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551.
552.
The alternating cooligomers of carbon monoxide and 5-vinyl-2-norbornene have been first synthesized in the presence of catalysts based on palladium complexes containing N^N and P^P ligands. It has been shown that the insertion of carbon monoxide proceeds for the most part via a C(2)-C(3) bond of the norbornene ring. The degree of involvement of both olefinic bonds of diene in alternating copolymerization is decreased when the reaction is carried out in a protic solvent (methanol). The structure of terminal groups of the copolymers depends on the nature of a bidentate ligand and acid.  相似文献   
553.
Oxidative dissolution of nickel in the benzyl halogenide – dipolar aprotic solvent system in the presence of air oxygen proceeds with the formation of benzaldehyde, benzyl alcohol, 1,2-diphenylethane, and trace amounts of 4,4'-ditolyl. Spectrophotometry studies have revealed that the oxidation products are formed in the solution rather than at the nickel surface. It has been shown that the oxygen adsorbed at the nickel surface practically does not pass into the solution.  相似文献   
554.
We have developed preparative methods for the synthesis of substituted fulvenes including inden-2-ylphosphonic acid fragments, as well as aromatic and heterocyclic substituents, based on bis(trimethylsilyl)inden-2-ylphosphonate and substituted azomethines in the presence of sodium hydride as an efficient initiator of the reaction. Subsequent treatment of the phosphonates with methanolic solution of sodium methoxide furnished water-soluble disodium salts of the corresponding phosphonic acids.  相似文献   
555.
Using geometrical and algebraic ideas, we study tunnel eigenvalue asymptotics and tunnel bilocalization of eigenstates for certain class of operators (quantum Hamiltonians) including the case of Penning traps, well known in physical literature. For general hyperbolic traps with geometric asymmetry, we study resonance regimes which produce hyperbolic type algebras of integrals of motion. Such algebras have polynomial (non-Lie) commutation relations with creation-annihilation structure. Over this algebra, the trap asymmetry (higher-order anharmonic terms near the equilibrium) determines a pendulum-like Hamiltonian in action-angle coordinates. The symmetry breaking term generates a tunneling pseudoparticle (closed instanton). We study the instanton action and the corresponding spectral splitting.  相似文献   
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558.
A precision X-ray diffraction study of Nd5Mo3O16 single crystals is performed for the first time at 30 K. Measurements in the range from room temperature to 30K showed that the unit-cell parameters and volume change smoothly. The crystal structure at T = 30 K is similar to that at room temperature. The model of splitting of the atomic positions is confirmed.  相似文献   
559.
Possibility of obtaining low-refractive-index antireflection coatings composed of mesoporous silicon dioxide by simultaneous introduction of two organic compounds, oligoester based on propylene oxide and a nonionogenic surfactant, into a silicon dioxide sol was studied.  相似文献   
560.
The properties of the ruthenium (II) phosphine complexes [Ru(dppe)2(OTs)2] and [Ru{PhP(CH2CH2CH2PPh2)2}(OTs)2] as catalysts of alternating copolymerization of ethylene and carbon monoxide were studied. The catalytic activity of these complexes in the absence of cocatalysis is low, but it is substantially increased in the presence of trifluoroacetic acid or 1,4-benzoquinone. These compounds are the first ruthenium complexes which catalyze copolymerization of ethylene and CO. Translated fromAkademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1119–1121, June, 2000.  相似文献   
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