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Volumn 121, Issue 30, 1999, Pages 7011-7019

π- and σ-diazo radical cations: Electronic and molecular structure of a chemical chameleon

Author keywords

[No Author keywords available]

Indexed keywords

5 DIAZO 10,11 DIHYDRO 5H DIBENZO[A,D]CYCLOHEPTENE; 9 DIAZO 9,10 DIHYDRO 10,10 DIMETHYLANTHRACENE; DIAZONIUM COMPOUND; DIPHENYLDIAZOMETHANE; UNCLASSIFIED DRUG;

EID: 0033523272     PISSN: 00027863     EISSN: None     Source Type: Journal    
DOI: 10.1021/ja9903328     Document Type: Article
Times cited : (9)

References (56)
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    • The configurational description in the last column of Table 1 is given in terms of a CASSCF wave function including only the MOs depicted in Figure 3. This procedure is justified because, with the larger active spaces which are necessary to arrive at satisfactory CASPT2 wave functions and energies, big rotations among the MOs of the same symmetries lead to a loss of the transparency obtained at the (9,11)CASSCF level.
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    • The phases of the MOs can be chosen such that the directions of the transition moments are reverted. However, this alternative entails a change in the sign of the CI coefficients, so that the final result remains the same.
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    • Excitations from doubly occupied into virtual MOs of radicals cannot be described correctly by single configurations, of which three must be combined into so-called configuration state functions. As a consequence, the contributions of the 26a → 26b and the 26a → 26b excitations add up to more than 100% in the final-state wave functions.
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    • A table containing all measured and calculated hyperfine-coupling constants is available in the Supporting Information.
  • 43
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    • H| value has a sign opposite to the two larger ones; the former is undoubtedly positive, while the latter have a negative sign.
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    • note
    • .+ observed by us with Freon matrices are available in the Supporting Information.
  • 47
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    • note
    • .+, are available in the Supporting Information.
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    • note
    • .+, are compiled in the table which is contained in the Supporting Information.
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  • 50
    • 13044252819 scopus 로고    scopus 로고
    • note
    • Upon projection of the quartet components, the (P)UMP2/STO-3G σ/π-gap increases to nearly 80 kcal/mol! Such problems can be avoided by going to the spin-restricted MP2 method (RMP2). With the 6-31G* basis set, this method predicts a σ/π-gap of nearly 40 kcal/mol which also turns out to be significantly too high (see below). Thus, the MP2 method may be inherently inadequate for estimating the energy difference between the delocalized π-radical and the localized σ-radical state.
  • 51
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    • note
    • 2 group is bent towards the phenyl ring), the latter was disregarded in the subsequent calculations.
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    • note
    • 50 was calculated. This energy was found to be 33 kcal/mol (32.2 kcal/mol after correcting for the basis set superposition error), hence B3LYP is expected not to underestimate the binding energies of chloronium cations.
  • 55
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    • note
    • As the allylic π-MO is essentially nonbonding, the geometry of diazomethane undergoes only minor changes on ionization (with B3LYP/ 6-31G*, the C-N bond lengthens by 4 pm, the N-N bond shortens by 2 pm).
  • 56
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    • note
    • σ-AO of the terminal nitrogen atom.


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.