The vibrational ground state rotational spectroscopic constants and structure of the HCN dimer

Rotational spectra have been assigned for four isotopic species of the linear HCN dimer in the vibrational ground state. The spectroscopic constants are

     

2.

Experimental and theoretical study of vibrational spectra and structure of dihalogermylene and dihalostannylene complexes with 1,4-dioxane and triphenylphosphine     

L.A. Leites  A.V. Zabula  S.S. Bukalov  A.A. Korlyukov  P.S. Koroteev  O.S. Maslennikova  M.P. Egorov  O.M. Nefedov 《Journal of Molecular Structure》2005,750(1-3):116-122

Vibrational (Raman and IR) spectra of the 1:1 complexes of dihalogermylene and dihalostannylene with 1,4-dioxane and PPh₃ have been reported, the structures of the complexes Cl₂Ge·C₄H₈O₂ and Cl₂Ge·PPh₃ updated using high-resolution X-ray method. Quantum-chemistry calculations of the geometry and normal mode frequencies and eigenvectors were carried out for some of the complexes. The results show that in the structure of the polymeric solid complexes of X₂M with 1,4-dioxane, intermolecular coordination XM plays a prominent role, whereas the corresponding complexes with PPh₃ are monomeric. In the vibrational spectra of all the complexes, an inversion of symmetric and antisymmetric stretching νXM (X=Cl, Br; M=Ge, Sn) frequencies, found for ‘free’ X₂M^II particles, still persists, suggesting that the X₂M moieties preserve their specifity as carbene analogues also in the complexes.     

3.

One-photon mass-analyzed threshold ionization spectroscopy of 1,3,5-trifluorobenzene: the Jahn-Teller effect and vibrational analysis for the molecular cation in the ground electronic state     

Kwon CH  Kim MS 《The Journal of chemical physics》2004,121(6):2622-2629

One-photon mass-analyzed threshold ionization spectrum of 1,3,5-trifluorobenzene was obtained by using vacuum ultraviolet radiation generated by four-wave difference frequency mixing in Kr. The Jahn-Teller parameters for the e' modes (nu(8)-nu(14)) of 1,3,5-C(6)H(3)F(3)(+) in the ground electronic state needed for spectral analysis were taken from the density functional theory results initially and were upgraded through fits to the experimental results. Excellent agreement was achieved between the experimental and calculated Jahn-Teller energy levels. Assignments of the Jahn-Teller inactive modes were accomplished by referring to the calculated frequencies and the selection rule. The ionization energy of 1,3,5-trifluorobenzene determined from the position of the 0-0 band was 9.6359+/-0.0006 eV.     

4.

Photoinduced Rydberg ionization spectroscopy of phenylacetylene: vibrational assignments of the C state of the cation     

Xu H  Johnson PM  Sears TJ 《The journal of physical chemistry. A》2006,110(25):7822-7825

The photoinduced Rydberg ionization spectrum of the third excited electronic state of phenylacetylene cation was recorded via the origin of the cation ground electronic state. The origin of this state is 17 834 cm(-1) above the ground state of the cation, and the spectrum shows well-resolved vibrational features to the energy of 2200 cm(-1) above this. An assignment of the vibrational structure was made by comparison to calculated frequencies and Franck-Condon factors. From the assignments, and electronic structure considerations, the electronic symmetry of the C state is established to be (2)B(1).     

5.

Detailed analysis of the cation ground state of three dichlorobenzenes by mass analyzed threshold ionization spectroscopy     

Gaber A  Riese M  Grotemeyer J 《Physical chemistry chemical physics : PCCP》2008,10(8):1168-1176

Two color resonant mass analyzed threshold ionization (MATI) spectroscopy was applied in order to investigate the ionic properties of the structural isomers of dichlorobenzene above the ionization threshold. A detailed analysis of the vibrational properties of the two main chlorine isotopomers of each isomer was performed resulting in a precise picture of the vibrational states in the cation ground states. The general features of the two investigated isotopomers turned out to be quite similar, although some vibrational modes are slightly different up to a few wavenumbers, except for the 6b normal mode of p-dichlorobenzene. There the spectrum of the (35)Cl(2)-isotopomer shows several additional peaks compared to the one of the (35)Cl(37)Cl-isotopomer. An explanation for the extraordinary observance is discussed. In addition to the examination of the ionic ground state the measured and calculated frequencies were used to confirm the former assignment of the vibrations in the S(1) state, especially with respect to a Herzberg-Teller coupling as observed in benzene.     

6.

Monte Carlo structure simulations for aqueous 1,4-dioxane solutions     

Nagy PI  Völgyi G  Takács-Novák K 《The journal of physical chemistry. B》2008,112(7):2085-2094

Monte Carlo simulations in the NpT ensembles have been performed for the structure exploration of aqueous 1,4-dioxane solutions. Three different systems with all-atom dioxane:TIP4P water molar compositions of 2:500 (code:D2), 8:465 (D8), and 17:425 (D17) modeled solutions of 0.22, 0.88, and 1.86 mol/dm3 concentrations, respectively, at T = 298 K and p = 1 atm. The calculated solution densities increase from 0.992 to 1.002 g/cm3 with increasing dioxane concentration and approach the experimentally determined densities within 1%. This close agreement was achieved by utilizing RESP charges fitted to the in-solution IEF-PCM/B3LYP/6-31G* electrostatic potential of dioxane taken in its chair conformation and recently developed C, H steric parameters for ethers for calculations with a 12-6-1 all-atom potential. Solution structure analyses pointed out that the dioxane molecules arrange in the solutions with favorable distances of 4-8 angstroms for the ring symmetry centers. Within this range not only pairs of rings but triangular triads and tetrads have also been observed with center-center distances <8 angstroms. For the D8 system, about 25% of the sampled configurations included such a triad. In the case of the D17 model, two simulations starting from different solution configuration predicted different degrees for the dioxane aggregation in aqueous solution. In the more aggregated structure 3-21 triads are consistently maintained and 1-2 tetrads are formed in 58% of the configurations. Each dioxane oxygen forms about one hydrogen bond, on average, to a water molecule in the 0.22-1.86 molar range. The most likely O(dioxane)...H(water) hydrogen bond distance is 1.75-1.80 angstroms compared to the optimal distance of 1.72 angstroms in the isolated dimer. The optimal dioxane-water interaction energy of -5.65 kcal/mol indicates a remarkable hydrogen-bond acceptor character for dioxane.     

7.

Crystal structure of the germanium dichloride complex with 1,4-dioxane     

V. I. Kulishov  N. G. Bokii  Yu. T. Struchkov  O. M. Nefedov  S. P. Kolesnikov  B. L. Perl'mutter 《Journal of Structural Chemistry》1970,11(1):61-64

     

8.

Squeezing the ground vibrational state of diatomic molecules     

Bo Y. Chang  Sungyul Lee  Ignacio R. Sola  Jesus Santamaria 《Journal of photochemistry and photobiology. A, Chemistry》2006,180(3):241-247

We study the squeezing of minimal width vibrational wave packets of diatomic molecules, like Na₂, by using several laser schemes that couple the ground and excited electronic configurations of the molecule. The different schemes imply diabatic and adiabatic laser transformations, or a combination of both, whose efficiency and required physical resources are compared and analyzed.     

9.

The microheterogeneous structure of solutions of cyclohexane, 1,4-dioxane,and morpholine in chlorobenzene     

A. I. Abramovich  L. V. Lanshina 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(7):1147-1153

The data on molecular light scattering, adiabatic compressibility, and molar volume were used to study the special features of the microheterogeneous structure of solutions of cyclohexane, 1,4-dioxane, and morpholine in chlorobenzene at 25°C. The local structure of chlorobenzene experienced rearrangement close to a 0.03 solute mole fractions concentration in all the three systems. Up to a 0.1 mole fractions concentration, the structure of solutions was determined by the solvation of solute molecules. At medium concentrations, microheterogeneity was caused by agglomerates in the first system and agglomerates and conglomerates in the other two systems.     

10.

Gas-phase oxidation of 1,4-dioxane     

F. Battin  G. Scacchi  F. Baronnet 《国际化学动力学杂志》1991,23(10):861-879

An experimental investigation in a conventional static apparatus of the oxidation of equimolecular mixtures 1,4-dioxane-O₂ has shown that 1,4-dioxane reacts with oxygen more readily than most hydrocarbons. Cool flames and ignitions were observed above 200°C in a pressure range up to 300 torr. The products of the slow reaction and cool flame were analyzed by gas chromatography and GC-MS; the slow reaction gives only CO, CO₂, H₂CO, H₂, C₂H₄, and H₂O. A radical chain mechanism is suggested and discussed by using an evaluation of the rate constants of the possible elementary steps by the methods of thermochemical kinetics.     

11.

Crystal and molecular structure of the complex of germanium dibromide with 1,4-dioxane     

T. K. Gar  N. A. Viktorov  S. N. Gurkova  A. I. Gusev  N. V. Alekseev 《Journal of Structural Chemistry》1987,28(1):143-145

     

12.

The chlorobenzene-argon ground state intermolecular potential energy surface     

Munteanu CR  Lopez Cacheiro J  Fernandez B  Makarewicz J 《The Journal of chemical physics》2004,121(3):1390-1396

Using the coupled cluster singles and doubles including connected triple excitations model with the augmented correlation consistent polarized valence double zeta basis set extended with a set of 3s3p2d1f1g midbond functions, we evaluate the ground state intermolecular potential energy surface of the chlorobenzene-argon van der Waals complex. The minima of 420 cm(-1) are characterized by Ar atom position vectors of the length 3.583 A, forming an angle of 9.87 degrees with respect to the axis perpendicular to the chlorobenzene plane. These results are compared to those obtained for similar complexes and to the experimental data available. From the potential the three-dimensional vibrational eigenfunctions and eigenvalues are calculated and the results allow to correct and complete the experimental assignment.     

13.

Mass analyzed threshold ionization spectra of phenol...Ar2: ionization energy and cation intermolecular vibrational frequencies     

Armentano A  Tong X  Riese M  Pimblott SM  Müller-Dethlefs K  Fujii M  Dopfer O 《Physical chemistry chemical physics : PCCP》2011,13(13):6071-6076

The phenol(+)...Ar(2) complex has been characterized in a supersonic jet by mass analyzed threshold ionization (MATI) spectroscopy via different intermediate intermolecular vibrational states of the first electronically excited state (S(1)). From the spectra recorded via the S(1)0(0) origin and the S(1)β(x) intermolecular vibrational state, the ionization energy (IE) has been determined as 68,288 ± 5 cm(-1), displaying a red shift of 340 cm(-1) from the IE of the phenol(+) monomer. Well-resolved, nearly harmonic vibrational progressions with a fundamental frequency of 10 cm(-1) have been observed in the ion ground state (D(0)) and assigned to the symmetric van der Waals (vdW) bending mode, β(x), along the x axis containing the C-O bond. MATI spectra recorded via the S(1) state involving other higher-lying intermolecular vibrational states (σ(s)(1), β(x)(3), σ(s)(1)β(x)(1), σ(s)(1)β(x)(2)) are characterized by unresolved broad structures.     

14.

Nitration of phenol in 1,4-dioxane     

Yu. G. Khabarov  D. E. Lakhmanov  D. S. Kosyakov  N. V. Ul’yanovskii  V. A. Veshnyakov  O. A. Nekrasova 《Russian Journal of Applied Chemistry》2015,88(11):1783-1787

The nitration of phenol with excess nitric acid in aqueous dioxane, in contrast to the nitration in aqueous ethanol, yields exclusively 2,4-dintrophenol, whereas at equimolar ratio of phenol and nitric acid the major reaction products are mononitrophenols (99%), among which the p-isomer prevails.     

15.

Ab initio potential energy surface and excited vibrational states for the electronic ground state of Li2H     

Guosen Yan  Hui Xian  Daiqian Xie 《中国科学B辑(英文版)》1997,40(4):342-347

A 285-point multi-reference configuration-interaction involving single and double excitations (MRS-DCI) potential energy surface for the electronic ground state of Li₂H is determined by using 6-311G (2df, 2pd) basis set. A Simons-Parr-Finlan polynomial expansion is used to fit the discrete surface with a X² of 4.64 × 10^-6. The equilibrium geometry occurs at R_e =0.172 nm and <LiHLi =94.10. The dissociation energy for reaction Li₂H(²A)⇑ Li₂(¹⌆_g)+H(²S) is 243.910 kJ/mol. and that for reaction Li₂H(²A)⇑HLi(¹be)+Li(²S) is 106.445 kJ/mol. The inversion barrier height is 50.388 kJ/mol. The vibrational energy levels are calculated using the discrete variable representation (DVR) method. Project supported by the National Natural Science Foundation of China (grant No. 29673029) and by the Special Doctoral Research Foundation of the State Education Commission of China.     

16.

Ab initio potential energy surface and excited vibrational states for the electronic ground state of Li_2H     

鄢国森  先晖  谢代前 《中国科学B辑(英文版)》1997,(4)

A 285-pomt multi-reference configuration-interaction involving single and double excitations ( MRS DCI) potential energy surface for the electronic ground state of L12H is determined by using 6-311G (2df,2pd)basis set.A Simons-Parr-Finlan polynomial expansion is used to fit the discrete surface with a x2 of 4.64×106 The equn librium geometry occurs at Rc=0.172 nm and,LiHL1=94.10°.The dissociation energy for reaction I2H(2A)→L12(1∑g)+H(2S) is 243.910 kJ/mol,and that for reaction L12H(2A')→HL1(1∑) + L1(2S) is 106.445 kl/mol The inversion barrier height is 50.388 kj/mol.The vibrational energy levels are calculated using the discrete variable representation (DVR) method.     

17.

Homolytic amination of benzo-1,4-dioxane     

L. N. Zorina  O. G. Safiev  D. L. Rakhmankulov 《Chemistry of Heterocyclic Compounds》1989,25(3):261-263

When 5,6-benzo-1,4-dioxane was reacted with N,N-dialkylchloramines in the presence of FeSO₄ at 10–20C in a solution of acetic and sulfuric acids, 6-(N,N-dialkylamino)benzo-1,4-dioxanes and 6-chloro- and 6,7-dichloro-benzo-1,4-dioxanes were obtained. Under the conditions used in the study mainly chlorination products were synthesized. Reaction of 5,6-benzo-1,4-dipxane with the system (NH₃OH)₂SO₄-TiCl₃ resulted in the formation of 6-aminobenzo-1,4-dioxane.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 316–318, March, 1989.     

18.

1,4-二氧六环的光电离解离     

邹鹏  吴国盛  陈文武  杨达林  盛六四  武国华  叶为全  张允武 《物理化学学报》1998,14(1):21-26

采用同步辐射光源、飞行时间质谱和分子束方法研究了1．4-二氧六环的光电离解离过程．由光电离效率曲线得出离子产物的出现势，计算了产物的生成焓．若重分析了m／e=28,29.41等离子碎片的解离通道以及离子碎片的可能结构，提出1、4-二氧六环在光电离解离过程中发生了重排反应     

19.

Synthesis of acetylenic derivatives of 1,4-dioxane     

S. G. Grigoryan  K. G. Avetisyan  A. M. Arzumanyan  A. A. Mkrtchyan  A. A. Matnishyan 《Chemistry of Heterocyclic Compounds》1986,22(8):828-829

Cyclic ketals — 2,5-dimethyl-2,5-bis(4-penten-2-ynyloxy)-1,4-dioxane and 2,5-dimethyl-2,5-bis(3-phenyl-2-propynyloxy)-1,4-dioxane — were isolated in the reaction of propargyl alcohol with vinyl- and phenylethynylcarbinols in the presence of HgO-BF₃.O(C₂H₅)₂ catalytic system.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1029–1030, August, 1986.     

20.

Vibrational spectroscopy of the pyridazine cation in the ground state     

Choi KW  Ahn DS  Lee JH  Kim SK 《The journal of physical chemistry. A》2006,110(8):2634-2638

Vibrational structure of the pyridazine cation in the ground state has been revealed by a vacuum-ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopy. The adiabatic ionization energy is precisely measured to be 70241 +/- 6 cm(-1) (8.7088 +/- 0.0007 eV). The origin is very weakly observed, while a long progression of the nu9(+) (a1) band of which the fundamental vibrational frequency is 647 cm(-1) is predominantly observed. The nu9(+) (a1) mode progression combined with one quantum of the nu3(+) (a1) band at 1698 cm(-1) is found to be even stronger. Many other weakly observed vibrational features of the pyridazine cation are identified in the vibrational energy of 0-3500 cm(-1). The structural change of pyridazine upon ionization, reflected in the vibrational spectrum obtained by the one-photon direct ionization process, is theoretically predicted by ab initio calculations. Ring distortion including contraction of the N=N bond should be responsible for strong excitations of nu3(+) and nu9(+) modes. Franck-Condon analysis is given for the comparison of the experiment and theory.     

isotope	-B0 (MHz)	DJ (kHz)	xN1 (MHz)	xN2 (MHz)
HC14N-HC14N	1745.80973(50)	2.133(30)	?4.0973(200)	?4.4400(190)
HC14N-HC15N	1700.30190(30)	1.939(40)	?4.1059(10)	-
HC15N-HC14N	1729.92082(20)	2.023(30)	-	?4.4339(6)
HC15N-HC15N	1684.28825(25)	1.900(30)	-	-

Experimental and theoretical study of vibrational spectra and structure of dihalogermylene and dihalostannylene complexes with 1,4-dioxane and triphenylphosphine

Vibrational (Raman and IR) spectra of the 1:1 complexes of dihalogermylene and dihalostannylene with 1,4-dioxane and PPh₃ have been reported, the structures of the complexes Cl₂Ge·C₄H₈O₂ and Cl₂Ge·PPh₃ updated using high-resolution X-ray method. Quantum-chemistry calculations of the geometry and normal mode frequencies and eigenvectors were carried out for some of the complexes. The results show that in the structure of the polymeric solid complexes of X₂M with 1,4-dioxane, intermolecular coordination XM plays a prominent role, whereas the corresponding complexes with PPh₃ are monomeric. In the vibrational spectra of all the complexes, an inversion of symmetric and antisymmetric stretching νXM (X=Cl, Br; M=Ge, Sn) frequencies, found for ‘free’ X₂M^II particles, still persists, suggesting that the X₂M moieties preserve their specifity as carbene analogues also in the complexes.     

One-photon mass-analyzed threshold ionization spectroscopy of 1,3,5-trifluorobenzene: the Jahn-Teller effect and vibrational analysis for the molecular cation in the ground electronic state

One-photon mass-analyzed threshold ionization spectrum of 1,3,5-trifluorobenzene was obtained by using vacuum ultraviolet radiation generated by four-wave difference frequency mixing in Kr. The Jahn-Teller parameters for the e' modes (nu(8)-nu(14)) of 1,3,5-C(6)H(3)F(3)(+) in the ground electronic state needed for spectral analysis were taken from the density functional theory results initially and were upgraded through fits to the experimental results. Excellent agreement was achieved between the experimental and calculated Jahn-Teller energy levels. Assignments of the Jahn-Teller inactive modes were accomplished by referring to the calculated frequencies and the selection rule. The ionization energy of 1,3,5-trifluorobenzene determined from the position of the 0-0 band was 9.6359+/-0.0006 eV.     

Photoinduced Rydberg ionization spectroscopy of phenylacetylene: vibrational assignments of the C state of the cation

The photoinduced Rydberg ionization spectrum of the third excited electronic state of phenylacetylene cation was recorded via the origin of the cation ground electronic state. The origin of this state is 17 834 cm(-1) above the ground state of the cation, and the spectrum shows well-resolved vibrational features to the energy of 2200 cm(-1) above this. An assignment of the vibrational structure was made by comparison to calculated frequencies and Franck-Condon factors. From the assignments, and electronic structure considerations, the electronic symmetry of the C state is established to be (2)B(1).     

Detailed analysis of the cation ground state of three dichlorobenzenes by mass analyzed threshold ionization spectroscopy

Two color resonant mass analyzed threshold ionization (MATI) spectroscopy was applied in order to investigate the ionic properties of the structural isomers of dichlorobenzene above the ionization threshold. A detailed analysis of the vibrational properties of the two main chlorine isotopomers of each isomer was performed resulting in a precise picture of the vibrational states in the cation ground states. The general features of the two investigated isotopomers turned out to be quite similar, although some vibrational modes are slightly different up to a few wavenumbers, except for the 6b normal mode of p-dichlorobenzene. There the spectrum of the (35)Cl(2)-isotopomer shows several additional peaks compared to the one of the (35)Cl(37)Cl-isotopomer. An explanation for the extraordinary observance is discussed. In addition to the examination of the ionic ground state the measured and calculated frequencies were used to confirm the former assignment of the vibrations in the S(1) state, especially with respect to a Herzberg-Teller coupling as observed in benzene.     

Monte Carlo structure simulations for aqueous 1,4-dioxane solutions

Monte Carlo simulations in the NpT ensembles have been performed for the structure exploration of aqueous 1,4-dioxane solutions. Three different systems with all-atom dioxane:TIP4P water molar compositions of 2:500 (code:D2), 8:465 (D8), and 17:425 (D17) modeled solutions of 0.22, 0.88, and 1.86 mol/dm3 concentrations, respectively, at T = 298 K and p = 1 atm. The calculated solution densities increase from 0.992 to 1.002 g/cm3 with increasing dioxane concentration and approach the experimentally determined densities within 1%. This close agreement was achieved by utilizing RESP charges fitted to the in-solution IEF-PCM/B3LYP/6-31G* electrostatic potential of dioxane taken in its chair conformation and recently developed C, H steric parameters for ethers for calculations with a 12-6-1 all-atom potential. Solution structure analyses pointed out that the dioxane molecules arrange in the solutions with favorable distances of 4-8 angstroms for the ring symmetry centers. Within this range not only pairs of rings but triangular triads and tetrads have also been observed with center-center distances <8 angstroms. For the D8 system, about 25% of the sampled configurations included such a triad. In the case of the D17 model, two simulations starting from different solution configuration predicted different degrees for the dioxane aggregation in aqueous solution. In the more aggregated structure 3-21 triads are consistently maintained and 1-2 tetrads are formed in 58% of the configurations. Each dioxane oxygen forms about one hydrogen bond, on average, to a water molecule in the 0.22-1.86 molar range. The most likely O(dioxane)...H(water) hydrogen bond distance is 1.75-1.80 angstroms compared to the optimal distance of 1.72 angstroms in the isolated dimer. The optimal dioxane-water interaction energy of -5.65 kcal/mol indicates a remarkable hydrogen-bond acceptor character for dioxane.     

Squeezing the ground vibrational state of diatomic molecules

We study the squeezing of minimal width vibrational wave packets of diatomic molecules, like Na₂, by using several laser schemes that couple the ground and excited electronic configurations of the molecule. The different schemes imply diabatic and adiabatic laser transformations, or a combination of both, whose efficiency and required physical resources are compared and analyzed.     

The microheterogeneous structure of solutions of cyclohexane, 1,4-dioxane,and morpholine in chlorobenzene

The data on molecular light scattering, adiabatic compressibility, and molar volume were used to study the special features of the microheterogeneous structure of solutions of cyclohexane, 1,4-dioxane, and morpholine in chlorobenzene at 25°C. The local structure of chlorobenzene experienced rearrangement close to a 0.03 solute mole fractions concentration in all the three systems. Up to a 0.1 mole fractions concentration, the structure of solutions was determined by the solvation of solute molecules. At medium concentrations, microheterogeneity was caused by agglomerates in the first system and agglomerates and conglomerates in the other two systems.     

Gas-phase oxidation of 1,4-dioxane

An experimental investigation in a conventional static apparatus of the oxidation of equimolecular mixtures 1,4-dioxane-O₂ has shown that 1,4-dioxane reacts with oxygen more readily than most hydrocarbons. Cool flames and ignitions were observed above 200°C in a pressure range up to 300 torr. The products of the slow reaction and cool flame were analyzed by gas chromatography and GC-MS; the slow reaction gives only CO, CO₂, H₂CO, H₂, C₂H₄, and H₂O. A radical chain mechanism is suggested and discussed by using an evaluation of the rate constants of the possible elementary steps by the methods of thermochemical kinetics.     

The chlorobenzene-argon ground state intermolecular potential energy surface

Using the coupled cluster singles and doubles including connected triple excitations model with the augmented correlation consistent polarized valence double zeta basis set extended with a set of 3s3p2d1f1g midbond functions, we evaluate the ground state intermolecular potential energy surface of the chlorobenzene-argon van der Waals complex. The minima of 420 cm(-1) are characterized by Ar atom position vectors of the length 3.583 A, forming an angle of 9.87 degrees with respect to the axis perpendicular to the chlorobenzene plane. These results are compared to those obtained for similar complexes and to the experimental data available. From the potential the three-dimensional vibrational eigenfunctions and eigenvalues are calculated and the results allow to correct and complete the experimental assignment.     

Mass analyzed threshold ionization spectra of phenol...Ar2: ionization energy and cation intermolecular vibrational frequencies

The phenol(+)...Ar(2) complex has been characterized in a supersonic jet by mass analyzed threshold ionization (MATI) spectroscopy via different intermediate intermolecular vibrational states of the first electronically excited state (S(1)). From the spectra recorded via the S(1)0(0) origin and the S(1)β(x) intermolecular vibrational state, the ionization energy (IE) has been determined as 68,288 ± 5 cm(-1), displaying a red shift of 340 cm(-1) from the IE of the phenol(+) monomer. Well-resolved, nearly harmonic vibrational progressions with a fundamental frequency of 10 cm(-1) have been observed in the ion ground state (D(0)) and assigned to the symmetric van der Waals (vdW) bending mode, β(x), along the x axis containing the C-O bond. MATI spectra recorded via the S(1) state involving other higher-lying intermolecular vibrational states (σ(s)(1), β(x)(3), σ(s)(1)β(x)(1), σ(s)(1)β(x)(2)) are characterized by unresolved broad structures.     

Nitration of phenol in 1,4-dioxane

The nitration of phenol with excess nitric acid in aqueous dioxane, in contrast to the nitration in aqueous ethanol, yields exclusively 2,4-dintrophenol, whereas at equimolar ratio of phenol and nitric acid the major reaction products are mononitrophenols (99%), among which the p-isomer prevails.     

Ab initio potential energy surface and excited vibrational states for the electronic ground state of Li2H

A 285-point multi-reference configuration-interaction involving single and double excitations (MRS-DCI) potential energy surface for the electronic ground state of Li₂H is determined by using 6-311G (2df, 2pd) basis set. A Simons-Parr-Finlan polynomial expansion is used to fit the discrete surface with a X² of 4.64 × 10^-6. The equilibrium geometry occurs at R_e =0.172 nm and <LiHLi =94.10. The dissociation energy for reaction Li₂H(²A)⇑ Li₂(¹⌆_g)+H(²S) is 243.910 kJ/mol. and that for reaction Li₂H(²A)⇑HLi(¹be)+Li(²S) is 106.445 kJ/mol. The inversion barrier height is 50.388 kJ/mol. The vibrational energy levels are calculated using the discrete variable representation (DVR) method. Project supported by the National Natural Science Foundation of China (grant No. 29673029) and by the Special Doctoral Research Foundation of the State Education Commission of China.     

Ab initio potential energy surface and excited vibrational states for the electronic ground state of Li_2H

A 285-pomt multi-reference configuration-interaction involving single and double excitations ( MRS DCI) potential energy surface for the electronic ground state of L12H is determined by using 6-311G (2df,2pd)basis set.A Simons-Parr-Finlan polynomial expansion is used to fit the discrete surface with a x2 of 4.64×106 The equn librium geometry occurs at Rc=0.172 nm and,LiHL1=94.10°.The dissociation energy for reaction I2H(2A)→L12(1∑g)+H(2S) is 243.910 kJ/mol,and that for reaction L12H(2A')→HL1(1∑) + L1(2S) is 106.445 kl/mol The inversion barrier height is 50.388 kj/mol.The vibrational energy levels are calculated using the discrete variable representation (DVR) method.     

Homolytic amination of benzo-1,4-dioxane

When 5,6-benzo-1,4-dioxane was reacted with N,N-dialkylchloramines in the presence of FeSO₄ at 10–20C in a solution of acetic and sulfuric acids, 6-(N,N-dialkylamino)benzo-1,4-dioxanes and 6-chloro- and 6,7-dichloro-benzo-1,4-dioxanes were obtained. Under the conditions used in the study mainly chlorination products were synthesized. Reaction of 5,6-benzo-1,4-dipxane with the system (NH₃OH)₂SO₄-TiCl₃ resulted in the formation of 6-aminobenzo-1,4-dioxane.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 316–318, March, 1989.     

1,4-二氧六环的光电离解离

采用同步辐射光源、飞行时间质谱和分子束方法研究了1．4-二氧六环的光电离解离过程．由光电离效率曲线得出离子产物的出现势，计算了产物的生成焓．若重分析了m／e=28,29.41等离子碎片的解离通道以及离子碎片的可能结构，提出1、4-二氧六环在光电离解离过程中发生了重排反应     

Synthesis of acetylenic derivatives of 1,4-dioxane

Cyclic ketals — 2,5-dimethyl-2,5-bis(4-penten-2-ynyloxy)-1,4-dioxane and 2,5-dimethyl-2,5-bis(3-phenyl-2-propynyloxy)-1,4-dioxane — were isolated in the reaction of propargyl alcohol with vinyl- and phenylethynylcarbinols in the presence of HgO-BF₃.O(C₂H₅)₂ catalytic system.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1029–1030, August, 1986.     

Vibrational spectroscopy of the pyridazine cation in the ground state

Vibrational structure of the pyridazine cation in the ground state has been revealed by a vacuum-ultraviolet mass-analyzed threshold ionization (VUV-MATI) spectroscopy. The adiabatic ionization energy is precisely measured to be 70241 +/- 6 cm(-1) (8.7088 +/- 0.0007 eV). The origin is very weakly observed, while a long progression of the nu9(+) (a1) band of which the fundamental vibrational frequency is 647 cm(-1) is predominantly observed. The nu9(+) (a1) mode progression combined with one quantum of the nu3(+) (a1) band at 1698 cm(-1) is found to be even stronger. Many other weakly observed vibrational features of the pyridazine cation are identified in the vibrational energy of 0-3500 cm(-1). The structural change of pyridazine upon ionization, reflected in the vibrational spectrum obtained by the one-photon direct ionization process, is theoretically predicted by ab initio calculations. Ring distortion including contraction of the N=N bond should be responsible for strong excitations of nu3(+) and nu9(+) modes. Franck-Condon analysis is given for the comparison of the experiment and theory.