تفاصيل الوثيقة
نوع الوثيقة |
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مقال في مجلة دورية |
عنوان الوثيقة |
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An electron spin resonance, ENDOR, and TRIPLE resonance study of methyl-substituted N,N′-diphenyl-4,4′-bipyridylium dichloride radical cations An electron spin resonance, ENDOR, and TRIPLE resonance study of methyl-substituted N,N′-diphenyl-4,4′-bipyridylium dichloride radical cations |
الموضوع |
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كيمياء |
لغة الوثيقة |
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الانجليزية |
المستخلص |
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The e.s.r. and ENDOR spectra of the radical cations of N,N′-diphenyl- 4,4′-bipyridylium dichloride (DPQ), N,N′-bis-(4-methylphenyl)-4, 4′-bipyridylium dichloride (p-mDPQ), N,N′-bis-(3-methylphenyl)-4, 4′-bipyridylium dichloride (m-mDPQ), N,N′-bis-(2-methylphenyl-4, 4′-bipyridylium dichloride (o-mDPQ), and N,N′-bis-(2,4,6- trimethylphenyl)-4,4′-bipyridylium dichloride (T-mDPQ) in methanol were studied over a range of temperatures. Values for the hyperfine coupling constants are given at -40°C. It was found that the radical cation concentrations of DPQ+., p-mDPQ+., m-mDPQ+., and o-mDPQ+. decreased with decreasing temperature, this change being reversible, whilst that of T-mDPQ+. did not. We explain the reversible change with temperature in terms of a monomer-dimer equilibrium, and the absence of such an equilibrium in the case of T-mDPQ+. as due to the lack of planarity of the molecule, because of steric hindrance between the methyl groups and the pyridyl ortho-protons. The thermodynamic constants ΔG°, ΔH°, and ΔS°, obtained for the dimerisation equilibria, are reported. |
ردمد |
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0300-9580 |
اسم الدورية |
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Journal of the Chemical Society, Perkin Transactions 2 |
المجلد |
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1985 |
العدد |
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2 |
سنة النشر |
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1985 هـ
1985 م |
عدد الصفحات |
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4 |
نوع المقالة |
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مقالة علمية |
تاريخ الاضافة على الموقع |
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Monday, October 19, 2009 |
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الباحثون
Clack, D.W | Clack, D.W | باحث | دكتوراه | |
Evans, J.C. | Evans, J.C. | باحث | دكتوراه | |
عبدالله يوسف عبدالله عبيد | Abdullah Yousif Obaid | باحث | دكتوراه | aobaid@kau.edu.sa |
Rowlands, C.C. | Rowlands, C.C. | باحث | دكتوراه | |
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الرجوع إلى صفحة الأبحاث
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