Bridged Macrocyclic Transition Metal Complexes, a New Type of Semiconducting Materials
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BRIDGED MACROCYCLIC TRANSITION METAL COMPLEXES, A NEW TYPE OF SEMICONDUCTING MATERIALS MICHAEL HANACK*, A- HIRSCH, A-LANGE, M. REIN, G. RENZ AND P. VERMEHREN
Institut ftir Organische Chemie, Lehrstuhl ffir Organische Chemie II der Universitdit Tiibingen, Auf der Morgenstelle 18, D-7400 Tiibingen, Federal Republic of Germany
ABSTRACT Bridged quasi onedimensional macrocyclic transition metal complexes [MacM(L)]n using phthalocyanine (Pc), tetrabenzoporphyrine (TBP), 1,2- and 2,3naphthalocyanines (1,2-; 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)Xy]n (X = e.g. I, BF 4 ", C10 4 "...) are formed. For the first time the complete characterization of a soluble oligomer [MacM(L)]n (Mac = R 4Pc, M = Ru, L = dib) by 1 H-NMR spectroscopy is reported. Some of these shish kebab complexes e.g. [PcM(tz)In, (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 3 2 compounds [PcM +LPcM +L]n (M = e.g. Fe) is another target of our work. We re-
port here about first attempts to synthesize these oligomers.
RESULTS AND DISCUSSION Bridged quasi-one dimensional macrocyclic transition metal complexes linked by linear bridging ligands L containing delocalizable ir-electrons to form stacked arrangements [MacM(L)]n have been synthesized. As macrocycles Mac phthalocyanine (Pc), tetrabenzoporphyrine (TBP), 2,3-naphthalocyanine (2,3-Nc) and 2,3-tetranaphthoporphyrine (2,3-TNP) have been used. Fe, Ru, Co, Rh and others were taken as central metals and as bridging ligands e.g. pyrazine (pyz), diisocyanobenzene (dib), and substituted diisocyanobenzenes [1]. The characterization of the bridged macrocyclic metal compounds was done by IR spectroscopy or thermogravimetric methods. NMR studies to investigate the mechanism of formation of the bridged metal complexes have also been carried out with PcM(Me 4 dib) 2 and [PcM(Me 4 dib)]n, M = Fe, Ru [2].
Mat. Res. Soc. Symp. Proc. Vol. 173. ©1990 Materials Research Society
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Soluble oligomers [MacM(L)]n, namely substituted phthalocyanine oligomers [R4 PcM(dib)]n M = Fe, Ru, R = t-bu, OR' were synthesized. For [t-bu4 PcR 4 (dib)]n the 1H-NMR spectrum in solution was measured. From a detailed analysis of the spectrum the oligomeric bridged structure was proofed and the chain length was shown to be in between 7 and 35 t-bu 4 PcRu units. M6Bbauer spectroscopy was also employed to obtain additional information about the structure of the bridged macrocyclic iron compounds. The isomer shift (6) and the quadrupol splitting (AEQ) have been measured for a variety of monomeric and polymeric phthalocyaninato-, tetranaphthoporphyrinato-, and naphthalocyan
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