Radiation-induced addition reaction of carbon tetrachloride onto 1,2-polybutadiene

The γ-ray-induced addition reaction of carbon tetrachloride onto syndiotactic 1,2-polybutadiene film and liquid 1,2-polybutadiene was carried out at room temperature. In the film gelation was pronounced and the rate of addition increased as the crystallinity of the polymer decreased. In the liquid gelation, which makes the polymer insoluble in carbon tetrachloride, did not take place, although a definite crosslinking reaction was noticed. In this case the appearance of the product changed from a viscous liquid to a white powder as the reaction proceeded. Its structure was compared with that of chlorinated 1,2-polybutadiene. The addition of carbon tetrachloride to the vinyl group in liquid 1,2-polybutadiene caused an anti-Markownikoff-type reaction and was accompanied by an unexpectedly large vinyl depletion in the polymer. The total decrease in the vinyl group was found to be much larger than that brought about by the addition of carbon tetrachloride. This discrepancy was attributed to a cyclization and crosslinking reaction ascribed to the vinyl group bound by the main chain. Cyclization and crosslinking were less noticeable in the chlorination than in the carbon tetrachloride.     

Carbonyldinitrosyltris(fluorosulfato)tungstate(II) and ‐Molybdate(II) Anions: Synthesis,Spectroscopy, and Density Functional Theory Calculations

Carbonyldinitrosyltris(fluorosulfato)tungstate(II) and ‐molybdate‐(II) anions, [fac‐M(CO)(NO)₂(SO₃F)₃]^? (M=W, Mo), which are novel weakly coordinating anions that contain a metal carbonyl/nitrosyl moiety, have been generated in fluorosulfonic acid and completely characterized by multinuclear NMR, IR, and Raman spectroscopy as well as ESI mass spectrometry. ESI MS measurements performed for the first time on a superacidic solution system unambiguously reveal the formation of the monoanionic, mononuclear W and Mo complexes formulated as [M(CO)(NO)₂(SO₃F)₃]^? (M=W, Mo). Multinuclear NMR spectroscopic studies at natural abundance and ¹³C and ¹⁵N enrichment clearly indicate the presence of one CO ligand, two equivalent NO ligands, and two types of nonequivalent SO₃F^? groups in a 2:1 ratio. The IR and Raman spectra reveal that the two equivalent NO ligands have a cis conformation, thus indicating a fac structure. Density functional calculations at the B3LYP level of theory predict that these anions have a singlet ground state (¹A′) with a C_s symmetry along with C–O and N–O vibrational frequencies that are in agreement with the experimental observations. Mulliken population analysis shows that the monovalent negative charge is dispersed on the bulky sphere, the surface of which is covered by all the negatively charged O and F atoms with charge densities much lower than SO₃F^?, suggesting that [fac‐M(CO)(NO)₂(SO₃F)₃]^? (M=W, Mo) are weakly nucleophilic and poorly coordinating anions.     

Solvent extraction of permanganates (Na, K) by 18-crown-6 ether from water into 1,2-dichloroethane: elucidation of an extraction equilibrium based on component equilibria

Ion-pair formation constants (K_MLA mol⁻¹ dm³) of Na⁺– and K⁺–18-crown-6 ether (18C6) complexes with MnO₄⁻ in water (w) were determined potentiometrically at 25 °C. Simultaneously, extraction constants (K_ex mol⁻² dm⁶) of the permanganates with 18C6 from w into 1,2-dichloroethane at 25 °C were obtained from the spectrophotometric determination of distribution ratios of the permanganates. These K_ex values were divided into K_MLA and other three component equilibrium constants and thereby extraction-selectivity and -ability were discussed in comparison with corresponding metal picrate–18C6 extraction systems reported before.     

Novel coordinatively unsaturated bimetallic complexes, [(eta5-C5Me5)Ru(mu2-iPrNC(Me)=N(i)Pr)Ru(eta5-C5Me5)]+: a bridging amidinate ligand perpendicular to the metal-metal axis effectively stabilizes the highly reactive cationic diruthenium species.

Coordinatively unsaturated diruthenium complexes, [(eta5-C5Me5)Ru(mu2-iPrNC(Me)=NiPr)Ru(eta5-C5Me5)]+, of which crystallography revealed structures bearing a bridging amidinate ligand perpendicular to the Ru-Ru axis, were synthesized by anion exchange of [(eta5-C3Me5(Ru(mu2-iPrNC(Me)=NiPr)Ru(eta5-C5Me5)]+ Br- by weakly coordinating anions. Variable-temperature NMR showed rapid motion of the bridging amidinate ligand. The coordinatively unsaturated nature of the cationic complexes provides their high reactivity toward a series of two electron donor ligands. Oxidative addition of molecular hydrogen occurred to give [(eta5-C5Me5)Ru(mu2-iPrNC(Me)=NiPr)(mu-H)Ru(eta5-C5Me5)(H)]+, which was isolated and characterized.     

Synthesis of functionalized hydroquinones via [Cp*RuCl2]2-catalyzed cocyclization of alkynes, alpha,beta-unsaturated carbonyl compounds, and carbon monoxide

[reaction: see text] Catalytic [2 + 2 + 1 + 1] cocyclization reaction of an alkyne, an alkene, and two molecules of carbon monoxide, leading to functionalized hydroquinones, was studied. Using [Cp*RuCl2]2 as a catalyst, we found that a variety of electron-deficient alkenes, such as alpha,beta-unsaturated ketones, esters, amides, and nitriles, can be employed as an alkene coupling partner to give the corresponding hydroquinones.     

Microbiological synthesis of 16-ketopregnanes from steroidal sapogenins

Incubation of diosgenone (1, 25D-spirost-4-en-3-one) with Verticillium theobromae (Turconi) Mason et Hughes (CBS) afforded 20α-hydroxypregn-4<ne-3,16-dione (3) and 3α,11β,20α-trihydroxy-5α-pregnan-16-one (4). The same transformation products were also obtained by the use of Stachylidium bicolor Link (IFO 6647). Isolation and identification processes of the products are discussed.     

NMR Spectroscopic Observation of a Metal‐Free Acetylide Anion

A metal‐free acetylide was observed by using NMR spectroscopy. Metal‐free acetylides are closely related to reactive intermediates (carbanions) in solution; therefore, they have been regarded as unobservable species. However, we generated this highly reactive and unstable species through the deprotonation of phenylacetylene by using the strong nonmetallic phosphazene base tBu‐P4. In the presence of tBu‐P4, the J coupling between the ethynyl carbon and hydrogen nuclei (¹J_C,H) of phenylacetylene disappeared; this indicates the deprotonation of the alkyne terminal. Furthermore, a large low‐field shift (approximately 90 ppm) of the alkyne carbon resonance was observed. We concluded that we have observed a metal‐free carbanion with a formal charge on an sp‐hybridized carbon atom for the first time.     

Reaction of [α-(trimethylsilyl)benzyl]ferrocenes with α-ferrocenylbenzyl cations

Although methanolysis of [α-(trimethylsilyl)benzyl]ferrocene (I) and [p-methyl-α-(trimethylsilyl)benzyl]ferrocene (II) in the presence of anhydrous ferric chloride merely gave α-ferrocenylbenzyl methyl ether (III) and p-methyl-α-ferrocenylbenzyl methyl ether (IV), respectively, acid-catalyzed methanolysis of (I) and (II) in the presence of an equimolar amount of (III) or (IV) afforded 1,2-diferrocenyl-l,2-diarylethanes. It is suggested that one electron oxidation of [α-(trimethylsilyl)benzyl]ferrocene by α-ferrocenylbenzyl cation generated from α-ferrocenylbenzyl methyl ether, and subsequent methanolysis of the resulting substituted ferricenium ion may occur to give the two species of α-ferrocenylbenzyl radical, which in turn undergo an approximately statistical coupling.     

Distribution of aquatic plants and absorption of radionuclides by plants through the leaf surface in brackish Lake Obuchi, Japan, bordered by nuclear fuel cycle facilities

We investigated the distribution of aquatic plants and the absorption of radionuclides by them in the brackish Lake Obuchi, Japan, which is bordered by nuclear fuel cycle facilities. We studied 5 species of submerged plants: Zannichellia palustris, Ruppia maritima, Potamogeton pectinatus, Zostera japonica, and Z. marina. The plants contained many elements, including radionuclides. The concentrations of ²³⁸U, ¹³⁷Cs, and ⁹⁰Sr in Z. marina were 11.3-12.4, 0.000-0.144, and 0.151-0.202 Bq^.kg^-1 dw, respectively. Those in Z. japonica were 5.2-8.8, 0.000-0.267, and 0.081-0.175 Bq^.kg^-1 dw, respectively. The concentrations of these radionuclides in the plants tended to be higher in higher-salinity regions than in lower-salinity regions of the lake. We found a close relationship between photosynthetic activity and the absorption of stable Sr by plants in the laboratory. Salinity, illumination, and water temperature influenced the photosynthetic activity of the plants and the consequent absorption of elements.