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Photooxidations of the evaporated films of rubrene, naphthacene, and pentacene were investigated by means of X-ray photoelectron spectroscopy. A rubrene film was found to be photooxidized far more easily than a naphthacene film although the molecules of rubrene and naphthacene in solution are known to be almost equally reactive for photooxidation. Although pentacene is photooxidized very easily in solution, the oxidation rate of a pentacene film was little enhanced by the light irradiation. Discussion is given on these behaviors of the evaporated films by considering the molecular packing in the solid state and the mechanism of photooxidation.

The crystal structure of the triclinic form of lead phthalocyanine has been determined. The crystal data are: C32HI6NsPb, M r = 719.7, Pi, a = 13.123 (7) The final R value is 0.059 for 7683 reflections. Two independent molecular columns exist in this crystal, but they have almost equivalent structures. The molecules are considerably distorted from C4v symmetry. The central Pb atom significantly deviates from the convex side of the phthalocyanine skeleton, and this deviation is larger than that in the monoclinic form of lead phthalocyanine. Molecules are stacked along the a axis and oriented so that their convex sides alternate. They are considerably inclined with respect to the stacking axis.

We isolated a new (second) isomer of Ca@C72. As a result of this discovery, it was confirmed that at least one of the two Ca@C72 isomers has a C72 cage that does not satisfy the so-called isolated pentagon rule (IPR), because C72 has only one IPR cage structure.

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The adsorption of oxygen, under U.V. irradiation, on the surface of MgO outgassed at 1123 K has been studied at 77 K by temperature-programmed desorption and e.s.r. spectroscopy. During adsorption ozonide and superoxide ions were formed in equal amounts. The formation of these oxygen species is explained by the reaction of oxygen molecules with a short-lived exciton produced by the absorption of a photon at a surface 0,species in a very low coordination state. Thermal decomposition of the oxygen species adsorbed at 77 K has also been studied under a dynamic vacuum. It proceeds in four steps: (i) 0; is transformed into 0.-and 0, between 77 and 300 K; (ii) 0is changed into 0;-between 77 and 473 K; (iii) 0; is also transformed into Og-, with the evolution of 0, between 300 and 673 K; (iv) finally 0;is changed into 02and 0, between 673 and 1123 K. This mechanism is also consistent with energy considerations. The formation and thermal decomposition of superoxide ions proceeds similarly both on surfaces subjected to U.V. irradiation and on surfaces containing thermally preadsorbed hydrogen.

The C–H bond of methane is easily activated on the MgO surface even below room temperature. Active sites consist of intrinsic ion pairs, O3C2−–Mg3C2+ and O4C2+, of MgO in low coordination states on which a methane molecule adsorbs in heterolytically dissociated form.

Enantiomerically pure, stable 4‐(methoxycarbonyl)phenyl selenoxide (‐)‐(VII) is isolated by fractional recrystallization of diastereoisomeric 4‐((‐)menthyloxycarbonyl)phenyl selenoxide (V) followed by removal of the chiral source.