The Diamagnetic Sucseptibilities and Anisotropies of the Polynuclear Aromatic Compounds

Akamatu, Hideo; Matsunaga, Yoshio

doi:10.1246/bcsj.26.364

Cited by 91 publications

(15 citation statements)

References 17 publications

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“…This method is usually preferable because, according to Lasheen [2,1], the experimental errors in x may result in some errors in the absolute values of Κ 1 and K| , but even a 10% error in x^,^s makes an almost negligible error in ΔKsemi. Fortunately, the magnetic anisotropy of the benzene ring has been investigated botl theoretically and experimentally.…”

Section: Resultsmentioning

confidence: 99%

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Anisotropy of the Diamagnetic Susceptibility in 3,5-dibromo-p-amino and 3,5-dibromo-p-hydroxybenzoic Acids

Abdel‐Kader

1992

Acta Phys. Pol. A

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The mean molar susceptibility (X M ) for the two compounds 3,5-dibromo--p-aminobenzoic acid, Br2 C6 H2 (p-ΝH2)COOΗ, and 3,5-dibromo-p-hydroxybenzoic acid, Br2C6H2(p-OH)COOH, has been determined. The principal molecular susceptibilities K || and K 1 have been evaluated. The magnetic anisotropy of each of the two compounds was obtained. From the atonic coordinates, as given by the X-ray structure analysis of Br2C6H2(p-ΝH2)COOH, the crystal susceptibilities (Χ α , Xb, and X c ) have been calculated. The magnetic properties are interpreted in the light of the crystal structure. PACS numbers: 35.20.My In troductionThe strong anisotropy of the diamagnetic susceptibility of benzenoid compounds is usually explained in terms of ring current [1][2][3][4][5][6][7][8][9]. An interesting discussion with the use of ring current concept has been given by Gomes [10].In general, the principal molecular susceptibilities (K ┴ and K||) can be evaluated from the crystal susceptibilities (X1 , X2 , and χ3) combined with the orienta [9]. On the other hand, the diamagnetic anisotropy ΔK of the molecule can be calculated from the measured value of the molar susceptibility χM according to the relation [11]: where K|| is the in-plane susceptibility wlose value can be determined from the sum of the atomic susceptibilities of the molecule as discussed by Hoarau [ΙΙ] -t i o n o f t h e m o l e c u l e i n t h e c r y s t a l . T h e d e t a i l s o f t h i s m e t h o d w a s g i v e n e l s e w h e r e

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Section: Resultsmentioning

confidence: 99%

“…The strong anisotropy of the diamagnetic susceptibility of benzenoid compounds is usually explained in terms of ring current [1][2][3][4][5][6][7][8][9]. An interesting discussion with the use of ring current concept has been given by Gomes [10].…”

Section: Introductionmentioning

confidence: 99%

Anisotropy of the Diamagnetic Susceptibility in 3,5-dibromo-p-amino and 3,5-dibromo-p-hydroxybenzoic Acids

Abdel‐Kader

1992

Acta Phys. Pol. A

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“…Here we wish to present the results of a study of mesonaphthodianthrene (I) and ~neso~laphthodianthrone (11) by the electron spin resonance method. The hydrocarbons studied are co~npounds which have anomalously small values of diamagnetic susceptibility (6). This anomaly was found to be characteristic of perylene (111) and its analogues.…”

Section: Ixtroductionmentioning

confidence: 98%

Magnetic Properties of Mesonaphthodianthrene

Matsunaga¹

1960

Can. J. Chem.

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Electron spin resonance absorption was detected in lnesonaphthodianthrene and mesonaphthodianthrone. The spectra of both of these co~npounds consist of, a t least, seven lines with a separation of 4.4 oersteds and the central line has a g-value of 2.0024f 0.0002. The growthof the central line by admission of air was observed in the case of the hydrocarbon. Some suggestions are presented as to the nature of the unpaired electrons in these compounds. The magnitude of the molar diamagnetic susceptibility of mesonaphthodianthrene, after correction for the paramagnetic contribution from the unpaired electrons, is discussed in relation to the molecular structure. IXTRODUCTIONThe appearance of unpaired electro~ls has been reported in crystals of solne highly conjugated molecules, namely metal-free phthalocyanine (1, 2), violanthrone (3, 4), violanthrene (3, 4), and binaphthoquinones (5). Here we wish to present the results of a study of mesonaphthodianthrene (I) and ~neso~laphthodianthrone (11) by the electron spin resonance method. The hydrocarbons studied are co~npounds which have anomalously small values of diamagnetic susceptibility (6). This anomaly was found to be characteristic of perylene (111) and its analogues. In the sense oi the valence-bond theory the central single bonds in perylene, violanthrone (IV), and mesonaphthodianthrene can be doubled only in the excited states. EXPERIMENTAL J/Iesonaphthodianthrone was prepared by photodehydrogenation of bianthraquinone dissolved in pyridine (7). The hydrocarbon was obtained by the zinc-dust fusion of the quinone (8). The latter was found t o be reactive towards oxygen, therefore our sample was stored in an evacuated tube after repeated sublimation in high vacuum.The electron spin resonance mas examined a t a frequency of 9 ki\/Ic/s a t room temperature, and a t 7 7 O I<. RESULTSUnlilte the spectra of the other paramagnetic polycyclic aronlatic compounds, the spectra of mesonaphthodianthrene and its quillone show solne structure and this can be modified by admissio~l of air. The spectra of these two compounds consist of a t least seven lines with a separation of 4.4 oersteds and spread over 50 oersteds as shown in Fig. 1 Can.

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“…Caractdr&tiques magndtiques 129,7;129,9;130,0;130,3;131,3;132,7;134,2 126,8;127,6;127,9 (1);127,98;128,5;129,33;132,0 145,6;147,9;148,6 (2);149,4;154,9 Chrys6ne 148,0;159,0;160,7;168,5 R6f6rences: (1) Akamatu & Matsunaga (1953); (2) Akamatu & Matsunaga (1956); (3) Akamatu & Kinoshita (1959); (4) Lasheen (1968 . Cet auteur avait fond+ ses calculs sur une anisotropie X~ -X3 = 83,4 × 10 -12 m 3 mol -~ pour le diph6nyle, pris comme substance de r6f6rence, alors que la valeur r6elle de cette anisotropie serait +gale /t 78,6 x 10 -2 m ~ mol -a (Poquet, 1963).…”

Section: Donn6es Exp6rimentalesunclassified

“…Pour les compos+s monocliniques, le syst+me (3) est d'abord r+solu en partant de la valeur th+orique (P0-Ces valeurs th+ori-ques peuvent ensuite &re ajust+es sur la base des relations (5) et (6) Akamatu & Matsunaga (1953); (d) Akamatu & Matsunaga (1956); (e) Akamatu & Kinoshita (1959); (f) Banerjee & Guha (1937); (g) Rogers (1947); (h) Lasheen (1968); (i) Krishnan & Banerjee (1935 Nous avons par ailleurs v6rifi6 que l'anisotropie dans le plan apporte une contribution significative b, la r6duction de la somme des carr6s des +carts entre les valeurs observ~es et calcul6es des SPC. Cette anisotropie est donc significativement diff6rente de z6ro.…”

Section: Ddtermination Des An•otropies Moldculaires Principalesunclassified

Anisotropies diamagnétiques moléculaires expérimentales des composés aromatiques condensés

Bossche¹,

Sobry²

1981

Acta Cryst Sect A

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For explaining diamagnetic effects observed in condensed aromatic compounds, their molecular diamagnetic anisotropies must be known. A method is proposed which, on the basis of relatively accurate structural data and of two experimental crystal anisotropies, allows the determination of molecular anisotropies in the plane and perpendicular to it. For monoclinic compounds whose magnetic tensor has no revolution symmetry, it is necessary to correct to first order the orientation of the principal magnetic axes of the crystal with respect to revolution symmetry. The proposed method is applied and discussed in the case of ten condensed aromatic compounds which crystallize in the orthorhombic and monoclinic systems. It yields, in some cases, molecular anisotropies very different from those suggested by different authors. One very simplified model produces results which fit in with the molecular anisotropies obtained as long as the arrangement of the rings is not too complex.

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The Diamagnetic Sucseptibilities and Anisotropies of the Polynuclear Aromatic Compounds

Cited by 91 publications

References 17 publications

Anisotropy of the Diamagnetic Susceptibility in 3,5-dibromo-p-amino and 3,5-dibromo-p-hydroxybenzoic Acids

Anisotropy of the Diamagnetic Susceptibility in 3,5-dibromo-p-amino and 3,5-dibromo-p-hydroxybenzoic Acids

Magnetic Properties of Mesonaphthodianthrene

Anisotropies diamagnétiques moléculaires expérimentales des composés aromatiques condensés

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