Bridged macrocyclic transition metal complexes, a new type of semiconducting materials

Bridged quasi–one-dimensional macrocyclic transition metal complexes [MacM(L)]_nusing phthalocyanine (Pc), tetrabenzoporphyrine (TBP), 1,2- and 2,3-naphthalocyanines (1,2-Nc; 2,3-Nc) as macrocycles (Mac) with M = e.g., Fe, Ru, Co and L = e.g., pyrazine (pyz), 1,4-diisocyanobenzene (dib), tetrazine (tz) exhibit interesting electrical properties. Regardless of the size of the bridging ligand after either chemical or electrochemical doping stable semiconducting compounds [MacM(L)X_y]_n(X = e.g., I₂BF₄⁻, ClO₄⁻…) are formed. For the first time the complete characterization of soluble oligomers [MacM(L)]_n(Mac =t-Bu₄Pc, M = Ru, L = dib, me₄dib) by¹H-NMR spectroscopy is reported. Some of these shish kebab complexes, e.g., [PcM(tz)]_n, (M = Fe, Ru) or [MacMCN]_n; (Mac = Pc, TBP; M = Co, Fe) exhibit good semiconducting properties without additional external doping. Whether or not these compounds are intrinsic semiconductors will be discussed. The synthesis of oligomeric bridged mixed valence compounds [PcM(III)LPcM(II)L]_n, (M = e.g., Fe) is another target of our work. We report here on first results of these oligomers.