Synthesis and Characterization of Thiophenetriptyeene-8-sulfenic Acid

Abstract:

Reaction of the trilithium salt, prepared by treatment of 1,1,1-tris(2-bromo-5-methyl-3-thienyl)ethane, with O,O′-diethyl thiocarbonate gave thiophenetriptycene-8-thiol in 42% yield. The thiol was not oxidized with m-chloroperoxybenzoic acid (MCPBA). However, treatment of the thiol with NaH in THF followed by oxidation with MCPBA gave thiophenetriptycene-8-sulfenic acid in 70% yield. The structure of the sulfenic acid was determined by spectroscopic means and X-ray single-crystal analysis.     

Binuclear trans‐Bis(β‐iminoaryloxy)palladium(II) Complexes Doubly Linked with Pentamethylene Spacers: Structure‐Dependent Flapping Motion and Heterochiral Association Behavior of the Clothespin‐Shaped Molecules

The synthesis, structure, and solution‐state behavior of clothespin‐shaped binuclear trans‐bis(β‐iminoaryloxy)palladium(II) complexes doubly linked with pentamethylene spacers are described. Achiral syn and racemic anti isomers of complexes 1 – 3 were prepared by treating Pd(OAc)₂ with the corresponding N,N′‐bis(β‐hydroxyarylmethylene)‐1,5‐pentanediamine and then subjecting the mixture to chromatographic separation. Optically pure (100 % ee) complexes, (+)‐anti‐ 1 , (+)‐anti‐ 2 , and (+)‐anti‐ 3 , were obtained from the racemic mixture by employing a preparative HPLC system with a chiral column. The trans coordination and clothespin‐shaped structures with syn and anti conformations of these complexes have been unequivocally established by X‐ray diffraction studies. ¹H NMR analysis showed that (±)‐anti‐ 1 , (±)‐anti‐ 2 , syn‐ 2 , and (±)‐anti‐ 3 display a flapping motion by consecutive stacking association/dissociation between cofacial coordination planes in [D₈]toluene, whereas syn‐ 1 and syn‐ 3 are static under the same conditions. The activation parameters for the flapping motion (ΔH^≠ and ΔS^≠) were determined from variable‐temperature NMR analyses as 50.4 kJ mol^?1 and 60.1 J mol^?1 K^?1 for (±)‐anti‐ 1 , 31.0 kJ mol^?1 and ?22.7 J mol^?1 K^?1 for (±)‐anti‐ 2 , 29.6 kJ mol^?1 and ?57.7 J mol^?1 K^?1 for syn‐ 2 , and 35.0 kJ mol^?1 and 0.5 J mol^?1 K^?1 for (±)‐anti‐ 3 , respectively. The molecular structure and kinetic parameters demonstrate that all of the anti complexes flap with a twisting motion in [D₈]toluene, although (±)‐anti‐ 1 bearing dilated Z‐shaped blades moves more dynamically than I‐shaped (±)‐anti‐ 2 or the smaller (±)‐anti‐ 3 . Highly symmetrical syn‐ 2 displays a much more static flapping motion, that is, in a see‐saw‐like manner. In CDCl₃, (±)‐anti‐ 1 exhibits an extraordinary upfield shift of the ¹H NMR signals with increasing concentration, whereas solutions of (+)‐anti‐ 1 and the other syn/anti analogues 2 and 3 exhibit negligible or slight changes in the chemical shifts under the same conditions, which indicates that anti‐ 1 undergoes a specific heterochiral association in the solution state. Equilibrium constants for the dimerizations of (±)‐ and (+)‐anti‐ 1 in CDCl₃ at 293 K were estimated by curve‐fitting analysis of the ¹H NMR chemical shift dependences on concentration as 26 M ^?1 [K_D(racemic)] and 3.2 M ^?1 [K_D(homo)], respectively. The heterochiral association constant [K_D(hetero)] was estimated as 98 M ^?1, based on the relationship K_D(racemic)=1/2 K_D(homo)+1/4 K_D(hetero). An inward stacking motif of interpenetrative dimer association is postulated as the mechanistic rationale for this rare case of heterochiral association.     

Stereospecific polymerization of methacrylonitrile. IV. Polymerization by ate complex-type catalysts

Methacrylonitrile was polymerized by a number of ate-complex catalysts. The catalysts used were NaAlR₄, LiAlR₄, LiZnR₃, Li₂ZnR₄, RMg[AlR₄], and Mg[AlR₄]₂. It was found that the ate-complex catalysts in which one of the alkyls is replaced by a diphenylamino group are capable of producing polymers with higher degrees of crystallinity than those of polymers obtained by unmodified catalysts. It was shown that the diphenylamide linkage in these catalytic systems must play an important role in the steric control in the propagation steps of this type of polymerization, although the mechanism is not clear at present. The crystallinity index used in this research gave a linear relation against I measured by NMR, and can be used as a measure of the stereo-regularity of the polymer.     

Terahertz conductivity measurement of FeSe0.5Te0.5 and Co-doped BaFe2As2 thin films

The terahertz (THz) conductivity of FeSe_0.5Te_0.5 (‘11’-type) and Co-doped BaFe₂As₂ (‘122’-type) thin films are investigated. For ‘11’-type, the frequency dependence of the complex conductivity can be understood as that of BCS-type superconductor near the superconducting gap energy, and we estimated the superconducting gap energy to be 0.6 meV. For ‘122’-type, we estimated the superconducting gap energy to be 2.8 meV, which is considered to be the superconducting gap opened at the electron-type Fermi surface near the M point.     

Highly phosphorescent crystals of vaulted trans-bis(salicylaldiminato)platinum(II) complexes

Unprecedented strong phosphorescent emission in the crystalline state is observed for a variety of vaulted trans-bis(salicylaldiminato)platinum(II) complexes which are newly synthesized as a third coordination mode of well-studied bis(salicylaldiminato) complexes. This Communication describes the dynamic photophysical properties of these complexes in the liquid and crystalline states and a mechanistic rationale for the strong emission in the crystalline state.     

Polarized ethylenes. IV. Synthesis of polarized ethylenes using thioamides and methyl dithiocarboxylates and their application to syntheses of pyrazoles,pyrimidines, pyrazolo[3,4-d]pyrimidines,and 5-aza[2.2.3]cyclazines

Polarized ethylenes having both electron-donating (an amino or a methylthio group) and electron-accepting (cyano, carbamoyl, methyl ester) groups on the adjacent two olefinic carbon atoms were prepared by the condensation of S-alkylthioamidinium salts or methyl dithiocarboxylates with the corresponding active methylene compounds in good yields. These polarized ethylenes were alternatively synthesized by the reaction of thioamides or methyl dithiocarboxylates with tetracyanoethylene oxide in good yields. Reactions of these polarized ethylenes with hydrazine or guanidine derivatives occurred smoothly to give the corresponding pyrazole and pyrimidine derivatives in good yields. The synthesis of 5-aza[2.2.3]cyclazine derivatives using polarized ethylenes is also described.