Some anomalies in the vibrational spectra of α, β-unsaturated ketones

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.     

Far infrared spectra (500–50 cm−1) of the 2,2′-bipyridine complexes of palladium and platinum halides

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.     

Infrarotspektren von Nickel- und Kobaltphosphit

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 C_s 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 C_s. 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     

α BB Resonance in the ν8 Band of Borazine –10B

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.     

IR-Spektren von 2,4,6-Tris(dimethylamino)- und 2,4,6-Tris[dimethylamino(d6)]-borazinderivaten

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     

Infrared spectroscopy of hydrogen bond and substituent effects in electron donor molecules

The frequency shift, , of the O—H stretching mode in the IR spectra of the H-complexes of phenol with electron donor molecules BX_i (B is the n- or -donor center and X_i 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 BX_i 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.     

Vibrational isotope effect of linear and planar molecules: Deuterated bromoethenes

Linear (planar) molecules A and B which are identical except for isotopic substitutions at the atomic sites are considered. Stretching (bending, out-of-plane) frequencies _k and normal modes _k of the isotopically perturbed molecule B are expressed in terms of stretching (bending, out-of-plane) frequencies _i and the corresponding normal modes _i of the unperturbed molecule A. Complete specification of the unperturbed normal modes is not required. All that is needed are stretching (bending, out-of-plane) amplitudes | _i of the normal modes _i at those sites that are affected by isotopic substitution. The rule which interlaces frequencies _k of molecule A with frequencies _i of molecule B is derived. Given two isotopic molecules A and B that differ by a single isotopic substitution at site , the inversion relation is derived. This relation expresses unperturbed stretching (bending, out-of-plane) amplitudes at the site in terms of stretching (bending, out-of-plane) frequencies of molecules A and B . As an example, out-of-plane vibrations of deuterated bromoethene were considered. In the simplest method 12 out-of-plane frequencies of four polydeuterated bromoethenes were calculated from 12 out-of-plane frequencies of bromoethene and three monodeuterated bromoethenes. Standard deviation of thus calculated frequencies from experimental frequencies is =2.74 cm^–1. In another method, 15 out-of-plane frequencies of four polydeuterated bromoethenes and selected monodeuterated bromoethene are calculated from 9 out-of-plane frequencies of bromoethene and the remaining two monodeuterated bromoethenes. Depending on which monodeuterated bromoethene is selected (1-, cis- or trans-), standard deviation of thus obtained frequencies from experimental frequencies is 1=2.84 cm^–1, c=2.96 cm^–1 and t=2.72 cm^–1.     

Analysis of the Temperature and Composition Dependence of Viscosimetric Properties of 2-Butanone <Emphasis Type="Bold">+</Emphasis> 2-Butanol Solvent Mixtures

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 (0x_i1). Experimental data have been correlated by means of different empirical or semiempirical relationships, such as =(T), =(x_i), and =(T, x_i). 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.     

Diffuse-Reflectance IR Spectra of Methane Adsorbed on NaZSM-5 and HZSM-5 Zeolites

Diffuse-reflectance IR spectra of methane adsorbed on high-silica NaZSM-5 and HZSM-5 zeolites point to a stronger adsorption of methane on sodium cations than on protons. For the asymmetric stretching vibration ₃, this form of adsorption is characterized by a doublet with band maxima at 2980 and 3010 cm^–1. For the fully symmetric stretching vibration ₁, it is characterized by a singlet with a maximum at 2880 cm^–1. Methane is also adsorbed on NaZSM-5 in a weaker form, which is characterized by absorption bands with maxima at 3002 (₃) and 2887 (₁) cm^–1. The weaker form of methane adsorption on acidic bridging hydroxy groups of HZSM-5 is characterized by absorption bands at 3001 and 2887 cm^–1 (₃ and ₁, respectively). A difference between this form of adsorption and weak adsorption on sodium-exchanged zeolite reveals itself in the somewhat higher intensity of the band at 2887 cm^–1. For methane adsorbed on NaZSM-5, the frequencies of deformational vibrations and a spectrum in the near IR region are obtained for the first time. It was found that the perturbance of adsorbed methane molecules is seen in the spectrum as in the low-frequency shifts of most of the bands that appear due to composite vibrations and overtones and as new adsorption bands that were not observed for gaseous methane.     

Über die Wasserstoffbrückenbindungen zwischen der Phosphorylgruppe und phenolischem Hydroxyl

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.

     

Kinetics of triphenylphosphite ozonide consumption in reaction with triphenylphosphite

Kinetic regularities of triphenylphosphite ozonide reaction with triphenylphosphite have been studied at T=–75°C to –40°C. The rate of ozonide consumption is estimated as W=k₁[(C₆H₅O)₃P·O₃]+k₂[(C₆H₅O)₃P·O₃][(C₆H₅O)₃P], where k₁=(2.03±0.39)×10^–5s^–1(–50°C), 1gk₂=(3.82±0.33)–(6.61±0.32)/gq dm³/mol s and =2.303RT kcal/mol.

---

–75°C –40°C . : W=k₁[(C₆H₅O)₃P·O₃]+k₂[(C₆H₅O)₃P·O₃][(C₆H₅O)₃P], k₁=(2,03±0,39)·10^–5–1(–50°C); 1g k₂=(3,82±0,33)–(6,61±0,32)/ /·, =2,303·RT /

     

IR Spectroscopic Study of Alkane Interaction with the Brønsted Acid Sites of Hydrogen-Exchanged Zeolites

Diffuse-reflectance IR spectroscopy is used to study the interaction of C₃ and C₆ alkanes (propane, n-hexane, 3-methylpentane, and cyclohexane) with the Brønsted acid sites of hydrogen-exchanged mordenite, ferrierite, ZSM-5, and faujasite. It is found that a shift of the absorption band of the stretching vibrations of acidic Si(OH)Al groups toward lower frequencies (OH) due to the formation of a hydrogen bond with adsorbed alkanes increases in the following series: OH(propane) < OH(n-hexane) = OH(3-methylpentane). The accessibility of Si(OH)Al groups to alkane molecules is determined by the dimension of rings through which molecules enter zeolite channels and cavities. It follows from the measured OH values that the strength of Brønsted acid sites decreases in the following series: HZSM-5 > H-mordenite H-ferrierite HY. The difference between the three high-silica zeolites is not great. The results obtained are compared with the published IR data on Si(OH)Al groups of zeolites with adsorbed alkanes and other weak bases.     

Charge control of phenol complexation with unsaturated compounds containing organosilicon substituents. Thiophene derivatives

The frequency shifts of the O-H stretching modes and the resonance components _R of these shifts in the IR spectra of H-complexes of phenol with thiophene derivatives having organic and organosilicon substituents have been analyzed. Relationship of and _R parameters to values calculated by nonempirical methods that characterize the electronic effect of organic substituents on the effective charges of the thiophene ring atoms has been established. It has been shown that in the complexation of phenol (hard acid) with thiophene derivatives charge control prevails over frontier orbital control. The changes in the effective charges of the thiophene ring atoms due to the effect of organosilicon substituents have been calculated.For the previous publication of this series see Ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2163–2168, December, 1994.This work was supported by the Russian Foundation for Basic Research, Project No. 93-03-18725.     

Die IR-Spektren von B-Methoxy- und B-Trideuteromethoxyborazinen und-boroxinen und Tri[methoxy(d3)boran

Zusammenfassung In Methoxyverbindungen des Bors tritt eine Verminderung der Frequenz der B—O-Valenzschwingung gengenüber den entsprechenden Trideuteromethoxyverbindungen auf. Dies wird durch zufällige Entartung von B—O und CH₃ erklärt, die zu einer Abstoßung und zur Vermischung des Schwingungscharakters dieser beiden Schwingungen führt. Hiedurch werden die B—O-Valenzschwingungen zu tieferen und die CH₃-Deformationsschwingungen zu höheren Wellenzahlen verschoben. Ähnliche Erscheinungen sind auch in Methoxyborazinen durch Wechselwirkung von BN und CH₃ zu beobachten. Diese Deutung gibt auch Hinweise für Zuordnungen in den Spektren von N-Methylborazinderivaten.

---

In methoxy substituted boron compounds bands arising from B—O stretching and (O)–CH₃ deformation modes show accidental degeneracy. The frequency of the CH₃ absorption is increased whereas BO is decreased compared to the corresponding CD₃-compounds. The spectra of B-methoxyborazines show similar effects between BN and (O)–CH₃ bands, which is analogous to interference between BN and (N)–CH₃ in N-methylborazines.

---

---

Mit 7 Abbildungen     

IR-Untersuchungen an B-Tris (dimethylamino) boroxin und B-Tris[dimethylamino (d6)] boroxin

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     

Nitrogen Trichloride Decomposition in the Presence of Molecular Hydrogen: I. Promotion of Nitrogen Trichloride Decomposition by Molecular Hydrogen Additives Near the Lower Self-Ignition Limit

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.     

Frequencies and integral intenstities of the lactone and ester carbonyls of natural guaianolides

The frequencies and integral intensities of the IR bands of the stretching vibrations of lactone and acyclic ester carbonyls at C-8 of ten natural guaianolides and their derivatives, and of three model compounds have been studied. The most probable interpretation of the change in the value of A_C=O and _C=O of the lactone carbonyl have been suggested. In elegin and some of its derivatives, acroptilin, chlorohyssopifolin B, and eleganin, a lowering of the values of A_C=0 and _C=0 in comparison with dihydroelegin, hexahydroelegin, and the hydroxylactone of cynaropicrin is caused by nonvalent interactions of the lactone carbonyl with the -exocyclic double bond. The increase in A_C=O and _C=O in dihydroelegin, hexahydroelegen, and the hydroxylactone of cynaropicrin is due to the angular strain of the -lactone ring. It has been shown that in an acyclic side chain at C-8 an increase in the integral intensity and in the frequency of the ,-unsaturated ester carbonyl relative to guaianolides in which the terminal vinyl group at C-17 is absent is due to a conjugation effect.Institute of the Chemistry of Plant Substances, Uzbek SSR Academy of Sciences, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 805–811, November–December, 1987.     

Fluxional nickel(II)- and palladium (II)-triazenido (C5H5)(L)(RN3R)M complexes; Evidence for a triplet-state intermediate

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.     

Study of selective dissociation in C6F5H?C6F5D mixtures induced by intense CO2 laser pulses

Irradiation of a C₆F₅H–C₆F₅D mixture at 1 Torr by a tunable CO₂ pulse laser brings about chiefly dissociation of one component depending on the frequency of emission absorbed by the proper molecules. The addition of radical acceptors increases the selectivity by suppressing secondary reactions.

---

C₆F₅H C₆F₅D 1 CO₂-, , . .

     

Calculation of the quadrupole splitting in 2H NMR spectra of polymeric networks

On the basis of current theories of electric quadrupole effects in NMR, we have calculated the quadrupole splitting in ²H NMR spectra for simple models of polymeric networks. We have considered the effect on of several types of anisotropic motions which are rapid on the NMR time scale: segmental motion; rotations of the deuterium-labeled group about an axis which is fixed relative to the polymeric segment (rotations which are independent of other types of motions); spatially restricted random motion of units of the network relative to their average positions. The calculation predicts an inverse proportionality between and the number of segments of the chain connecting two adjacent units of the network. For the considered systems, in contrast to polycrystals, the lineshape should not depend on the electrostatic field asymmetry parameter which may affect only the magnitude of the splitting . The theory allows us to explain the appearance of an absorption signal of unusual shape in ²H NMR experiments on cross-linked polymers.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 21, No. 1, pp. 56–61, January–February, 1985.