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1.
Summary Some anomalies in the intensities of the bands of the C=C and C=O bonds in the vibrational spectra of , -unsaturated ketones have been explained by a difference in the sequence of the frequencies of the in-phase (s) and out-of-phase (as) vibrations of the multiple bonds in their cis (s<as) and trans (s>as) arrangements.  相似文献   

2.
Summary The far-i.r. spectra of the title complexes have been examined. Band assignments are based on the shifts induced by ligand deuteration and halide substitution. Deuteration of bipyridine causes large shifts ( >10 cm–1) in internal ligand modes, intermediate shifts between 2 and 9 cm–1) in metal-nitrogen stretching and bending modes and small to zero shifts in metal-halide stretching and bending vibrations. Generally, the requirements for square planarC 2v synanetry [two (M–N) and two (M–X) bands] are observed. Previous ambiguities in the assignment of the (M–N) bands have been resolved by the isotopic labelling technique employed in this study.  相似文献   

3.
Huober  J.  Ruoff  A. 《Structural chemistry》2003,14(2):187-191
The high-resolution FTIR spectrum of the fundamental 8 of borazine 10B3 14N3 1H6 was reanalyzed taking into account the BB resonance with the combination band (10 + 17). A parameter set for the states 8 = 1 and 10 = 17 = 1, respectively, is given, reproducing the observed spectrum at least up to J = 30 with experimental accuracy.  相似文献   

4.
The reaction between Ru3(3-2-PhC2C=CPh)(-dppm)(CO)8 and Co2(CO)8 afforded dark red Co2Ru3(4-C2Ph)(3-C2Ph)(-dppm)(-CO)2(CO)9, shown by an X-ray structure determination to contain a strongly twisted Co2Ru3 bow-tie cluster (central Co), to which two PhC2 units derived from cleavage of the original diyne are attached. One a these is strongly interacting with four metal atoms, the other being attached in the familiar 1,22-mode. The dppm ligand remains bridging two of the Ru atoms.  相似文献   

5.
Zusammenfassung Es wurden Infrarotabsorptionsspektren von NiHPO3·4 H2O und den - und -Isomeren von CoHPO3·2 H2O im Bereich von 700 bis 3600 cm–1 aufgezeichnet und die Banden entsprechend zugeordnet. Aus den Spaltungswerten der Absorptionsbande der antisymmetrischen Valenzschwingung as der PO3-Gruppe folgt, daß durch den Einfluß der Kationen die Symmetrie des Phosphitanions verringert ist, und am besten mit Punktgruppe Cs beschrieben werden kann. Dies wird durch Vergleich der Wellenzahl der symmetrischen Valenzschwingung s (PO2) mit dem nach derRobinsonschen Beziehung ermittelten Wert bestätigt. Aus den Wellenzahlen der Valenzschwingungen s (PO2), as (PO2) und (PO) wurden die Kraftkonstanten und Längen der PO-Bindungen berechnet, die den beim Kupferphosphit und Magnesiumphosphit mittels Röntgenstrukturanalyse ermittelten Werten entsprechen. Aus der Form der Absorptionsbande der Valenzschwingung der OH-Gruppe wurde die Möglichkeit des Vorkommens einer Wasserstoffbindung über ein Wassermolekül diskutiert.
Infrared spectra of nickel and cobalt phosphite
The IR spectra of NiHPO3·4 H2O and of the -and -isomers of CoHPO3·2 H2O have been recorded in the 700–3600 cm–1 region and frequencies assigned. From splitting values of as (PO3) a symmetry decrease of the phosphite anion due to the influence of the cation was found. The symmetry of the phosphite anion therefore is best described under point group Cs. A confirmation was possible by comparing the experimentally obtained symmetric stretching mode s (PO2) with the value calculated from Robinson's equation. Stretching vibration wave numbers were used to calculate force constants and PO-bond lengths; these agree with bond lengths found by X-ray analysis of Cu- and Mg-phosphites. The possible existence of a hydrogen bond due to the presence of a water molecule was discussed on the basis of the shape of the OH bond.


Mit 1 Abbildung  相似文献   

6.
Kinematic viscosities were measured for 2-butanone + 2-butanol binary liquid mixtures with a capillary Ubbelohde routine viscometer in the temperature range from 273.15 to 353.15 K at atmospheric pressure, and covering the whole miscibility field (0xi1). Experimental data have been correlated by means of different empirical or semiempirical relationships, such as =(T), =(xi), and =(T, xi). Viscosity deviations, , from ideal behavior are negative at all experimental conditions, confirming that structure breaking effects prevail in the liquids. Furthermore, the thermodynamics of viscous flow and excess Gibbs energy of activation of viscous flow, G*E, have been calculated. As an alternative and complementary approach to such investigations, the fluidity () of this binary system has been analyzed by the modified—Batschinski theory. The results are discussed in terms of the specific molecular interactions between the mixture components.  相似文献   

7.
Zusammenfassung Die IR-Spektren von mehreren Dioxa- und Diazaboracyclopentanderivaten wurden zusammen mit jenen von C-deuterierten Verbindungen untersucht. Besonderer Wert wurde auf die Klärung von Kopplungen zwischen BN-, BO- und CH3-Schwingungen im Bereich zwischen 1550 bis 1300 cm–1 gelegt.
IR-spectra of several dioxa- and diaza-boracyclopentanes have been studied together with those of some C-deuterated analogues. Special attention has been given to coupling effects of BN-, BO-, and CH3-modes in the 1550–1300 cm–1 region.


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8.
Zusammenfassung In B-Tri(dimethylamino)boroxin zeigt — im Gegensatz zum B-Trimethoxyboroxin — die B–O-Hauptbande nur geringe Kopplung mit CH3-Deformationsschwingungen. Die B–N-Valenzbande tritt hingegen mit sCH3 in Wechselwirkung, wodurch Banden mit gemischtem Schwingungscharakter entstehen. In der deuterierten Verbindung liegt BN verkoppelt mit BO bei 1461 cm–1
In B-Tri(dimethylamino)boroxin coupling between the B–O ring stretching main-band and CH3 is weak in contrast to B-trimethoxyboroxine. Interference between BN and CH3 leads to bands of mixed character, one of them is above 1500 cm–1. In [(CD3)2NBO] BN coupled with BO is at 1461 cm–1.


Mit 2 Abbildungen  相似文献   

9.
Zusammenfassung Mit Hilfe der IR-Spektroskopie wurde nachgewiesen, daß tertiäre Phosphinoxide mit Phenolen über Wasserstoffbrücken zu festen kristallinen Addukten assoziieren. Die Verschiebung der OH-Valenzschwingungsbande des Phenols ( OH) wurde bestimmt, wobei die Substituenten an der Phosphorylgruppe die Lage der Assoziationsbande bestimmen. Die P=O-Valenzschwingungsbande des Phosphinoxids erfährt ebenfalls eine Verschiebung nach einer kleineren Wellenzahl. Die P=O-Werte liegen zwischen 23 und 55 cm–1 je nach eingesetzter phenolischer Verbindung.
IR spectroscopy was used to demonstrate that tertiary phosphine oxides form solid crystalline adducts with phenols by way of hydrogen bonds. The shifts of the bands assigned to the phenolic hydroxyl groups were determined and found to depend on the substitutents of the phosphoryl group. The P=O stretching vibration is also shifted, if this group takes part in hydrogen bonding. The P=O values found range from 23 to 55 cm–1 according to phenols used in adduct formation.
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10.
An interpretation of the IR spectra of kaolinite, dickite, and nacrite is proposed, based on the concept of resonance interaction of two intrasurface hydroxyl groups, and their manifestation in the spectrum as a split doublet 30 cm–1 and by the individual vibration of a third intrasurface OH-group. The structural identification of each band in the IR spectra of the kaolinite minerals is given. It was demonstrated that thermal dehydroxylation under vacuum of kaolinite occurred in two stages with activation energies of 43 and 84 kJ/mole. The activation energy of proton delocalization of the structural hydroxyl groups of kaolinite has been evaluated (E 13 kJ/mole). The contribution of the energy of the interlayer hydrogen bonds (AH 28 kJ/mole) to the total cohesion energy of adjoining layers of kaolinite (Ec 165 kJ/mole) was calculated.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 1, pp. 73–81, January–February, 1985.  相似文献   

11.
The frequency response of a diffusion transducer with gauze electrodes, studied theoretically at high frequencies, is proportional to -3/2 starting with = D/R 2 at < /R 2 and to -1 at > /R 2. Here, = 2f, f is the signal frequency, the electrolyte viscosity, D a diffusion coefficient, and R the radius of the gauze filaments. The calculation is compared with experiment.  相似文献   

12.
Solvent effects on the phase separation of poly(-benzyl L-glutamate) to liquid crystal and isotropic solution have been observed in various helicogenic solvents. The temperature-composition phase diagrams have been determined for each solution. The critical concentrations, 2 * , at which the phase separation occours have been compared in various solvents. In dimethylformamide in which the polymer is molecularly dispersed, the observed 2 * value has agreed with that calculated by Flory's theory. In some solvents in which the polymer aggregates in a head-to-tail mode such as chloroform, the observed 2 * values have been considerably small. It is assumed that the polymer aggregates behave as longer particles than the original particles. In dioxane in which the polymer aggregates highly both in a head-to-tail and a side-by-side modes, the 2 * value has been a little larger than that in chloroform. In this case the relationship between the aggregation and the liquid crystal formation is so complicated that further investigation is necessary. In aromatic solvents such asm-cresol that dissolves the polymer almost molecularly, the 2 * is smaller than that in dimethylformamide. Therefore, the intermolecular interactions between the phenyl groups in the side groups of the polymer and those in solvent molecules must be considered.The author is grateful to Mr. K. Sano and Mr. M. Watanabe for their observation of the liquid crystal formation.  相似文献   

13.
Zusammenfassung Der Vergleich der Spektren von B-Dimethylaminoborazinen mit jenen der entsprechenden B-Hexadeuterodimethylaminoborazine zeigt starke Wechselwirkungen zwischen BN- und CH3-Schwingungen, die ebenso wie in anderen N- und O-Methylborazinen zu einer Frequenzminderung der B–N-Hauptbande führen.
By comparison of the IR-spectra of B-dimethylaminoborazines with those of their hexadeuterodimethylamino analogous shows strong interactions of BN and CH3-frequencies. BN frequencies are decreased like in other O- and N-methylborazines.


Mit 2 Abbildungen  相似文献   

14.
Atranes     
The infrared absorption spectra over the range 400–1700 cm–1 of ten organyl- and organoxysilatranes, p-CH3C6H4O] are investigated. The SiN coordinate link in these compounds is largely unreflected in the fundamental vibration frequencies of the bonds of the central silicon atom or the internal vibration frequencies of the substituents X linked to that atom. However, all the IR spectra have an absorption band in the 570 cm–1 region, related to the valence vibrations (SiN), or manifesting itself as the frequency (Si-O) of the XSi (O)3 group, substantially lowered because of interaction between the Si-O and Si-N bonds. Evidence in favor of this bond is shift of the (Si-H) frequency in the spectrum of silatrane(X=H).For Part V see [1].  相似文献   

15.
The formation of free radicals over the surface of platinum-containing catalysts in the methanol oxidation reaction depending on the temperature, the composition of the reaction mixture, and the procedure used for introducing platinum was studied by the matrix isolation method technique. The nature and transformations of surface intermediates depending on the temperature and the presence of oxygen in the gas phase were studied by Fourier transform IR spectroscopy. The main surface intermediate was the methoxy group. The following three types of these groups were stabilized in alumina-based catalysts: (I) CH3O–Aloct (s(–) = 2806 cm–1), (II) CH3O–Altetr (s(–) = 2825 cm–1), and (III) CH3O < (Al)2 (S(–) = 2845 cm–1, s(–) = 1460 cm–1, s(–) = 1440 cm–1, r || (3) = 1185 cm–1, and (–) = 1095 cm–1). At the same time, isolated methoxy groups (as(–) = 2997 cm–1, as(–) = 2959 cm–1, s(–) = 2857 cm–1, and (3) = 1450 cm–1) and hydrogen-bonded groups ((–) = 3400–3550 cm–1), which resulted from chemisorption at siloxane bridges, were stabilized in silica gel–based catalysts. It was found that CH3O and CH3OO radicals were formed only over the surfaces of pure supports (SiO2 and Al2O3) and their mechanical mixtures with platinum. The total concentration of radicals was described by an extremal function of the composition of reactants, whereas the relative concentration depends on the nature of the support. This is conceivably due to the effect of coordinatively unsaturated cations of the support, which are formed by dehydroxylation in the course of catalyst pretreatment. An increase in the rate of formation of gas-phase radicals on mixed catalysts was explained by special properties of the platinum/support interface region, at which surface intermediates were formed in superequilibrium concentrations under reaction conditions.  相似文献   

16.
The promotion of the branched-chain decomposition of nitrogen trichloride by molecular hydrogen additives at room temperature and 20 torr manifests itself in a decrease in the induction period and the acceleration of reactant consumption with an increase in the hydrogen concentration in the NCl3+ H2+ He mixtures. The emission spectrum of the H2+ NCl3flame contains the intense bands of NCl (b 1+X 3, = 1 – 0, = 0 – 1, and = 0 – 0, where is the vibrational quantum number) and the bands of a hydrogen-free compound. The latter bands can be assigned to electronically excited NCl 2radicals formed in the H + NCl3reaction. The calculations restrict the number of elementary reactions favoring promotion. The promotion effect in the system studied should be due to the side reaction of linear branching. The occurrence of the H + NCl3reaction via two pathways (NHCl + 2Cl and NCl 2+ HCl) ensures the qualitative agreement between the experimental data and calculation.  相似文献   

17.
Summary The tetramethylthiourea (TMTU) complexes of cobalt(II) and nickel(II) halides have been studied in the solid state by electronic, i.r. and far i.r. spectroscopy and magnetochemically. The tetrahedral Co(TMTU)2X2 (X = Cl, Br, 1) and Ni(TMTU)2X2 (X = Cl, Br) complexes have normal magnetic moments, electronic spectra and crystal field parameters; Ni2 (TMTU)3I4 is diamagnetic. The cobalt complexes have normal (CoX) and (CoX) vibrational frequencies. Ni(TMTU)2Cl2 and Ni2(TMTU)3I4 have (NiX) frequencies corresponding to long or bridging Ni-X bonds, while Ni(TMTU)2Br2 has normal (NiBr) frequencies for terminal Ni-Br bonds. The (MS) frequencies are similar to those of cobalt(II) and nickel(II) complexes of other thioureas.  相似文献   

18.
The frequency shift, , of the O—H stretching mode in the IR spectra of the H-complexes of phenol with electron donor molecules BXi (B is the n- or -donor center and Xi are substituents; a total of eight series), the change in the Gibbs free energy, G, due to H-complexation, and the parameter (a measure of the ability of BXi molecules to donate an electron pair; two series) are determined by both the electrostatic interaction and charge transfer in the formation of H-complex. The , G, and values depend not only on the inductive and resonance effects, but also the polarizability of substituents characterized by the parameters.  相似文献   

19.
Conclusions Dipole-dipole interaction of the solvent with molecules of aroyl (hydroxymethyl) trifluorosilanes 4-XC6H4COOCH2SiF3 is responsible for changes in frequency of the stretching vibrations of groups included in a five-membered ring, containing an intramolecular coordination bond Si 0 (the frequencies C=O and SiF a , are lowered, and the frequencies asCOC are raised). The value of the orientation-induction parameter in the Buckingham equation, reflecting the dependence of C=O and SiF a on the parameters of the medium (, n), increases with increasing electron-donor capability of the substituent X, indicating an increase in the strength of the coordination bond. The coefficient in the Hammett equation is determined by the polar properties of the medium.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 10, pp. 2251–2254, October, 1984.  相似文献   

20.
Summary The (5-C5H5)(L)(RN3R)Ni and (5-C5H5)(PPh3)(RN3R)Pd compounds, with L = PPh3, CO, CNR, and RN3R = diaryltriazenido anion, were prepared. The bonding mode of the triazenido ligand is monodentate in the (5-C5H5)(PPh3)(RN3R)M phosphine compounds. The carbonyl and isonitrile groups are inserted into the nickel-nitrogen bond and a five-membered heteronuclear ring is formed in (5-C5-C5H5)(L)(RN3R)Ni, when L= CO and CNR.Most compounds are fluxional, involving site exchange of the triazenidoaryl-groupsvia intermediates with a chelating bonding mode of the triazenido ligand. The (5-C5H5)(PPh3)(RN3R)Ni compound shows anomalous solution paramagnetism, that is correlated with the fluxional mechanism. The temperature dependence of contact shifts in the n.m.r. spectrum was determined and E-values were calculated.  相似文献   

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