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排序方式: 共有366条查询结果,搜索用时 15 毫秒
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G. V. Gavrilova A. A. Aleshkin V. A. Nikanorov D. P. Krut'ko V. I. Rozenberg O. A. Reutov 《Russian Chemical Bulletin》1995,44(3):502-506
A novel method for the synthesis of the oxime of 4-methyl-2,4,6-cycloheptatrien-1-one (Eschenmoser's oxime) is proposed. The method involves redox enlargement of the ring of 4-dibromomethyl-4-methyl-2,5-cyclohexadien-1-one oxime through the action of Ni(PPh3)4 in DMF (in the presence of Zn). The product is formed as a mixture ofsyn- andanti-forms readily interconverting in solutions. A similar reaction of 4-methyl-4-trichloromethyl-2,5-cyclohexadien-1-one oxime afforded the dimer of agem--centered semiquinoid carbene (1,2-bis-(1-methyl-4-oxyimino-2,5-cyclohexadienyl)-1,2-dichloroethylene), together withsyn- andanti-isomers of 4-chloro-5-methyl-2,4,6-cycloheptatrien-1-one oxime, which are readily separable but also quickly interconverting in solutions. For the latter compounds, the complete1H NMR assignment of the stereoisomeric structures has been carried out.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 519–523, March, 1995.The authors are grateful to the International Science Foundation (Grant MHW000) as well as the Russian Foundation for Basic Research (Project No. 94-03-08873) for the financial support of the work. 相似文献
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The synthesis of a new ligand system for mono- and bimetallic complexes based on a calixarene is described. Ligand BBPC (3, bis(bipyridine)-calix[4]arene) is obtained in three steps in 40% overall yield by first brominating one of the methyl groups of the 4,4'-dimethyl-2,2'-bipyridine in two steps and subsequently reacting it with p-tert-butylcalix[4]arene under basic conditions. Reaction of BBPC (3) with 2 equiv of [Rh(NBD)(2)]BF(4) or [Rh(NBD)(CH(3)CN)(2)]BF(4) (NBD = norbornadiene) produces the bimetallic compound BBPC[Rh(NBD)BF(4)](2) (4). Treatment of the ligand with PdCl(2)(CH(3)CN)(2) leads to the isolation of the bimetallic complex BBPC[PdCl(2)](2) (5). When the nickel precursor NiBr(2)(DME) (DME = dimethoxyethane) is reacted with BBPC, the bimetallic complex BBPC[NiBr(2)](2) (6) is isolated which, upon crystallization from methanol, gives the mononuclear bis(bipyridine) complex BBPC[NiBr(OMe)] (7). Full characterization includes X-ray structural studies of complexes 4, 5, and 7. The bimetallic compounds 4 and 5 show metal to metal distances of 4.334 A (for 4) and 3.224 A (for 5). For all three complexes, unique molecular packing arrangements were found, based on hydrophobic/hydrophilic interactions. 相似文献
5.
Poverenov E Gandelman M Shimon LJ Rozenberg H Ben-David Y Milstein D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2004,10(19):4673-4684
Novel anionic dialkyl, diaryl, and dihydride platinum(II) complexes based on the new "long-arm" hemilabile PCN-type ligand C6H4[CH2P(tBu)2](CH2)2N(CH3)2 with the general formula Li+[Pt(PCN)(R)2]- (R=Me (4), Ph (6) and H (9)) were prepared by reaction of [Pt(PCN)(R)] complexes (obtained from the corresponding chlorides) with an equivalent of RLi, as a result of the opening of the chelate ring. Alkylating agents based on other metals produce less stable products. These anionic d8 complexes are thermally stable although they bear no stabilizing pi acceptors. They were characterized by 1H, 31P[1H], 13C, and 7Li NMR spectroscopy; complex 9 was also characterized by single crystal X-ray crystallography, showing that the Li+ ion is coordinated to the nitrogen atom of the open amine arm and to the hydride ligand (trans to the P atom) of a neighboring molecule (H--Li=2.15 A), resulting in a dimeric structure. Complexes 4 and 9 exhibit high nucleophilic reactivity, upon which the pincer complex is regenerated. Reaction of 4 with water, methyl iodide, and iodobenzene resulted in the neutral complex [Pt(PCN)(CH3)] (3) and methane, ethane, or toluene, respectively. Labeling studies indicate that the reaction proceeds by direct electrophilic attack on the metal center, rather than attack on the alkyl ligand. The anionic dihydride complex 9 reacted with water and methyl iodide to yield [Pt(PCN)(H)] (8) and H2 or methane, respectively. 相似文献
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V. A. Nikanorov S. V. Sergeev V. I. Rozenberg O. A. Reutov 《Russian Chemical Bulletin》1988,37(4):804-806
1. | The possibility was demonstrated for the base-catalyzed Knoevenagel condensation of 4-methyl-4-trichloromethyl-2,5-cyclohexadien-1-one with dimedone with the formation of 4-methyl-4-trichloromethyl-1-(4,4-dimethyl-2,6-dioxocyclohexylidene)-2,5-cyclohexadiene. |
2. | An explanation was offerred for the thermal stability and spectral characteristics of the semiquinoid trienedione obtained assuming polarization of the product molecule due to the presence of two extended (C=C)2C=C(C=O) cross-,,-conjugation chains. |
10.
A. S. Rozenberg E. I. Aleksandrova G. I. Dzhardimalieva A. N. Titkov A. D. Pomogailo 《Russian Chemical Bulletin》1993,42(10):1666-1672
The thermal decomposition of iron (III) acrylate, [Fe3O(CH2=CHCOO)6 · 3H2O]OH (FeAcr), a monomer with a complex cluster cation, has been studied at 200–370 °C. Thermal transformations of FeAcr occur
in two temperature regions. The rates of gas evolution in the low temperature region (200–300 °C) and the high temperature
region (300–370 °C) are described by first-order equations withk=4.2 · 1021exp[−59000/(RT)] s−1 andk=1.3 · 106exp[−30500/(RT)] s−1, respectively. A study of the qualitative and quantitative composition of the products of FeAcr thermolysis was carried out.
The thermal transformation of FeAcr is a complex process of dehydration, degradation, and polymerization in the solid phase
followed by decarboxylation of the metal-carboxyl groups of the polymer.
for part 33 see Ref. 1.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1743–1750, October, 1993. 相似文献