Cathodic oligomerisation of bis(diazo) compounds of the indenofluorene series. Part I. General features

Abstract

Three bis(diazo) compounds of the indenofluorene series, 11,12-bis(diazo)-11,12-dihydro-indeno[2,1-a]fluorene (1b), 10,12-bis(diazo)-10,12-dihydroindeno[2,1-b]fluorene (2b), and 6,12-bis(diazo)-6,12-dihydroindeno[1,2-b]fluorene (3b) have been prepared and decomposed by an electrochemically initiated chain process in dimethylformamide solution. The black solutions so obtained show single-line e.s.r. spectra and electronic absorption spectra extend into the near infra-red region of the spectrum. in situ electrochemical e.s.r. spectra of electrolysed solutions of (1b) and (2b) in CH₃CN are similar to spectra reported for lightly doped conjugated polymers. Chemical evidence is presented to show that the products are polyazines and the results of elemental and gel permeation chromatographic analysis suggest degrees of polymerisation in the range 2–5 for (1b) and ca. 17 for (2b) and (3b), although in the latter instances there is evidence for material of much greater molecular weight. The black solid materials isolated from the electrolysis solutions and containing supporting electrolyte (Me₄NBF₄) show specific conductivities of ca. 10^–10(1b), 10^–9(2b), and 10^–6(3b) ohm^–1 cm^–1, all increasing to 10^–4–10^–3 on exposure to gaseous SO₃.