1 : 2 polycondensation of 3,3 ',4,4 '-biphenyltetramine and l,l '-ferrocenedimethanol catalyzed by [RuC1(2)(PPh3)(3)] to give polybenzimidazole containing ferrocenylene groups

The 1 : 2 polycondensation of 3,3',4,4'-biphenyltetramine and 1,1'-ferrocen edimethanol catalyzed by [RuCl2(PPh3)(3)] gives ferrocenylene-containing po lybenzimidazole 1, (Im-Fc-CH2-O-CH2-Fc)(n) (Im = [5,5'-bi(benzimidazole)]-2 ,2'-diyl, Fe = 1,1'-ferrocenediyl). The reaction involves 1:2 condensation off 3,3',4,4'-biphenyltetramine and 1,1'-ferrocenedimethanol to make two im idazole rings and subsequent intermolecular dehydrating coupling of two CH2 OH groups to form the CH2-O-CH2 linkage. Polymer 1 is soluble in DMF and DM SO and has molecular weights, M-n = 2.1 x 10(4) and M-w = 4.5 x 10(4), dete rmined by GPC (polystyrene standards). Extremely broad H-1 NMR signals and results of SQUID measurements showing paramagnetism of 1 suggest the presen ce of Fe(III) centers in the polymer. The content of Fe(III) is estimated a s approximately 20% based on the Mossbauer spectrum of 1. An equimolar reac tion of 1,2-diaminobenzene and 1,1'-ferrocenedimethanol in the presence of the Ru(TI) catalyst gives bis[1'-(benzimidazol-2-yl)ferrocen-1-ylmethyl] et her. The model compound shows reversible oxidation and reduction peaks assi gned to the Fe(II)/Fe(III) redox, whereas the Polymer 1 undergoes oxidation and subsequent irreversible deprotonation to give the electrochemically in ert polymer.