The Use of Ni(cod)(dq) (COD: 1,5-Cyclooctadiene; DQ: Duroquinone) for the Dehalogenative Coupling Polycondensation to π-Conjugated Polyarylenes

Ni(cod)(dq) (COD: 1,5-cyclooctadiene; DQ: duroquinone) with an appropriate bipyridine ligand is available for the dehalogenative polycondensation of dihaloarenes to afford pi-conjugated polymers. The reaction of 2,7-dibromo-9,9-di(n-hexylfluorene) with a nickel complex composed of Ni(cod)(dq) and 4,4 '-di-tert-butyl-2,2 '-bipyridine in DMF/toluene (1:4) proceeded at 120 degrees C for 72 h. Polyfluorene was obtained in 81% yield with M n = 13,000 (M w/M n = 2.0). Ni(cod)(dq) was found to be stored under an ambient atmosphere at room temperature, the use of which after several months vs a freshly opened nickel complex resulted to afford the corresponding polymer in a comparable yield and molecular weight. Other dihaloarenes such as fluorene with different alkyl chain structures, 1,4- and 1,3-dihalobenzenes, 5,5 '-dibromo-2,2 '-bithiophene, and 2,6-dibromo-cyclopentadithiophene, also underwent dehalogenative polymerization to afford the corresponding conjugated polymers in excellent yields with an appropriate degree of polymerization.