Magnetic Properties of Mesonaphthodianthrene

Abstract

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.

Calculation of the ground state electronic structures and electronic spectra of di- and trisulfide radical anions by the scattered wave-SCF-X.alpha. method

“…In both cases the angle formed by the three sulfur atoms was set at HO0. [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] Coordinates, a parameters, and sphere radii are summarized in Table I. Symmetry (C2y) was employed to factor the secular matrix into ai, a2, bj, and b2 blocks.…”

Effect of Ambient Oxygen on the Semiconductivities of Evaporated Films of Mesonaphthodianthrene and Mesonaphthodianthrone

“…Recently Matsunaga found that a sharp absorption peak appeared in the electron spin resonance spectrum of mesonaphthodiantlirene powder when it was exposed to air (6). This suggests that some ltind of electron transfer is taking place between the hydrocarbon crystal and oxygen molecules adsorbed on the surface.…”