraction. Crystal data: C20H20Nb, M=353.29 g mol−1, hexagonal, space group P65 (no. 170), a=b=9.396(2), c=31.23(3) Å, V=2388(2) Å3, Z=6, dcalc=1.48 g cm−3, λ(Cu–K)=1.54184 Å, T=291 K, μ=62.04 cm−1, F(000)=1686. Two of the four cyclopentadienyl ligands are bonded to niobium in a pentahapto fashion, the other two being monohapto. NbCp4 undergoes cyclopentadiene elimination in the presence of species containing active protons such as Ph3SiOH or strong acids, the products being tris- or biscyclopentadienyl compounds depending on the molar ratio of the reagents.  相似文献   

15.
X-ray studies indicate that indanone-1 crystals belong to a monoclinic system, space group P21/c (C52h), with the following parameters: a = 7.90±0.01 Å; b = 12.38±0.01 Å; c = 7.39±0.01 Å; β = 99°±30' and Z = 4. A vibrational assignment of fundamental bands observed in the polarized infrared spectrum between 4000 cm−1 and 250 cm−1 is proposed. The band fine structure analysis at 77 °K shows a doublet structure, which agrees with X-ray data.  相似文献   

16.
The methylene-bridged, mixed-chalogen compounds Fe2(CO)6(μ-SeCH2Te) (1) and Fe2(CO)6(μ-SCH2Te) (3) have been synthesised from the room temperature reaction of diazomethane with Fe2(CO)6(μ-SeTe) and Fe2(CO)6(μ-STe), respectively. Compounds 1 and 3 have been characterised by IR, 1H, 13C, 77Se and 125Te NMR spectroscopy. The structure of 1 has been elucidated by X-ray crystallography. The crystalsare monoclinic,space group P21/n, A = 6.695(2), B = 13.993(5), C = 14.007(4)Å, β = 103.03(2)°, V = 1278(7) Å3, Z = 4, Dc = 2.599 g cm−3 and R = 0.030 (Rw = 0.047).  相似文献   

17.
A series of eight materials of stoichiometry [Pt(L-L)2X2][Pt(L-L)2]Y4 (X is Cl, Br; L-L is 1,2-diaminoethane (en) or 1,2-diaminocyclohexane (chxn); Y is ClO4, X) were synthesized. Crystal structures were determined for the compounds [Pt(chxn)2Cl2][Pt(chxn)2](ClO4)4 1, [Pt(chxn)2Br2][Pt(chxn)2](ClO4)42, and [Pt(chxn)2Br2][Pt(chxn)2]Br4 4. All three of these compounds crystallize in the orthorhombic space group I222. Compound 1 has a = 5.711(1) Å, b = 7.804(1) Å, c = 24.101(7) Å, Z = 1, dx = 2.033 g cm−3. Compound 2 has a = 5.781(1) Å, b = 7.720(1) Å, c = 24.036(5) Å, Z = 1, dx = 2.174 g cm−3. Compound 4 has a = 5.379(1) Å, b = 7.028(1) Å, c = 23.884(4) Å, Z = 1, dx = 2.440 g cm−3. These solids contain pseudo one-dimensional chains with a charge-density-wave (CDW) ground state structure: X-Pt(IV)-X···Pt(II)···X. Single crystal resonance Raman experiments were performed on all compounds to measure the symmetric X---Pt---X stretching frequency v1 and the band edge. It is shown that the optical and electronic properties and, therefore, the CDW strength of these one-dimensional materials may be systematically varied over a wide range by employing different combinations of L-L and Y; templates composed of hydrogen bonded networks of L-L and Y were found to control the metal-metal separation, thereby controlling the X---Pt(IV)---X…Pt(II)…X chain geometry. Relationships between the CDW strength, measured as the ratio of the short M(IV)---X distance to the long M(II)---X distance, the band gap energy v1 and the Pt---Pt separation are developed. The reaction coordinate is found to be dominated by changes in the M---M and Pt(II)---X separations over most of the range studied, with contributions from changes in the PtIV---X bonds becoming important only at the smallest M---M separations. Direct evidence demonstrating that MX systems are true Peierls distorted systems is also presented. These results are consistent with modeling based on Peierls-Hubbard hamiltonians. This work explains the unusual pressure and temperature dependences that have been observed for the structures and optical properties of this class of materials and also provides a wealth of information to benchmark many-body theoretical calculations modeling electron-electron and electron-phonon interactions in one-dimensional materials.  相似文献   

18.
The crystal structure of N-(2-hydroxy-5-chlorophenyl) salicylaldimine (C13H10NO2Cl) was determined by X-ray analysis. It crystallizes orthorhombic space group P212121 with a=12.967(2) Å, b=14.438(3) Å, c=6.231(3) Å, V=1166.5(6) Å3, Z=4, Dc=1.41 g cm−3 and μ(MoK)=0.315 mm−1. The title compound is thermochromic and the molecule is nearly planar. Both tautomeric forms (keto and enol forms in 68(3) and 32(3)%, respectively) are present in the solid state. The molecules contain strong intramolecular hydrogen bonds, N1–H1O1/O2 (2.515(1) and 2.581(2) Å) for the keto form and O1–H01N1 for the enol one. There is also strong intermolecular O2–HO1 hydrogen bonding (2.599(2) Å) between neighbouring molecules. Minimum energy conformations AM1 were calculated as a function of the three torsion angles, θ1(N1–C7–C6–C5), θ2(C8–N1–C7–C6) and θ3(C9–C8–N1–C7), varied every 10°. Although the molecule is nearly planar, the AM1 optimized geometry of the title compound is not planar. The non-planar conformation of the title compound corresponding to the optimized X-ray structure is the most stable conformation in all calculations.  相似文献   

19.
N-(2-hydroxyphenyl)-4-amino-3-penten-2-on (C11H13NO2) has been studied by X-ray analysis. It crystallizes the orthorhombic space group P212121 with a=8.834(1), b=10.508(2), c=11.212(2) Å, V=1040.8(3) Å3, Z=4, Dc=1.22 g cm−3 and μ(MoK)=0.084 mm−1. The structure was solved by direct methods and refined to R=0.038 for 1373 reflections (I>2σ(I)). The title compound is photochromic and the molecule is not planar. Intramolecular hydrogen bonds occur between the pairs of atoms N(1) and O(1) [2.631(2) Å], and N(1) and O(2) [2.641(2) Å], the H atom essentially being bonded to the N atom. There is also a strong intermolecular O–HO hydrogen bonding [2.647(2) Å] between neighbouring molecules. Tautomeric properties and conformations of the title compound were investigated by semi-empirical quantum mechanical AM1 calculations and the results are compared with the X-ray results.  相似文献   

20.
Nest-shaped cluster [MoOICu3S3(2,2′-bipy)2] (1) was synthesized by the treatment of (NH4)2MoS4, CuI, (n-Bu)4NI, and 2,2′-bipyridine (2,2′-bipy) through a solid-state reaction. It crystallizes in monoclinic space group P21/n, a=9.591(2) Å, b=14.820(3) Å, c=17.951(4) Å, β=91.98(2)°, V=2549.9(10) Å3, and Z=4. The nest-shaped cluster was obtained for the first time with a neutral skeleton containing 2,2′-bipy ligand. The non-linear optical (NLO) property of [MoOICu3S3(2,2′-bipy)2] in DMF solution was measured by using a Z-scan technique with 15 ns and 532 nm laser pulses. The cluster has large third-order NLO absorption and the third-order NLO refraction, its 2 and n2 values were calculated as 6.2×10−10 and −3.8×10−17 m2 W−1 in a 3.7×10−4 M DMF solution.  相似文献   

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