A one‐pot, one‐step, high‐yield reaction leading to metal–metal dimacrocycles: the phthalocyanine dimer with a direct SiSi linkage

Phthalocyanine dimer with a direct Si—Si linkage: A response to a recent work

“…It was all the more jolting to read the recent paper of Kobayashi et al [11], who in all quiescence assert that they have obtained a phthalocyanine 3a with an Si-Si bond by the reaction of 5,6-dibutoxy-1,3-diiminoisoindoline with Si 2 Cl 6 , and propose this reaction to be a general one for the standard preparation of Si-Si-containing phthalocyanines on a preparative scale. We set forth here to negate their claim of having created an Si-Si bond in phthalocyanines.…”

“…The reaction conditions employed by us and Kobayashi et al [11] for the reaction of 1,3-diiminoisoindolines with Si 2 Cl 6 are very similar. The tetrabenzocorrole arising from the reduction of the first-formed silicon phthalocyanine by Si 2 Cl 6 is not stable in solution under light.…”

“…From the analytical data described by Kobayashi et al [11], it is indubitable that the compound 3c is in fact hydroxysilicon octabutoxy-a,b,g-triazatetrabenzocorrole and not the alleged phthalocyanine dimer with Si-Si bond as refuted below.…”

“…The mass peak observed by Kobayashi et al [11] at m/z 1120.8 exactly matches the molecular weight of hydroxysilicon octabutoxy-a,b,g-triazatetrabenzocorrole (C 64 H 81 N 7 O 9 Si, calculated MS 1120.5), while the observed so-called peak of M À 2Si (2295.3 -56.2) at m/z 2239.1 is just the double peak of the corrole compound (1120.5). The double molecular ionic peaks of macrocycle compounds such as porphyrins and phthalocyanines are commonly observed in most types of mass spectra, such as FAB-MS, FD-MS and LD-MS.…”

“…In summary, it is very clear that the reactions investigated by Kobayashi et al [11] also gave the corresponding triazatetrabenzocorroles and not the expected phthalocyanine dimers.…”