نتایج جستجو برای: strained molecules
تعداد نتایج: 198218 فیلتر نتایج به سال:
Tetrahedrane is most strained and the smallest cage compound. It attracts organic chemists because ofits unusual bonding nature and highly symmetrical structure. However, many efforts to isolate theparent tetrahedrane have been unsuccessful because of the high reactivity and very short lifetimecaused by the strain in this molecule. Modeling of molecules for determination of structuralproperties...
At RHF, MPn, and DFT levels, a procedure of geometry optimization under the restrictions of pi-orbital interactions (GOR) was developed, thus providing a conjugated molecule with the following two types of localized reference geometries: a "GL" geometry where all double bonds are localized, and n different "GE-n" geometries, in each of which only two double bonds were permitted to conjugate. In...
background: aflatoxin m1 (afm1) is a toxic compound that could be found in milk and dairy products. afm1 is the principle hydroxylated derivative of aflatoxin b1 (afb1), formed in liver and excreted into the milk in the mammary glands of both human and lactating animals that have been fed with afb1 contaminated diet. to the best of our knowledge, there is no report on stability of afm1 during p...
Ab initio calculation at HF/6-31G* level of theory for geometry optimization and MP2/6-31G*//HF/6-31G* for a single point total energy calculation are reported for the important energyminimumconformations and transition-state geometries of of cyclodeca-1,2,3-triene (1). The mostfavorable conformation of 1 is a unsymmetrical twist-chair (1-TC) structure. Degenerateinterconversion of 1-TC with it...
A novel stable donor/acceptor-supported MnI-metallasilanone 3 was synthesized. The intramolecular silanone-MnI interaction induces a highly strained three-membered cyclic structure, leading to an exceptionally high reactivity of as donor/acceptor complex silanone. Indeed, metallasilanone readily reacts with various small molecules such H2 or ethylene gas in mild conditions.
tetrahedrane is most strained and the smallest cage compound. it attracts organic chemists because ofits unusual bonding nature and highly symmetrical structure. however, many efforts to isolate theparent tetrahedrane have been unsuccessful because of the high reactivity and very short lifetimecaused by the strain in this molecule. modeling of molecules for determination of structuralproperties...
The development of new methodologies catalyzed by late transition metals involving cycloisomerizations of strained rings can open new venues for the synthesis of structurally complex molecules with interesting biological activities. Herein we summarize, from both a synthetic as well as a mechanistic point of view, the most recent developments in gold-catalyzed ring expansions.
Strain-promoted inverse electron-demand Diels-Alder cycloaddition (SPIEDAC) reactions between 1,2,4,5-tetrazines and strained dienophiles, such as bicyclononynes, are among the fastest bioorthogonal reactions. However, the synthesis of 1,2,4,5-tetrazines is complex and can involve volatile reagents. 1,2,4-Triazines also undergo cycloaddition reactions with acyclic and unstrained dienophiles at ...
ترانزیستورهای اثر میدانی بر روی عایق یکی از پر کاربرد ترین افزاره هاست. این فن آوری برای غلبه بر اثرات کانال کوتاه و کاهش جریان نشتی و کاهش خازنهای پارازیتی نقش مفیدی ایفا کرده است. همچنین با توجه به اهمیت کاربردهای ترانزیستورهای اثر میدانی بر روی عایق در طراحی مدارهای مجتمع rfبرای کاربردهای رادیویی و مخابراتی، ماهواره ها و سیستمهای بی سیم ، بهبود ساختار این افزاره ها مورد توجه اکید قرار گرفته ...
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