首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The intramolecular dynamic behavior of the tetrahedrane-type cluster [Fe2(CO)6(μ-SNH)] 1 was studied by 13C NMR spectroscopy. The 57Fe chemical shift of 1 and the coupling constants 1 J(57Fe,13C) were measured. These NMR parameters, and also 1 J(57Fe,15N), were found to be in good agreement with data calculated by using density functional theory (DFT) methods (B3LYP), based on the geometry calculated at the 6-311+G(d,p) level of theory. The isolobal replacement of the Fe(CO)3 with BH fragments leads to the tetrahedranes [Fe(CO)3(BH)(μ-SNH)] 2 and [(HB)2(μ-SNH)] 3. Both were identified by calculations as minima on the respective potential energy surface (PES). However, the tetrahedrane-type structure of 3 is much higher in energy when compared with the planar cyclic isomers 3a and 3b.  相似文献   

2.
The13C and19F NMR spectra ofZ- andE-isomers of β-X-substituted α,β-difluorostyrenes (X=F, Cl, CpFe(CO)2, Re(CO)5, Re2(CO)9Na) were studied. Direct and long-range (across 1–5 bonds) spin-spin coupling constants and the (13C−12C) isotope shifts in the19F NMR spectra were determined. The study of the13C satellites in the19F NMR spectra of substituted difluorostyrenes permitted assignment of the13C NMR signals of the vinylic carbon atoms. Similarly, the signals in19F NMR spectra were assigned based on coupling constants of fluorine withipso-carbon. These assignments were found to be in good agreement with the data available from the literature (X=F, Cl). The developed approach was applied to the elucidation of the structure ofZ−PhCF=CClFe(CO)2Cp. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya. No. 8, pp. 1575–1579, August, 1998.  相似文献   

3.
Single-pulse 13C NMR spectra and spin-lattice relaxation times T1(1H), detected indirectly via 13C carbons, and T1(13C) were measured at 31°C for virgin pelletized and annealed polylactic acid (PLA) samples using the magic-angle spinning technique. The structural relaxation resulting in more regular crystals with narrower conformation distribution and increase in the lamellae thickness and crystallinity brought about by annealing at 100°C was deduced from the narrowing of the 13C NMR lines and proton spin-lattice relaxation times T1(1H). The spin-lattice relaxation times T1(13C) related to the respective carbons of the α-polymorph of PLA are also discussed in the study.  相似文献   

4.
The clusters Fe2(CO)6(μ-XCH2CH=CH2)(μ3-X)Fe(CO)2Cp (X = S, Se) were prepared by the successive treatment of the bi- and trimetallic complexes Fe2(CO)6(μ-Se2) and Fe3(CO)93-X) with allylmagnesium chloride and CpFe(CO)2I. The clusters obtained contain a noncoordinated C=C bond. The structure of the Se-containing cluster was suggested on the basis of comparison of its spectral data (IR,1H NMR, and Mössbauer spectra) with the spectra of the analogous S-containing complex, which was previously characterized by X-ray diffraction analysis.  相似文献   

5.
Multinuclear NMR data (13C, 31P, 13C–{31P}, 13C–{103Rh} and 31P–{103Rh}) for a series of mono- and di-substituted derivatives of Rh6(CO)16 containing neutral two electron donor ligands [Rh6(CO)15L, (L=NCMe, py, cyclooctene, PPh3, P(OPh)3,1/2(μ2,η1:η1-dppe)); Rh6(CO)14(LL), (LL=cis-CH2=CMe-CMe=CH2, dppm, dppe, (P(OPh)3)2)] are reported; these data show that the solid state structure is maintained in solution. Detailed assignments of the 13CO NMR spectra of Rh6(CO)15(PPh3) and Rh6(CO)14(dppm) clusters have been made on the basis 13C–{103Rh} double resonance measurements and the specific stereochemical features of the observed long range couplings in these clusters have been studied. The stereochemical dependence of 3J(P–C) for terminal carbonyl ligands is discussed and the values of 3J(P–C) are found to be mainly dependent on the bond angles in the P–Rh–Rh–C fragment; these data enable the fine structure of the complex multiplets in the 13C–{1H} and 31P–{1H} NMR spectra of Rh6(CO)14 (dppm) to be simulated. Variable temperature 13C–{1H} NMR measurements on Rh6(CO)15(PPh3) reveal the carbonyl ligands in this complex to be fluxional. The fluxional process involves exchange of all the CO ligands except the two terminal CO's associated with the rhodium trans to the substituted rhodium and can be explained by a simple oscillation of the PPh3 on the substituted rhodium atom aided by concomitant exchange of the unique terminal CO on this rhodium with adjacent μ3-CO's.  相似文献   

6.
Ruthenium carbonyl triphenylphosphine complexes Ru2(CO)6−n (PPh3) n {μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} (n=1, 2) were obtained by the reaction of complex Ru2(CO)6{μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} containing the ruthenacyclopentadiene moiety with PPh3 in refluxing toluene. The complexes were characterized by IR and by1H,13C, and31P NMR spectroscopy, and by X-ray analysis. The monophosphine derivative is identical to the complex formed by fragmentation of the Ru3(CO)8(PPh3){μ-C(CH=CHPh)C(Ph)C(CH=CHPh)C(Ph)} cluster and contains the PPh3 ligand at the ruthenium atom of the ruthenacyclopentadiene moiety. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1836–1843, September, 1998  相似文献   

7.
Solid-state 13C nuclear magnetic resonance (13C NMR) with magic-angle spinning (MAS) and with cross-polarization and magic-angle spinning (CP/MAS) spectra, and differential scanning calorimetry (DSC) techniques were used to obtain structural data from a sample of acetyl aleuritolic acid (AAA) extracted from the stem bark of Croton cajucara Benth. (Euphorbiaceae) and recrystallized from acetone. Since solid-state 13C NMR results suggested the presence of more than one molecule in the unitary cell for the AAA, DSC analysis and molecular modeling calculations were used to access this possibility. The absence of phase transition peaks in the DSC spectra and the dimeric models of AAA simulated using the semi-empirical PM3 method are in agreement with that proposal.  相似文献   

8.
The reaction between the dihydride of decacarbonyltriosmium [H2Os3(CO)10] and phenyl arsine oxide (PAO) in benzene yields only one product [Os3(O)9(μ-H){μ-PhAs(O)OAsPh}] (1), which is characterized by high resolution mass spectrometry (HRMS), Fast Atomic Bombardment Mass Spectrometry (FAB)+, IR, 1H and 13C NMR, and single crystal X-ray diffraction. The solid state X-ray diffraction study of compound (1) shows that the molecule is polycyclic and has an osmium triangle with a bridging hydride bonded to a PhAs(O)-O-AsPh ligand.  相似文献   

9.
TG-DTA study of melamine-urea-formaldehyde resins   总被引:2,自引:0,他引:2  
The thermal behaviour of MUF resins from different suppliers with different content of melamine was studied, along with the 13C NMR spectroscopic analysis of resin structure and the testing of particleboards in current production at Estonian PB factory Pärnu Plaaditehas AS. The chemical structure of resins from DMSO-d6 solutions was analysed by 13C NMR spectroscopy on a Bruker AMX500 NMR spectrometer. The melamine level in different MUF resins is compared by the ratios of carbonyl carbon of urea and triazine carbon of melamine in 13C NMR spectra. Curing behaviour of MUF resins was studied by stimultaneous TG-DTA techniques on the Labsys? instrument Setaram. The shape of DTA curves characterisises the resin synthesis procedure by the extent of polymerisation of UF and MF components and is in accordance with structural data.  相似文献   

10.
Two separate samples of Na3C60 were prepared by direct reaction of C60 with sodium metal vapor, and subjected to different annealing times of 10 days and 16 days. Solid-state 13C and 23Na NMR, along with elemental analysis, powder X-ray diffraction (XRD) and Raman spectroscopy, were used to characterize both samples. The Raman spectra of both materials have a single peak at 1447 cm−1 which correspond to the Ag peak of C603−, consistent with the stoichiometry of NaxC60 with x=3. The powder XRD patterns are also virtually identical for both samples. However, solid-state 23Na and 13C NMR spectra of the two samples are significantly different, suggesting a relationship between annealing times and the final structure of the alkali fulleride. Variable-temperature 23Na magic-angle spinning (MAS) NMR experiments reveal the existence of two or three distinct sodium species and reversible temperature-dependent diffusion of sodium ions between octahedral and tetrahedral interstitial sites. 13C MAS NMR experiments are used to identify resonances corresponding to free C60 and fulleride species, implying that the samples are segregated-phase materials composed of C60 and non-stoichiometric Na3C60. Variable-temperature 13C MAS NMR experiments reveal temperature-dependent motion of the fullerides.  相似文献   

11.
Using silicon tetrachloride (SiCl4), tert-butanol (t-BuOH), ethanol (EtOH) and NH3, the hybridized silicon ethoxide 3-tert-butoxide (Si(OEt)x(OBut)4-x) was synthesized and the configuration of the material was investigated by FT-IR,1 H and 13C NMR and gas chromatogram/mass spectrum (GC/MS) techniques. The results confirm that both the ethoxy and the tert-butoxy groups have been attached to silicon atoms. Furthermore, the alkoxy group types and their relative amounts in the alkoxide were also determined by 1H and 13C NMR and GC/MS.  相似文献   

12.
The reaction of Ru3(CO)12 with tetramethyltrifluoromethylcyclopentadiene at various ratios of the reagents was studied. Refluxing of Ru3(CO)12 with a sixfold excess of tetramethyltrifluoromethylcyclopentadiene in octane in an inert atmosphere gave a complex, which is, according to X-ray diffraction data, a dimer,trans-[Ru(η5-C5Me4CF3)(CO)2]2. The reaction under the same conditions but starting from Ru3(CO)12 and C5Me4CF3H in 2∶1 molar ratio gave a hexaruthenium cluster [Ru63-H)(η24-CO)2(μ-CO)(Co)125-C5Me4CF2)], which was characterized by IR as well as1H,13C, and19F NMR spectroscopy. According to X-ray diffraction data, an Ru4 tetrahedron, in which two edges are bound by additional “briding” Ru atoms, constitutes the frame of this compound. This complex has one (η5-C5Me4CF3) ligand, as well as one (μ3-H) and two (η24-CO) groups. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 507–512, March, 1998.  相似文献   

13.
The objective of the present work was to synthesize mononuclear ruthenium complex [RuCl2(CO)2{Te(CH2SiMe3)2}2] (1) by the reaction of Te(CH2SiMe3)2 and [RuCl2(CO)3]2. However, the stoichiometric reaction affords a mixture of 1 and [RuCl2(CO){Te(CH2SiMe3)2}3] (2). The X-ray structures show the formation of the cis(Cl), cis(C), trans(Te) isomer of 1 and the cis(Cl), mer(Te) isomer of 2. The 125Te NMR spectra of the complexes are reported. The complex distribution depends on the initial molar ratio of the reactants. With an excess of [RuCl2(CO)3]2 only 1 is formed. In addition to the stoichiometric reaction, a mixture of 1 and 2 is observed even when using an excess of Te(CH2SiMe3)2. Complex 1 is, however, always the main product. In these cases the 125Te NMR spectra of the reaction solution also indicates the presence of unreacted ligand.  相似文献   

14.
Selective oxidation of one (trans to N) carbonyl group in [Rh(8-Oxiquinolinato)(CO)2] with stoichiometric amount of Me3NO in MeCN produces a solution containing [Rh(Oxq)(CO)(Me3N)] and [Rh(Oxq)(CO)(MeCN)]. The ammonia complex, [Rh(Oxq)(CO)(NH3)], has been prepared by action of NH3 gas on this solution and characterized by IR, 1H and 13C NMR, and X-ray data. Spectral parameters, ν(CO), δ13C, and 1J(CRh), were measured in situ for a series of complexes [Rh(Oxq)(CO)(L)] (L = NAlk3, Py, PBu3, PPh3, P(OPh)3, C8H14) formed upon action of L on [Rh(Oxq)(CO)(NH3)] in THF. A new ν(CO) and δ13C based scale of σ-donor/π-acceptor properties of ligands L is proposed including NH3 and CO as the natural endpoints.  相似文献   

15.
The adsorption and/or decomposition pathway of Fe2(CO)9 or Fe3(CO)12 on hydrated or dehydrated NaY zeolites has been studied by an ESR technique. The adsorption resulted in the formation of three paramagnetic species withg iso=2.0450, 2.0378, and 2.0016, which were attributable to Fe3(CO)11 , Fe2(CO)8 , and Fe(CO)4 anion radicals, respectively. These radicals have been suggested as intermediates in the formation of HFe3(CO)11 on the hydrated NaY zeolite and Fe3(CO)12 on the dehydrated NaY zeolite.  相似文献   

16.
The signals in the13C NMR spectra of 2,3,4,5-tetraphenyl-1-germacyclopenta-2,4-dienes (R1=R2=H, Me,cyclo-C3H5, SiMe3, SnMe3, R1=Me, R2=H, Cl) were completely assigned using 2D NMR spectroscopy. The pattern of the variation of the chemical shifts in the13C NMR spectra indicates that the effects of substituents R1 and R2 on the heterocycle and on the phenyl groups are of inductive rather than mesomeric origin and include the direct through-space polarization of bonds (field effect). Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1962–1965, November, 1997.  相似文献   

17.
The molecule Fe2(CO)7(PhC2Ph)2 has been studied by 13C NMR and is static at ?40°C with a spectrum which is consistent with the known structure observed in the crystals. In the range ?40 to +41°C the three carbonyl resonance coalesce possibly by a single carbonyl averaging process. At room temperature violet Fe3(CO)8(PhC2Ph)2 is found to be static by 13C NMR having a spectrum consistent with the known solid state structure. Dark green Fe3(CO)8(PhC2Ph)2 is static via 13C NMR at ?62°C with a spectrum consistent with the known solid state structure. Between ?62 and +96°C a fluxional process occurs which scrambles the bridge carbonyls and four of the six terminal carbonyl groups. In this process the bridging carbonyls appear to be preferentially moving toward the iron atoms with which they have the shortest iron-carbon bond as observed in the solid state structure.  相似文献   

18.
Reactions of [Et3NH][(μ-MeO2CCH2S)Fe2(CO)6(μ-CO)] in situ generated from the mixture of MeO2CCH2SH, Et3N, and Fe3(CO)12 with 2-C5H4NNCS, 3-C5H4NNCS, and EtNCS in THF, form 1, (μ-MeO2CCH2S)Fe2(CO)5(μ-k2N,S:k2C-2-C5H4NNHCS), 2, (μ-MeO2CCH2S)Fe2(CO)6(μ-k2C,S-3-C5H4NNHCS), and 3, (μ-MeO2CCH2S)Fe2(CO)6(μ-k2C,S-EtNHCS). Reaction of [Et3NH][(μ-PhS)Fe2(CO)6(μ-CO)] in situ formed from the mixture of PhSH, Et3N, and Fe3(CO)12 with EtNCS affords 4, (μ-PhS)Fe2(CO)6(μ-k2C,S-EtNHCS). Reaction of [Et3NH][(μ-EtS)Fe2(CO)6(μ-CO)] in situ produced from the mixture of EtSH, Et3N, and Fe3(CO)12 with EtNCS offers 5, (μ-EtS)Fe2(CO)6(μ-k2C,S-EtNHCS). All new complexes have been fully characterized by EA, IR, 1H NMR, and 13C NMR and structurally determined by X-ray crystallography. Electrochemical studies on 2 and 5 confirm that 2 shows high H2-producing activity.  相似文献   

19.
New complexes of lanthanide nitrates with N, N-diethylantipyrine-4-carboxamide (DEAP), with the general formulae [Ln2(DEAP)3] [NO3]6 (where Ln = La, Pr, Nd, Sm, Tb, Ho, Er, Yb and Y) have been isolated and characterized by chemical analysis and various physical methods such as electrolytic conductance, IR and13C NMR spectral data. Electrolytic conductance values and infrared spectral studies indicate that the nitrate groups are coordinated. Infrared and13C NMR spectral analysis show that the ligand DEAP is coordinated to the tripositive metal ion through the diethylcarboxamide carbonyl and antipyrine carbonyl oxygens in a bidentate fashion.  相似文献   

20.
The P3-nortricyclane 4-methyl-1,2,6-triphosphatricyclo[2.2.1.02,6]heptane, CH3C(CH2P)3, (1), is synthesized in a better yield than earlier described from P4, a Na/K alloy, and CH3C(CH2Br)3 in boiling 1,2-dimethoxyethane. It reacts withM(CO)5 thf (M=Cr, W) in the molar ratios of 1:1, 1:2, and 1:3 to form the pentacarbonylmetal complexes CH3C(CH2P)3[M(CO)5] n [n=1, 2, 3;M=Cr (a), W (b)], (2 a, b–4 a, b).1 gives with Mo(CO)5 thf only mixtures of CH3C(CH2P)3[Mo(CO)5] n andcis-Mo(CO)4 derivatives, which were identified by their infrared active A1 v(CO) modes at 2075 and 2025 cm–1.All the new compounds have been characterized also by their1H{31P},31P{1H} NMR, IR,Raman, and mass spectra.
  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号