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1.
The molecular structure of 3-methylthiophene
has been determined by gas electron diffraction (GED) combined with microwave (MW) spectroscopic data. Ab initio calculations at the HF/3–21G* level were carried out and used as structural constraints in the data analysis. The torsional vibration of the methyl group was treated as a large-amplitude motion. The structural parameters were determined to be: rg(S---C2) = 1.719(2) Å, rg(C2=C3) = 1.370(3) Å, rg(C3---C6) = 1.497(6) Å, rg(C2---H) = 1.101(5) Å, CSC = 91.6(2)°, SC 2C 3 = 113.3(5)°, SC 5C 4 = 111.3(3)°, C 2C 3C 6 = 123.2(11)° and C 3C 6H = 112(2)°. The values of r(S---C 2) - r(S=C 5) and r(C 2=C 3)- r(C 4 =C 5) were fixed at the 3–21G* value of 0.002 Å. Parenthesized values are the estimated limits of error (3σ) referring to the last significant digit. 相似文献
2.
The XeOSeF 5+ 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 AsF 6− as its counter anion. The X-ray crystal structures of the tellurium analogue and of the Xe(OChF 5) 2 derivatives have also been determined: [XeOChF 5][AsF 6] crystallize in tetragonal systems, P4/ n, a=6.1356(1) Å, c=13.8232(2) Å, V=520.383(14) Å 3, 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) Å 3, Z=2 and R1=0.0730 at −113°C (Se); Xe(OTeF 5) 2 crystallizes in a monoclinic system, P2 1/ c, a=10.289(2) Å, b=9.605(2) Å, c=10.478(2) Å, β=106.599(4)°, V=992.3(3) Å 3, Z=4 and R1=0.0680 at −127°C; Xe(OSeF 5) 2 crystallizes in a triclinic system,
, a=8.3859(6) Å, c=12.0355(13) Å, V=732.98(11) Å 3, Z=3 and R1=0.0504 at −45°C. The energy minimized geometries and vibrational frequencies of the XeOChF 5+ cations and Xe(OChF 5) 2 were calculated using density functional theory, allowing for definitive assignments of their experimental vibrational spectra. 相似文献
3.
The crystal structure of N-(2-hydroxy-5-chlorophenyl) salicylaldimine (C 13H 10NO 2Cl) was determined by X-ray analysis. It crystallizes orthorhombic space group P2 12 12 1 with a=12.967(2) Å, b=14.438(3) Å, c=6.231(3) Å, V=1166.5(6) Å 3, 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
4.
The molecular structure of 3-methylthiophene
has been determined by gas electron diffraction (GED) combined with microwave (MW) spectroscopic data. Ab initio calculations at the HF/3–21G* level were carried out and used as structural constraints in the data analysis. The torsional vibration of the methyl group was treated as a large-amplitude motion. The structural parameters were determined to be: rg(S---C2) = 1.719(2) Å, rg(C2=C3) = 1.370(3) Å, rg(C3---C6) = 1.497(6) Å, rg(C2---H) = 1.101(5) Å, CSC = 91.6(2)°, SC2C3 = 113.3(5)°, SC5C4 = 111.3(3)°, C2C3C6 = 123.2(11)° and C3C6H = 112(2)°. The values of r(S---C2) − r(S---C5) and r(C2=C3) − r(C4=C5) were fixed at the 3–21G* value of 0.002Å. Parenthesized values are the estimated limits of error (3σ) referring to the last significant digit. 相似文献
5.
Microwave spectra of allylsilane and its 13C and deuterium substituted species have been measured and assigned for the skew isomer. The rs structure was determined with the aid of several assumptions. Some of the parameters determined are; r(C=C) = 1.328 ± 0.007 Å, r(C---C) = 1.492 ± 0.008 Å, (CCC) = 126.7 ± 0.8°, (CCSi) = 111.6 ± 0.5° and τ(CCCSi) = 106.8 ± 1.1°. Dipole moments and their components were also determined for the CH 2 = CHCH 2SiH 3 and CH 2=CHCH 2SiD 3 species. Hyperconjugation between the C=C π bond and the C---Si σ bond is discussed. 相似文献
6.
The molecular structure of trichloronitromethane has been studied in the gas phase using electron diffraction data. The molecules are found to undergo low barrier rotation about the CN bond with a planar CNO 2 moiety in agreement with HF/MP2/B3LYP/6-311G(d,p) calculations. The experimental data are consistent with a dynamic model using a potential function for the torsion of V = ( V6/2)(1 − cos 6 τ). The major geometrical parameters ( rg and ) for the eclipsed form, obtained from least squares analysis of the data are as follows: r(NO 3) = r(NO 4) = 1.213(2) Å, r(CN) = 1.592(6) Å, r(CCl) av = 1.749(1) Å, Cl 5CN/Cl 6CN = 109. 6°/106.3°(2), O 3NC/O 4NC = 117. 6°/114.1°(4), τCl 5C 1N 2O 3 = 0.0°, and V6 = 0.20(25) kcal/mol. 相似文献
7.
Two nickel (imidazole) complexes, Ni(im) 6Cl 2·4H 2O (1) and Ni(im) 6(NO 3) 2 (2) (im=imidazole) have been synthesized and characterized by elemental analysis, IR, UV, TG and single crystal X-ray diffraction. 1 crystallizes in the triclinic space group P-1 with a=8.800(6) Å, b=9.081(6) Å, c=10.565(7) Å, =75.058(9)°, β=83.143(8)°, γ=61.722(8)°, V=718.3(8) Å 3, Z=1 and R1 ( wR2)=0.0469 (0.1497). 2 crystallizes in the trigonal space group R-3 with a=12.370(6) Å, b=12.370(6) Å, c=14.782(14) Å, =90.00°, β=90.00°, γ=120.00°, V=1959(2) Å 3, Z=3 and R1 ( wR2)=0.0358 (0.0955). 1 and 2 exhibit different supramolecular network due to their different counter anions and different hydrogen bonding connection. In compound 1, [Ni(im) 6] 2+ cation and counter anions Cl − alternatively array in an ABAB fashion via N–HCl hydrogen bonding. In compound 2, the plane of each NO 32− is almost parallel and each NO 32− connect three different [Ni(im) 6] 2+ cations via N–HO hydrogen bonding. 相似文献
8.
The structure of cyclopentadienyl(duroquinone)cobalt dihydrate, (C 5H 5)Co-[(CH 3) 4C 6O 2]·2H 2O, has been determined by three-dimensional X-ray analysis. The crystal structure consists of discrete cyclopentadienyl(duroquinone)cobalt molecules linked together by a complex network of hydrogen bonds between water molecules and duroquinone oxygen atoms. Each (C 5H 5)Co[(CH 3) 4C 6O 2] molecule consists of a cobalt atom sandwiched between a cyclopentadienyl ring and a duroquinone ring. A detailed comparison of the molecular parameters of this complex with those of closely related complexes is given. Crystallographic evidence that the metal---duroquinone interaction in cyclopentadienyl(duroquinone)cobalt dihydrate is considerably stronger than that in the electronically-equivalent 1,5-cyclooctadiene(duroquinone)nickel complex is given not only by the metal---C(olefin) distances being 0.12 Å (av) shorter in the duroquinone---cobalt complex [ viz., 2.104(8) Å vs. 2.222(7) Å] but also by the much greater C2v-type distortion of the duroquinone ring from the planar D2h configuration in free duroquinone. The compound crystallizes with two formula species in a triclinic unit cell of symmetry P
and reduced cell dimensions á = 8.60 Å, b = 9.00 Å, c = 10.15 Å, = 87° 34′, β = 84° 10′, γ = 73° 44′. Least-squares refinement yielded final unweighted and weighted discrepancy factors of R1 = 10.8% and R2 = 12.0%, respectively, for 2481 independent diffraction maxima collected photographically. 相似文献
9.
Two novel hydrogen maleato (HL) bridged Cu(II) complexes ∞1[Cu(phen)Cl(HL) 2/2] 1 and ∞1[Cu(phen)(NO 3)(HL) 2/2] 2 were obtained from reactions of 1,10-phenanthroline, maleic acid with CuCl 2·2H 2O and Cu(NO 3) 2·3H 2O, respectively, in CH 3OH/H 2O (1:1 v/v) at pH=2.0 and the crystal structures were determined by single crystal X-ray diffraction methods. Both complexes crystallize isostructurally in the monoclinic space group P2 1/ n with cell dimensions: 1 a=8.639(2) Å, b=15.614(3) Å, c=11.326(2) Å, β=94.67(3)°, Z=4, Dcalc=1.720 g/cm 3 and 2 a=8.544(1) Å, b=15.517(2) Å, c=12.160(1) Å, β=90.84(8)°, Z=4, Dcalc=1.734 g/cm 3. In both complexes, the square pyramidally coordinated Cu atoms are bridged by hydrogen maleato ligands into 1D chains with the coordinating phen ligands parallel on one side. Interdigitation of the chelating phen ligands of two neighbouring chains via π–π stacking interactions forms supramolecular double chains, which are then arranged in the crystal structures according to pseudo 1D close packing patterns. Both complexes exhibit similar paramagnetic behavior obeying Curie–Weiss laws χ m( T−θ)=0.414 cm 3 mol −1 K with the Weiss constants θ=−1.45, −1.0 K for 1 and 2, respectively. 相似文献
10.
The infrared spectra (3500 to 40 cm −1) of gaseous and solid and the Raman spectra (3500 to 30 cm −1) of liquid and solid 1-fluorosilacyclobutane, c-C 3H 6SiFH, have been obtained. Both the axial and equatorial conformers with respect to the fluorine atom have been identified in the fluid phases. Variable temperature (−105 to −150 °C) studies of the infrared spectra of the sample dissolved in liquid krypton have been carried out. From these data, the enthalpy difference has been determined to be 282 ± 27 cm −1 (3.37 ± 0.32 kJ/mol), with the equatorial conformer the more stable form and the only conformer remaining in the annealed solid. At ambient temperature there is approximately 21 ± 2% of the axial conformer present in the vapor phase. From isolated Si–H stretching frequencies the Si–H ( r0) distances are calculated to be 1.484 and 1.485 Å for the equatorial and axial conformers, respectively. Structural parameters have been predicted from MP2/6-311 + G(d,p) ab initio calculations and the adjusted r0 parameters for both conformers were obtained from a combination of the ab initio predicted values and the six previously reported microwave rotational constants. Along with the Si–H bond distance, the Si–C, and C–C distances of 1.865(5), and 1.571(5) Å, respectively, for the equatorial conformer are significantly different from the values for these parameters previously reported from an election diffraction study. Both the SiC and CC distances and the SiF distance are longer by 0.002 and 0.004 Å, respectively, for the axial conformer. Structural parameters have also been obtained for silacyclobutane, c-C 3H 6SiH 2 and ethylsilylfluoride, CH 3CH 2SiH 2F, from combined ab initio predicted values and previously reported rotational constants. Several of these newly determined parameters are significantly different from those previously reported for both molecules. Complete equilibrium geometries, conformational stabilities, harmonic force fields, infrared intensities, Raman activities, and depolarization ratios have been determined for both rotamers by ab initio calculations employing the 6-31G(d) basis set at the level of Moller–Plesset (MP) to second order. A complete vibrational assignment supported by normal coordinate calculations is proposed for the equatorial conformer, and several of the fundamentals of the axial conformer have also been identified. The results are discussed and compared to corresponding quantities for some similar molecules. 相似文献
11.
Crystals of the adduct, BrF 3·AuF 3, are monoclinic, with: a=5.356(4) Å, b=5.766(4) Å, c=8.649(3) Å, β=101.39(4)°, V=261.8(5) Å 3, z=2, Dc=4.96 g/cm 3. An ordered structure in P21 was found, but is of low precision ( R1=0.082) because of crystal deformation. The structure has planar BrF 4 units sharing F ligands cis with planar AuF 4 groups, each AuF 4 being similarly linked to two BrF 4. This generates a ribbon, creased at the bridging F along y, the gold on one side of the crease, the bromine on the other. Such ribbons are stacked parallel along y, with nearest neighbors related by twofold screw axes. This sandwiches each AuF 4 strip of a ribbon symmetrically between like strips. These contacts between the Au-strips bring up, to each Au-atom, two “non-bridging Au–F ligands” of each of the two neighboring strips, to give eight coordination in F. The bromine side of the creased ribbon is unsymmetrically sandwiched between a screw-axis related relative, and the edge of a Au-containing strip oriented almost perpendicular to it. This brings two non-bridging F of the nearest-strip BrF 4 and two non-bridging F of the AuF 4 strip into the secondary cordination sphere of the Br atom. Raman spectra of the BrF 3·AuF 3, molecular BrF 3, and polymeric AuF 3 suggest that the Br–F and Au–F stretching vibrations of BrF 3·AuF 3 are shifted slightly from those of the parent BrF 3 and AuF 3, and indicate some BrF 2+AuF 4− character. 相似文献
12.
The geometric structure of (CH 3) 3Si---NSO in the vapour phase has been determined by gas electron diffraction. The molecule possesses a planar Si---N=S=O skeleton with syn conformation. The Si(CH 3) 3 group staggers the N=S double bond. The following skeletal parameters ( ra distances and angles with 3σ errors limits) were obtained: Si---N 1.750(6)Å, N=S 1.508(5)Å, S=O 1.444(4)Å, Si---N=S 133.9(9)°, N=S=O 122.5(10)°. Ab initio calculations (HF/3−21G*) were performed for H 3Si---NSO and confirm the planar syn structure for sulfinyl silanamines. 相似文献
13.
Gaseous 3-chloro-1-butene has been studied experimentally by electron diffraction (ED) at 20 and 180°C, and at these temperatures, 76(10)% and 62(10)%, respectively, of the most stable conformer i.e. the one having a hydrogen atom eclipsing the double bond, were found. The conformer with the chlorine atom eclipsing the C=C bond was also present. However, from the experimental data it was not possible to establish conclusive evidence for the conformer with an eclipsed CH 3 group. Molecular mechanics (MM) calculations and ab initio calculations using a 4-21 basis set were carried out with complete geometry optimization, and calculated parameters from each of the methods were used in combination with the ED data. Such calculations indicated the existence of all three conformers mentioned above. Least-squares analysis including constraints from the ab initio calculation gave as a result the following molecular structure ( ra distances and ??? angles) for the predominant conformer: r(C=C) = 1.337(6) Å, r(=C---C) = 1.503(4) Å, r(C---CH 3) = 1.522 Å, R(C---Cl) = 1.813(4) Å, < r(C---H)> = 1.089(18) Å, ???C=C---C = 122.9(2.1)°, ???C---C---C = 112.6(2.2)°, ???=C---C---Cl = 109.9(0.2)°, ???Cl---C---CH 3 = 109.3°. ?? C=C---H> = 121.9° and ?? C---C---H> = 110.0(1.3)°. The torsional angles were then τ(C=C---C---Cl> = −119.4° and τ(C=C---C---CH 3) = 120.3(2.1)°. Error limits are 2σ (σ includes estimates of systematic errors and correlations), parameters without quoted uncertainties are dependent or were constrained relative to another parameter. Combining the ED data with MM results yielded parameters consistent with those given above. 相似文献
14.
New ester salts [R 3NH] +[F 5SC(SO 2F)C(O)OR′] − where RH, CH 3CH 2 and R′CH 3,(CH 3) 2CH have been prepared from corresponding esters and amines. The sodiumsalt Na[F 5SC(SO 2F)C(O)OCH(CH 3) 2] was used to prepare the following -substitutedderivatives: SF 5CX(SO 2F)C(O)OCH(CH 3) 2, XBr, Cl. The crystal structure of[(C 2H 5) 3NH] +[F 5SC(SO 2F)C(O)OCH 3] − was determined and is monoclinic: P2 1/ n; a=8.758(2) Å, b=9.645(2) Å and c=19.167(4) Å; β=97.92(3)°; V=1603.6 Å 3; Z=4. 相似文献
15.
The thermal decomposition of CaOsO 3 by differential thermal analyses, thermogravimetry and X-ray powder diffraction has been studied. In nitrogen CaOsO 3 decomposes at 880 ± 10°C into CaO, osmium metal and oxygen due to the reaction CaOsO 3 → CaO + Os + O 2. In static air the decomposition occurs in three stages: 2CaOsO 3 + 1/2O 2 → Ca 2Os 2O 7 (in region 775–808°C), Ca 2Os 2O 7 → Ca 2Os 2O 6,5 + 1/4O 2 (at a temperature interval of 850–1000°C) and in the third stage Ca 2Os 2O 6,5 → 2CaO + OsO 4 ÷ 1/4 O 2 (at 1005 ± 5°C). The first intermediate Ca 2Os 2O 7 is isostructural with orthorhombic Ca 2Nb 2O 7 and its cell parameters are: a0 = 3.745 Å, b0 = 25.1 Å, c0 = 5.492 Å, Z = 4, space group Cmcm or Cmc2. Ca 2Os 2O 7 exhibits metallic conductivity and its electrical resistivity is 4.6 × 10 −2 ohm-cm at 296K. 相似文献
16.
A novel three-dimensional (3D) mixed-valence iron coordination polymer [Fe 2IIIFe IIO 2(IN) 2(ox)] (IN=isonicotinate, OX=oxalate) (1) has been hydrothermally synthesized by using two different anionic ligands and characterized by elemental analysis, IR spectrum, electron spin resonance (ESR), X-ray photoelectron spectrum (XPS), thermogravimetric analysis (TGA) and single crystal X-ray diffraction. Compound 1 crystallizes in the monoclinic, space group P2(1)/ c with a=5.8774(7) Å, b=18.528(2) Å, c=7.7117(9) Å,
V=817.69(17) Å 3, Z=2, and R1=0.0321 ( wR2=0.0777). The Fe(II) and Fe(III) centers in 1 both exhibit a distorted octahedral coordination geometry and are bridged by the IN and oxalate groups into a covalently bonded 3D metal–organic network. TGA showed that the 3D network possesses a good stability up to 291 °C. 相似文献
17.
Microdifferential thermal analysis (μ-DTA), X-ray diffraction (XRD) and infrared (IR) spectroscopy were used for the first time to investigate the liquidus and solidus relations in the KPO 3–Y(PO 3) 3 system. The only compound observed within the system was KY(PO 3) 4 melting incongruently at 1033 K. An eutectic appears at 13.5 mol% Y(PO 3) 3 at 935 K, the peritectic occurs at 1033 K and the phase transition for potassium polyphosphate KPO 3 was observed at 725 K. Three monoclinic allotropic phases of the single crystals were obtained. KY(PO 3) 4 polyphosphate has the P2 1 space group with lattice parameters: a=7.183(4) Å, b=8.351(6) Å, c=7.983(3) Å, β=91.75(3)° and Z=2 is isostructural with KNd(PO 3) 4. The second allotropic form of KY(PO 3) 4 belongs to the P2 1/ n space group with lattice parameters: a=10.835(3) Å, b=9.003(2) Å, c=10.314(1) Å, β=106.09(7)° and Z=4 and is isostructural with TlNd(PO 3) 4. The IR absorption spectra of the two forms show a chain polyphosphates structure. The last modification of KYP 4O 12 crystallizes in the C2/ c space group with lattice parameters: a=7.825(3) Å, b=12.537(4) Å, c=10.584(2) Å, β=110.22(7)° and Z=4 is isostructural with RbNdP 4O 12 and contains cyclic anions. The methods of chemical preparations, the determination of crystallographic data and IR spectra for these compounds are reported. 相似文献
18.
Organolanthanide chloride complexes [(CH 3OCH 2CH 2C 5H 4) 2Ln(μ-Cl)] 2 (Ln = La, Pr, Ho and Y) react with excess NaH in THF at 45°C to give the dimeric hydride complexes [(CH 3OCH 2CH 2C 5H 4) 2Ln(μ-H)] 2, which have been characterized by IR, 1H NMR, MS and XPS spectroscopy, elemental analyses and X-ray crystallography. [(CH 3OCH 2CH 2C 5H 4) 2Y(μ-H)] 2 crystallizes from THF/n-hexane at −30°C, in the triclinic space group P1 with a = 8.795(2) Å, b = 11.040(1) Å, c = 16.602(2) Å, = 93.73(1)°, β = 91.82(1)°, γ = 94.21(1)°, Dc = 1.393 gcm −3 for Z = 2 dimers. However, crystals of [(CH 3OCH 2CH 2C 5H 4) 2Ho(μ-OH)] 2 were obtained by recrystallization of holmium hydride in THF/n-hexane at −30°C, in the orthorhombic space group Pbca with a = 11.217(2) Å, b = 15.865(7) Å, c = 17.608(4) Å, Dc = 1.816 gcm −3 for Z = 4 dimers. In the complexes of yttrium and holmium, each Ln atom of the dimers is coordinated by two substituted cyclopentadienyl ligands, one oxygen atom and two hydrogen atoms (for the Y atom) or two hydroxyl groups (for the Ho atom) to form a distorted trigonal bipyramid if the C(η 5)-bonded cyclopentadienyl is regarded as occupying a single polyhedral vertex. 相似文献
19.
The bimetallic [Pt(NH 3) 4] 2[W(CN) 8][NO 3]·2H 2O is characterised by single-crystal X-ray diffraction [S.G. P2 1/ m(11), a=8.0418(7), b=19.122(2), c=9.0812(6) Å, Z=2]. All platinum centres have the square-plane D4h geometry with average dimensions Pt(1)–N 2.042(2) and Pt(2)–N 2.037(10) Å. The octacyanotungstate anion has the square-antiprismatic D4d configuration with average dimensions W(1)–C 2.164(13), C–N 1.140(12), W(1)–N 3.303(5) Å. The structure exhibits two different mutual orientations of Pt versus W units resulting in Pt(2)–W(1), W(1) * separations of 4.77(2), 4.55(2) * and Pt(1)–W(1) of 6.331(8) Å. A centrosymmetric structure reveals groups of two distinct columns: the first is formed by intercalated NO 3− between parallel [Pt(1)(NH 3) 4] 2+ planes and the second consists of [W(CN) 8] 3− interlayered by, parallel to square faces of W-antiprisms, [Pt(2)(NH 3) 4] 2+. The structure is stabilised through a three-dimensional hydrogen bond network via nitrogen atoms of cyanide ligands, hydrogen atoms of NH 3 ligands, water molecules and oxygen atoms of NO 3− counteranions. The vibrational pattern and the range of ν(CN) frequencies attributable to the electronic environment of W(V) and W(IV) are consistent with the ground state Pt(II)↔W(V) charge transfer. 相似文献
20.
A gas phase electron diffraction study of 3-bromo-2-methyl-1-propene shows that there is predominantly a gauche conformer present. Data recorded at 20 and 180°C show 4(8) and 5(4)% respectively of a second confomer with a planar heavy atom skeleton. The gauche structural results in terms of ra distances and angles at 20°C were found to be: r(C---C) = 1.331(9) Å, r(C---CH 2Br) = 1.484(6) Å, r(C---CH 3) — r(C---CH 2Br) = 0.017 Å, (assumed), r(C---Br) = 1.965(6) Å, C=C---CH 2Br = 121.5(0.7)°, C=C---CH 2Br — C=C---CH 3 = 0.7° (constraint from molecular mechanics calculation), C---C---Br = 112.2(0.5)°, torsional ANGLE = 112.5(2.2)°. Uncertainties are given as 2σ, where σ includes uncertainties due to correlation among observations, electron wavelength and other parameters used in the data reduction. The results obtained from the 180°C data agree very well with those given above. The molecular mechanics calculations yield information consistent with the experimental results. 相似文献
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