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1.
Carbonyl stretching frequencies (ν CO), dipole moments (μ), longwave maxima (λ max), half-wave potentials (° 1/2), and relative intensities ( Z/ Z0) of benzoyl-ion in mass-spectra of trans chalcones and their vinylogues of the general type PhCO(CH=CH) nC 6H 4R-p (I) were measured. Contrary to the previously investigated polyenes of the type R(CH=CH) nR′ (R′ = CHO or COOEt) variation of the substituent R in compounds I has little influence on properties of I in the ground state and a satisfactory linear relationship between (ν CO) or μ and σ constants exists only in the case of I (n = 0, 1); the best correlation with σ + indicates that the mesomeric mechanism plays a great part in the transmission of electronic effects. λ max., E1/2, or Z/ Z0 of all series I (n = 0–3) correlate with σ p or σ 0 constants, and the separation of mesomeric and inductive effects by multiparametric correlation reveals that in this case inductive effect is of great importance in the transmission of electronic effects. These features were accounted for by the non-planar structure of molecules of I, which was confirmed by X-ray analysis of I (R = Br). The Pariser-Parr-Pople method has also been applied to the calculation of π-electronic density in molecules I and it was found that the introduction of various substituents in para position of I exercises a very little influence on the electronic distribution in compounds I. 相似文献
2.
The far infrared spectrum from 370 to 50 cm −1 of gaseous 2-bromoethanol, BrCH 2CH 2OH, was recorded at a resolution of 0.10 cm −1. The fundamental O–H torsion of the more stable gauche ( Gg′) conformer, where the capital G refers to internal rotation around the C–C bond and the lower case g to the internal rotation around the C–O bond, was observed as a series of Q-branch transitions beginning at 340 cm −1. The corresponding O–H torsional modes were observed for two of the other high energy conformers, Tg (285 cm −1) and Tt (234 cm −1). The heavy atom asymmetric torsion (rotation around C–C bond) for the Gg′ conformer has been observed at 140 cm −1. Variable temperature (−63 to −100°C) studies of the infrared spectra (4000–400 cm −1) of the sample dissolved in liquid xenon have been recorded. From these data the enthalpy differences have been determined to be 411±40 cm −1 (4.92±0.48 kJ/mol) for the Gg′/ Tt and 315±40 cm −1 (3.76±0.48 kJ/mol) for the Gg′/ Tg, with the Gg′ conformer the most stable form. Additionally, the infrared spectrum of the gas, and Raman spectrum of the liquid phase are reported. The structural parameters, conformational stabilities, barriers to internal rotation and fundamental frequencies have been obtained from ab initio calculations utilizing different basis sets at the restricted Hartree–Fock or with full electron correlation by the perturbation method to second order. The theoretical results are compared to the experimental results when appropriate. Combining the ab initio calculations with the microwave rotational constants, r0 adjusted parameters have been obtained for the three 2-haloethanols (F, Cl and Br) for the Gg′ conformers. 相似文献
3.
The Schiff base compound, N- N′-bis(4-methoxybenzylidene)ethylenediamine (C 18H 20N 2O 2) has been synthesized and its crystal structure has been investigated by X-ray analysis and PM3 method. The compound crystallizes in monoclinic space group P2 1/ n with a=10.190(1), b=7.954(1), c=10.636(1) Å, β=111.68(1)°, V=801.1(1) Å 3, Z=2 and Dcal=1.229 Mgm −3. The title structure was solved by direct methods and refined to R=0.056 for 2414 reflections [ I>3.0σ( I)] by full-matrix anisotropic least-squares methods. The energy profile of the compound was calculated by PM3 method as a function of θ[N1′–C9′–C9–N1]. The most stable molecular structure of the title compound is the anti conformation, which is different in energy by 5.0 and 1.0 kcal mol −1 from the eclipsed conformation I and gauche conformations, (III and V), respectively. 相似文献
4.
A series of novel heterobimetallic crown ether-like polyoxadiphosphaplatinaferrocenophanes cis-[1,1′-Fc(CH 2O(CH 2CH 2O) nCH 2CH 2PPh 2) 2]PtCl 2 ( n=1–3) (4a–c) was synthesized in good yield by cyclization of the bis(phosphine) ligands 1,1′-Fc(CH 2O(CH 2CH 2O) nCH 2CH 2PPh 2) 2 ( n=1–3) (3a–c) and (PhCN) 2PtCl 2 under high dilution conditions in CH 2Cl 2. The bisphosphines 3a–c are obtained by reaction of the corresponding diols 1,1′-Fc(CH 2O(CH 2CH 2O) nCH 2CH 2OH) 2 ( n=1–3) (1a–c) with: (i) CH 3SO 2Cl in CH 2Cl 2 and (ii) LiPPh 2 in THF. Although the X-ray crystal structure of 4a shows that the cavity is large enough for the encapsulation of small metal cations, inclusion experiments of 4a–c with Group 1 cations, and Mg 2+, or NH 4+ in solution applying NMR titration and cyclovoltammetric methods reveal no evidence for the formation of host–guest complexes for 4a,b. In the case of 4c only the addition of Na + or K + leads to an insignificant effect. 相似文献
5.
Treatment of ruthenium complexes [CpRu(AN) 3][PF 6] (1a) (AN=acetonitrile) with iron complexes CpFe(CO) 2X (2a–2c) (X=Cl, Br, I) and CpFe(CO)L′X (6a–6g) (L′=PMe 3, PMe 2Ph, PMePh 2, PPh 3, P(OPh) 3; X=Cl, Br, I) in refluxing CH 2Cl 2 for 3 h results in a triple ligand transfer reaction from iron to ruthenium to give stable ruthenium complexes CpRu(CO) 2X (3a–3c) (X=Cl, Br, I) and CpRu(CO)L′X (7a–7g) (L′=PMe 3, PMe 2Ph, PMePh 2, PPh 3, P(OPh) 3; X=Br, I), respectively. Similar reaction of [CpRu(L)(AN) 2][PF 6] (1b: L=CO, 1c: P(OMe) 3) causes double ligand transfer to yield complexes 3a–3c and 7a–7h. Halide on iron, CO on iron or ruthenium, and two acetonitrile ligands on ruthenium are essential for the present ligand transfer reaction. The dinuclear ruthenium complex 11a [CpRu(CO)(μ-I)] 2 was isolated from the reaction of 1a with 6a at 0°C. Complex 11a slowly decomposes in CH 2Cl 2 at room temperature to give 3a, and transforms into 7a by the reaction with PMe 3. 相似文献
6.
The new chloro(cyclopentadienyl)silanes Cp′SiH yCl 3−y (Cp′=Me 4EtC 5, y=1: 1; Cp′=Me 4C 5H, y=1: 2; y=0: 3; Cp′=Me 3C 5H 2, y=1: 4 and pentachloro(cyclopentadienyl)disilanes Cp′Si 2Cl 5 (Cp′=Me 5C 5 5, Me 4EtC 5 6, Me 4C 5H 7, Me 3C 5H 2 8, Me 3SiC 5H 4 9) are synthesized in good yields via metathesis reactions. Treatment of 1–9 with LiAlH 4 leads under Cl–H exchange to the hydridosilyl compounds Cp′SiH 3 (Cp′=Me 4EtC 5 10, Me 4C 5H 11, Me 3C 5H 2 12) and to the hydridodisilanyl compounds Cp′Si 2H 5 (Cp′=Me 5C 5 13, Me 4EtC 5 14, Me 4C 5H 15, Me 3C 5H 2 16, Me 3SiC 5H 4 17). Complexes 1–17 are characterized by 1H, 13C, and 29Si-NMR spectroscopy, IR spectroscopy, mass spectrometry and CH-analysis. The structures of 6, 7 and 9 are determined by single-crystal X-ray diffraction analysis. Pyrolysis studies of the cyclopentadienylsilanes 10–12 and disilanes 13–17 show their suitability as precursors in the MOCVD process. 相似文献
7.
139La-NMR chemical shifts were measured for several anionic complexes of formulae Li(C 4H 8O 2) 3/2 [La(ν 3-C 3H 5) 4], [Li(C 4H 8O 2) 2][Cp′ nLa(ν 3-C 3]H 5) 4−n] (Cp′ = Cp(ν 5-C 5H 5); n = 1, 2 and Cp′ = Cp * (ν 5-C 5Me5); N = 1) and Li[R nLa(ν 3-C 3H 4) 4− n] (R = N(SiMe 3) 2; n = 1, 2 and R = CCsIMe 3; n = 4), as well as for neutral compounds for formulae La(ν 3-C 3H 5) 3L n (L = (C 4H 8O 2) 1.5, (HMPT) 2, TMED), Cp′ nLa(ν 3-C 3H 5) 3−n (Cp′= Cp(ν 5-Cp 5H 5), Cp *(ν 5-C 5Me 5); n = 1, 2) and La(ν 3-C 3H 2) 2X(THF) 2 X = Cl, Br, I). Typical ranges of the 139La-NMR chemical shifts were found for the different types of complex independent of number and kind of organyl groups directly bonded to lanthanum. Zusammenfassung139La-NMR-Spektroskopie wurde an einer Reihe anionischer Allyllanthanat(III)-Komplexe der Zusammensetzung
]- [La)ν3-C3H5)4, [Li(C4H8)2][Cp′nLa(ν3-C3H5)4−n(Cp′ = Cp(ν5-C5H5); n = 1, 2 und Cp′ = Cp * (ν5-C5Me5); N = 1) und Li[RnLa(ν3-C3H5)4−n (R = B(SiMe3)2; n = 1, 2 und R = CCSiMe3; n = 4 sowie neutraler Allyllanthan(III)-Komplexe der Zusammensetzung La(ν3-C3H5)3Ln (Ln = (C4H8O2)1.5, (HMPT)2, TMED), Cp′n, La(ν3-C3H5)3−n (Cp′ = Cp(ν5-C5H5), Cp * (ν5- Cp5Me5); n = 1, 2) und La(ν3-Cp3H5)2X(THF)2 (X = Cl, Br, I) durchgefürt. In Abhängikeit von der Anzahl und der Art der am Lanthan gebundenen Gruppen wurden für die verschieden Komplextypen charakteristische Resonanzbereiche ermittelt. 相似文献
8.
Three spiro[pyrrolidine-2,3′-oxindoles], 1,1′,2,2′,5′,6′,7′,7′a-octahydro-2-oxo-1′-phenyl-spiro[3 H-indole-3,3′-[3 H]-pyrrolizine]-2′-carboxylic acid methyl ester (1), 1,1′,2,2′,5′,6′,7′,7′a-octahydro-2-oxo-1′-nitro-2′-phenyl-spiro[3 H-indole-3, 3′-[3 H]-pyrrolizine] (2) and 1,1′,2,2′,5′,6′,7′,7′a-octahydro-2-oxo-1′-nitro-2′-(4″-chlorophenyl)-spiro[3 H-indole-3,3′-[3H]-pyrrolizine] (3) have been synthesized and their 1H, 13C and 15N spectra assigned. The chemical shift assignments are based on Pulsed Field Gradient (PFG) Double Quantum Filter (DQF) 1H, 1H correlation spectroscopy (COSY), PFG 1H, 13C Heteronuclear Multiple Quantum Coherence (HMQC) and PFG 1H,X (X = 13C and 15N) Heteronuclear Multiple Bond Correlation (HMBC) experiments. The single crystal X-ray structures of 1–3 have been determined. Compounds 1 and 2 crystallized in monoclinic space group C2/ c and compound 3 in monoclinic space group P2 1/ c, respectively. Also the ESI-TOF MS data of 1–3 are given. 相似文献
9.
N-2-(4-picolyl)- N′-2-chlorophenylthiourea, 4PicTu2Cl, monoclinic, P2 1/ c, a=10.068(5), b=11.715(2),
β=96.88(4)°,
and Z=4; N-2-(6-picolyl)- N′-2-chlorophenylthiourea, 6PicTu2Cl, triclinic, P-1, a=7.4250(8), b=7.5690(16), c=12.664(3) Å, =105.706(17), β=103.181(13), γ=90.063(13)°, V=665.6(2) Å 3 and Z=2 and N-2-(6-picolyl)- N′-2-bromophenylthiourea, 6PicTu2Br, triclinic, P-1, a=7.512(4), b=7.535(6), c=12.575(4) Å, a=103.14(3), β=105.67(3), γ=90.28(4)°, V=665.7(2) Å 3 and Z=2. The intramolecular hydrogen bonding between N′H and the pyridine nitrogen and intermolecular hydrogen bonding involving the thione sulfur and the NH hydrogen, as well as the planarity of the molecules, are affected by the position of the methyl substituent on the pyridine ring. The enthalpies of fusion and melting points of these thioureas are also affected. 1H NMR studies in CDCl 3 show the NH′ hydrogen resonance considerably downfield from other resonances in their spectra. 相似文献
10.
Carbon–hydrogen bond dissociation enthalpies (BDEs) were computed for all haloethenes, C 2H 4−nX n ( n=0–3, X=F, Cl, Br, I), at the B3LYP/6-311+G(3df,2p) level using isodesmic reactions. It was found that C–H bond strengths in the monohaloethenes varied substantially, by as much as 18 kJ mol −1, dependent upon the bond's stereochemical position relative to the halogen. BDEs in the dihaloethanes varied in the order CX 2CH–H>( E)-CHXCX–H>( Z)-CHXCX–H. Trends in the computed bond enthalpies were discussed and explained on the basis of relative steric repulsions and hyperconjugative delocalization interactions, as determined from Natural Bond Orbital analysis. 相似文献
11.
The complexes (Hal)Nb(CO) 3(PR 3) 3 (PR 3 = PEt 3, Hal = I; PR 3 = PMe 2Ph, Hal = Cl, Br, I) and (Hal)Nb(CO) 4/2(dppe) 1/2 (Hal = Br, I) have been prepared by oxidative halogenation of carbonylniobate with pyridinium halides (Hal = Cl, Br) or iodine (Hal = I). In the tricarbonyls, one CO and one PR 3 are labile and can be displaced by a four-electron donating alkyne to give all-trans-[(Hal)Nb(CO) 2(RCCR′)(PR 3) 2] (PR 3 = PMe 2Ph; Hal = Cl, Br, I: R, R′ = H, Et, Ph; R = H, R′ = Ph. PR 3 = PEt 3, Hal = I: R, R′ = Pr; R = H, R′ = Bu, Ph; R = Me, R′ = Et). In the case of acetylene, INb(CO)(HCCH) 2(PEt 3) 2 is also formed. PR 3 can be displaced by P(OMe) 3. In the tetracarbonyls, two CO ligands are replaced by two isonitriles to form INb(CO) 2(CNR) 2dppe (R = tBu, Cy), or by one alkyne to form (Hal)Nb(CO) 2(PhCCPh)dppe (Hal = Br, I). In these complexes, the remaining CO ligands occupy cis positions. The structure of BrNb(CO) 2(dppe) 2·THF, INb(CO) 2(dppe) 2·hexane and INb(CO) 2(PEt 3) 2(MeCCEt) have been determined by a single crystal X-ray diffraction study. The alkyne complexes are best regarded as octahedral with the centre of the alkyne ligand occupying the positions trans to the halide and the CC axis aligned with the OC---Nb---CO axis. The complexes (Hal)Nb(CO) 2(dppe) 2 adopt a trigonal prismatic structure with the halide capping the tetragonal face spanned by the four phosphorus functions. The crystal structure of a by-product, Br 2Nb(CO)(H 2CPhPCH 2CH 2PPh 2) 2·1/2THF has also been determined. The geometry is pentagonal bipyramidal, with one of the bromine atoms and the CO on the axis. Some 93 Nb NMR data for the Nb I complexes are presented, and preliminary observations on the reactions between the π-alkyne complexes and H 2 or H − are reported. 相似文献
12.
The complexes [M(2,2′-bipyridyl)X 3], with M = Sb, Bi and X = Cl, Br, I, are characterized by long-wavelength metal-to-ligand charge-transfer (MLCT) bands which determine the colours of these compounds in the solid state. The energy of the MLCT bands depends on the reducing strength of the metal and the extent of sp mixing of the lone electron pair at the metal. 相似文献
13.
Using velocity map ion imaging technique, the photodissociation of n-C 4H 9Br in the wavelength range 231–267 nm was studied. The results and our ab initio calculations indicated that the absorption of n-C 4H 9Br in the investigated region originated from the excitations to the lowest three repulsive states, as assigned as 1A″, 2A′ and 3A′ in C s symmetry. Dissociations occurred on the PES surfaces of the three states, terminating in C 4H 9+Br ( 2P 3/2) or C 4H 9 + Br * ( 2P 1/2) as two channels, and being impacted by an avoided crossing between the PES surfaces of the 2A′ and 3A′ states. The transition dipole to the 1A″ state was perpendicular to the symmetry plane, so perpendicular to the C–Br bond. The transitions to the 3A′ state was polarized parallel to the symmetry plane, and also parallel to the C–Br bond. While the transition dipole to the 2A′ state was in the symmetry plane, but formed an angle of about 53.1° with the C–Br bond. We have also determined the avoided crossing probabilities, which affected the relative fractions of the individual pathways, for the photolysis of n-C 4H 9Br near 234 nm and 267 nm. 相似文献
14.
Horseradish peroxidase (HRP) was immobilised on silica gel modified with titanium oxide. This material was employed to prepare modified carbon paste electrode. The direct electron transfer of the hydrogen peroxide reduction by HRP was blocked when immobilised on silica–titanium. This biosensor presented a very sensitive response for phenol (1 μmol l −1) at an applied potential of 0 mV vs SCE. The best condition was achieved in phosphate buffer pH 6.8, ratio of hydrogen peroxide/phenol higher than 0.35. The biosensor showed a linear response range between 10 and 50 μmol l −1 of phenol, adjusted by the equation j=−32.8+16.3 [phenol], for n=5 with a correlation coefficient of 0.9995. The response time of the biosensor was about 3 s. 相似文献
15.
Rotational-state distributions of the CO + (A–X, B–X) and N 2+(B–X) emissions produced by the collisions of He(2 3S) with CO and N 2 were studied in the collision energy ( ER range 100–200 meV. The rotational populations of the emitting states can be fitte by single Boltzmann temperatures ( TR. The TR (320 ± 30 K) for the ν′ = 3 and 4 levels of the CO + (A 2Π) state are nearly independent of, or slightly increase with, ER, while TR for the CO +(B 2Σ +, ν′ = 0) state increases rapidly with ER.The TR (430 ± 20 K) for the N 2+(B 2Σ +, ν′ = 0) state is nearly independent or slightly decreases with increasing ER. Interactions providing these trends are discussed. 相似文献
16.
Fourier transform infrared spectra (4000–400 cm −1) are reported for metal(II) halide 4-vinlypridine complexes of the following stoichiometries: [MX 2(4-vipy] n ( n=4, M=Ni, X=Cl or Br; n=2, M=Cd, X=Cl, Br or I) and assignment are given for all the observed bands. These spectra were compared with X-ray powder diffraction patterns of complexes. It is shown that the proposed structures for these complexes derived from FTIR spectra are consistent with the X-ray powder diffraction measurements and the elemental analysis results. Coordination effect on 4-vinylpyridine has also been investigated. 相似文献
17.
A Doppler-based velocity selection technique has been used to measure the relative velocity dependence of the cross sections σ ji,Δ(ν r) for rotationally inelastic collisions from level ji to ji + Δν 1 = 8,22,42) in 7Li *2 A 1Σ +u)—Xe. The σ jν±2(ν r) are strongly attenuated at a smaller ν r by “torque averaging” due to molecular rotation; in contrast, for large |Δ|, σ jiΔ = ν r−n (1 n 2). An empirical intermolecular potential which reproduces these types of behavior for 3-D classical trajectories is exhibited. 相似文献
18.
Bisphosphonic acids and their salts can be detected after their liquid chromatographic separation by post-column indirect fluorescence detection (IFD). After separation the analyte is combined with the highly fluorescent Al 3+–morin (2′,3,4′,5,7-pentahydroxyflavone) solution and fluorescence decreases because of the formation of the nonfluorescent Al 3+–bisphosphonate complex. The decrease in fluorescence is proportional to the amount of bisphosphonate present. Separation of the multivalent anionic bisphosphonate analytes from other anions and sample matrix is achieved on a strong base anion-exchange column with a strong, basic eluent. The post-column reaction variables, which influence IFD, are identified and optimized for the detection of the bisphosphonates after separation on the anion exchanger. The method is selective, since only a few anions will undergo a reaction with the Al 3+–morin solution, and sensitive, detection limit for difluoromethylene bisphosphonate, F 2MDP, is 4 ng for S/ N=3. The separation–IFD method can be applied to the determination of bisphosphonates, such as F 2MDP, ethane-1-hydroxy-1,1-bisphosphonic acid, dichloromethylene bisphosphonic acid, 4-amino-1-hydroxybutane-1,1-bisphosphonic acid, in biological samples. The separation–IFD method is also applicable to the detection of inositol phosphate anions. 相似文献
19.
The catalytic properties of a series of Fe(II) diimine complexes (diimine= N, N′- o-phenylenebis(salicylideneaminato), N, N′-ethylenebis(salicylideneaminato), N, N′- o-phenylenebisbenzal, N, N′-ethylenebisbenzal) in combination with ethylaluminoxane (EAO) for ethylene oligomerization have been investigated. Treatment of the iron(II) complexes with EAO in toluene generates active catalytic systems in situ that oligomerize ethylene to low-carbon olefins. The effects of reaction temperature, ratios of Al/Fe and reaction periods on catalytic activity and product distribution have been studied. The activity of complex FeCl 2(PhCH= o-NC 6H 4N=CHPh) with EAO at 200°C is 1.35×10 5 g oligomers/mol Fe·h, and the selectivity of C 4–10 olefins is 84.8%. 相似文献
20.
A new complex [Cu (C 4H 7N 3) H 2O (4,4′-Hbpy)]·SO 4·NO 3 was synthesized and X-ray characterized. Elemental analysis, X-ray diffraction and infrared spectroscopy of the complex were performed. The crystal system is orthorhombic. Crystal data: Fw=498.98, spacegroup: P212121. Z=4, a=14.952(3), b=20.491(4), c=6.713 Å. V=2056.7(9) Å. λ(Mo-K)=0.71070 Å. μ=12.18 cm −1, Dcalc=1.66 g/cm 3, F000=1032.00, R=0.062, Rw=0.087. X-ray analysis illustrated that 4,4′-bpy is mono-protonated and that there are two kinds of anions in one molecule, which give rise to the hydrogen interaction between the molecules in the crystal. Then an extended three-dimensional network is formed along the hydrogen bonds and π–π bonds between the pyridine rings. 相似文献
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