Effect of Substrates on the Addition Polymerization of 1,4-Benzenedithiol to 1,4-Diethynylbenzene in the Solid State and the Electronic Properties of the Resulting Polymer

The effect of substrates on the addition polymerization of 1,4-benzenedithiol (BDT) to 1,4-diethynylbenzene (DEB) in the solid state and the electronic properties of the polymers obtained were studied. As the substrate polymer sheets, for instance, PET (poly (ethylene terephthalate)) sheet, ON-6 (oriented nylon-6) sheet and so on having surface free energies Γ_s from 27.4 to 55.0 erg/cm² were used. At the monomer sublimation temperature of 60°C, the S wt% (sulfur content) and the cis content of the polymers were not affected by the kind of polymer sheets. However, the molecular weights, M¯_n of the polymers polymerized on the polymer sheets were 13,000–30,000, and the values were several times higher than the molecular weight of the polymers polymerized on glass plate. On the other hand, at the sublimation temperature of 82°C, the cis content of the polymers apparently increased with decreasing d-value of the polymer sheets. On X-ray diffraction patterns of monomer mixtures sublimed onto polymer sheets, the diffraction intensities and the diffraction peak positions were concerned with the d-value of the polymer sheets. Using polymer sheets, the diffraction peak intensities of the monomer mixture at 7.73 and 7.58 Å decreased compared with those on glass plate. In contrast, the peak at 3.65 Å, which is a negligibly small peak on glass plate, obviously increased. However, as the d-value of the polymer sheets (PET 3.45 Å; OPP (oriented polypropylene) 5.2 Å) increased, the diffraction peak intensities at 7.73 Å and 7.58 Å gradually increased and the diffraction peak intensity at 3.65 Å gradually decreased. The parallel electrical conductivities (σ_||) toward the layered structural polymer on PET, ON-6 and glass plate under air atmosphere were 10⁻⁷, 10⁻⁹ and 10⁻¹¹ S/cm, respectively. Under a reduced pressure of 10⁻³ mmHg, the σ_|| values of each polymer lowered by one or two orders of magnitude. On the other hand, the σ_|| values of the nonlayered structural polymers under air atmosphere were about 10⁻¹¹–10⁻¹² S/cm and were independent of the substrates. Even under a reduced pressure of 10⁻³ mmHg, the σ_|| values hardly changed and remained at 10⁻¹¹–10⁻¹² S/cm. The vertical electrical conductivities (σ_⟂) of the layered structural polymers on conductive PET sheet coated by indium tin oxide or NESA glass plates were independent of the substrates and were 10⁻¹⁴ S/cm under air atmosphere. The σ_⟂ values of the nonlayered structural polymers also exhibited the same values. The reversible change of the amount of the layered structural polymer on PET sheet was also caused by irradiation of the photo-light which is the effective wavelength for the phase transition of the polymers mounted on glass plate. The σ_|| value of the layered structural polymer on ON-6 sheet reversibly changed with the amount of the layer structure controlled by the photo-light, that is, the σ_|| increased up to about one order of magnitude by the photo-light at 545.6 nm. On the other hand, the _|| decreased to about one order of magnitude by the photo-light at 539.6 nm. Anisotropic conductivity with respect to σ_|| and σ_⟂, and oxygen doping mechanisms were discussed in relation to the layer structure of polymers. © 1997 John Wiley & Sons, Ltd.     

Dynamic hyperpolarizabilities in Møller–Plesset perturbation theory

As a formulation for calculating the dynamic polarizabilities and hyperpolarizabilities, two different types of the time‐dependent Møller–Plesset perturbation theory (MPPT) are presented: the MPPT in the quasienergy derivative method (QED–MPPT) and the MPPT in the energylike derivative method (ELD–MPPT). The explicit expressions for the response properties in each of these MPPT up to the quadratic response [μ, α(−ω₁, ω₁), β(−ω_σ, ω₁, ω₂)] at an arbitrary correlated order are given. Calculations of the dynamic polarizabilities and hyperpolarizabilities dependent on one frequency at the second‐order MPPT (MP2), in the QED method (QED–MP2) and in the ELD method (ELD–MP2), are examined for 10‐electron systems: hydrogen fluoride and neon. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 71: 251–271, 1999     

Multiple cluster model (MCM) for surface reaction systems

Multiple cluster model (MCM) for investigating surface reactions is formulated. In this model the reaction center, where electron correlation effects often play a key role, is described by an accurate high‐level approximation, and bulk effects such as the lattice distortion energy are evaluated using a simple low‐level approximation. Therefore, the MCM can properly simulate the potential energy hypersurface of the surface reaction system with a feasible computational cost. Since there exists no fixed atom in the MCM, we can rigorously characterize the stationary point (the minimum energy point or the transition state) on the potential energy hypersurface by vibrational frequency analysis. The MCM can be applied not only to surface systems, but also to various large systems. A detailed comparison of the MCM with the integrated molecular orbital+molecular mechanics (IMOMM), the integrated molecular orbital+molecular orbital (IMOMO), and ONIOM developed by Morokuma and co‐workers is also presented. ©1999 John Wiley & Sons, Inc. Int J Quant Chem 71: 403–413, 1999     

Rotational spectrum of the Ar–dimethyl sulfide complex

The rotational spectra of three isotopomers of the Ar–dimethyl sulfide (DMS) complex – normal, ³⁴S, and ¹³C species – were measured in the frequency region from 3.7 up to 24.1 GHz by Fourier transform microwave spectroscopy. The normal species yielded 43 a-type and 79 c-type transitions. No Ar tunneling splitting was observed, while many transitions were split by the internal rotation of the two methyl tops of the DMS unit. In cases where the K-type splitting was close to that due to methyl internal-rotation, several forbidden transitions were observed that followed b-type selection rules. All of the observed transition frequencies were analyzed simultaneously using a phenomenological Hamiltonian also used in previously published work describing the Ar–dimethyl ether (DME) and Ne–DME complexes. The rotational and centrifugal distortion constants and the potential barrier height to methyl-top internal rotation, V₃, were determined. The rotational constants were consistent with an Ar–DMS center of mass (cm) distance of 3.796 (3) Å and a S–cm–Ar angle of 104.8 (2)°. The V₃ potential barrier obtained, 736.17 (32) cm⁻¹, was 97.8% of the DMS monomer barrier. By assuming a Lennard–Jones-type potential, the dissociation energy was estimated to be 2.4 kJ mol⁻¹, which was close to the value for Ar–DME, 2.5 kJ mol⁻¹.     

Dichloro­oxo(quinoline‐8‐thiolato‐κ2N,S)(triphenyl­phosphine oxide‐κO)rhenium(V) acetone solvate

The complex mol­ecule in the title compound, [Re(C₉H₆NS)Cl₂O(C₁₈H₁₅OP)]·C₃H₆O, has distorted octa­hedral geometry. The Re=O bond occupies the position trans to the triphenyl­phosphine oxide O atom. The Re—Cl bond trans to the thiol­ate S atom is longer than that trans to the quinoline N atom, implying a stronger trans influence of the S atom. Intra‐ and inter­molecular π–π inter­actions are also observed between the π rings in the complex.     

Synthesis and Reactivity of Six‐Membered Oxa‐Nickelacycles: A Ring‐Opening Reaction of Cyclopropyl Ketones

Cyclopropanecarboxaldehyde ( 1 a ), cyclopropyl methyl ketone ( 1 b ), and cyclopropyl phenyl ketone ( 1 c ) were reacted with [Ni(cod)₂] (cod=1,5‐cyclooctadiene) and PBu₃ at 100 °C to give η²‐enonenickel complexes ( 2 a – c ). In the presence of PCy₃ (Cy=cyclohexyl), 1 a and 1 b reacted with [Ni(cod)₂] to give the corresponding μ‐η²:η¹‐enonenickel complexes ( 3 a , 3 b ). However, the reaction of 1 c under the same reaction conditions gave a mixture of 3 c and cyclopentane derivatives ( 4 c , 4 c′ ), that is, a [3+2] cycloaddition product of 1 c with (E)‐1‐phenylbut‐2‐en‐1‐one, an isomer of 1 c . In the presence of a catalytic amount of [Ni(cod)₂] and PCy₃, [3+2] homo‐cycloaddition proceeded to give a mixture of 4 c (76 %) and 4 c′ (17 %). At room temperature, a possible intermediate, 6 c , was observed and isolated by reprecipitation at ?20 °C. In the presence of 1,3‐bis(2,6‐diisopropylphenyl)imidazol‐2‐ylidene (IPr), both 1 a and 1 c rapidly underwent oxidative addition to nickel(0) to give the corresponding six‐membered oxa‐nickelacycles ( 6 ai , 6 ci ). On the other hand, 1 b reacted with nickel(0) to give the corresponding μ‐η²:η¹‐enonenickel complex ( 3 bi ). The molecular structures of 6 ai and 6 ci were confirmed by X‐ray crystallography. The molecular structure of 6 ai shows a dimeric η¹‐nickelenolate structure. However, the molecular structure of 6 ci shows a monomeric η¹‐nickelenolate structure, and the nickel(II) 14‐electron center is regarded as having “an unusual T‐shaped planar” coordination geometry. The insertion of enones into monomeric η¹‐nickelenolate complexes 6 c and 6 ci occurred at room temperature to generate η³‐oxa‐allylnickel complexes ( 8 , 9 ), whereas insertion into dimeric η¹‐nickelenolate complex 6 ai did not take place. The diastereoselectivity of the insertion of an enone into 6 c having PCy₃ as a ligand differs from that into 6 ci having IPr as a ligand. In addition, the stereochemistry of η³‐oxa‐allylnickel complexes having IPr as a ligand is retained during reductive elimination to yield the corresponding [3+2] cycloaddition product, which is consistent with the diastereoselectivity observed in Ni⁰/IPr‐catalyzed [3+2] cycloaddition reactions of cyclopropyl ketones with enones. In contrast, reductive elimination from the η³‐oxa‐allylnickel having PCy₃ as a ligand proceeds with inversion of stereochemistry. This is probably due to rapid isomerization between syn and anti isomers prior to reductive elimination.     

An activated catalyst RhH(PPh3)4‐dppe‐ Me2S2 for α‐methylthiolaton of α‐phenyl ketones

In the presence of catalytic amounts of RhH(PPh₃)₄, 1,2‐bis(diphenylphosphino)ethane (dppe), and dimethyl disulfide, cyclic and acyclic α‐phenyl ketones reacted with p‐cyano‐α‐methylthioa‐ cetophenone giving α‐methylthio‐α‐phenylketones. The activated catalyst containing dimethyl disulfide was effective for the α‐methylthiolation reaction of these less reactive substrates. © 2010 Wiley Periodicals, Inc. Heteroatom Chem 22:18–23, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20650     

Generalised energy conservation law for wave equations with variable propagation speed

We investigate the long time behaviour of the L²-energy of solutions to wave equations with variable speed of propagation. The novelty of the approach is the combination of estimates for higher order derivatives of the coefficient with a stabilisation property.     

Open-loop and closed-loop control of dissociative ionization of ethanol in intense laser fields

The relative yield of the C-O bond breaking with respect to the C-C bond breaking in ethanol cation C2H5OH+ is maximized in intense laser fields (10(13)-10(15) Wcm2) by open-loop and closed-loop optimization procedures. In the open-loop optimization, a train of intense laser pulses are synthesized so that the temporal separation between the first and last pulses becomes 800 fs, and the number and width of the pulses within a train are systematically varied. When the duration of 800 fs is filled with laser fields by increasing the number of pulses or by stretching all pulses in a triple pulse train, the relative yield of the C-O bond breaking becomes significantly large. In the closed-loop optimization using a self-learning algorithm, the four dispersion coefficients or the phases of 128 frequency components of an intense laser pulse are adopted as optimized parameters. From these optimization experiments it is revealed that the yield ratio of the C-O bond breaking is maximized as far as the total duration of the intense laser field reaches as long as approximately 1 ps and that the intermittent disappearance of the laser field within a pulse does not affect the relative yields of the bond breaking pathways.