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

Abstract

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