S-8-mediated cyclotrimerization of 4,5-dihydrobenz[l]acephenanthrylene: trinaphthodecacyclene (C60H30) isomers and their propensity towards cyclodehydrogenation

It is shown using (high-resolution) mass spectrometry that treatment of 4,5-dihydrobenz[l]acephenanthrylene (2, c20h14) and s8 in the melt gives the insoluble 532 a.m.u. (c40h20s) and 750 a.m.u. (c60h30) bisbenz[l]acephenanthrothiophenes (4a–c) and, trinaphtho[2,1-b,2,1-m,2,1-x]- (3a) and trinaphtho[2,1-b,2,1-m,1,2-a']decacyclene (3b), respectively (estimated ratio 4a–c/3a–b 20:1). Whereas 3a fits the `c60 schlegel diagram' and might be converted into c60 (720 a.m.u.) after full cyclodehydrogenation, 3b can only give a curved c60h12/c60h10 (732:730 a.m.u.). Maldi time-of-flight mass spectrometry shows that cyclodehydrogenations of 3a–b down to 732:730 a.m.u. Occur; no evidence for c60 formation was found. This is attributed to the preferred formation of 3b, the lack of cyclodehydrogenation selectivity and the occurrence of c2 extrusions.