Investigation of Suzuki–Miyaura catalyst-transfer polycondensation of AB-type fluorene monomer using coordination-saturated aryl Pd(II) halide complexes as initiators
Novel triarylamine-based coordination-saturated aryl Pd(II) halide complexes ligated by PEt 3 , PCy 3 , and P( o -tol) 3 were successfully synthesized by direct oxidative addition of aryl halide to the corresponding Pd(0) precursors. Suzuki–Miyaura coupling polymerization of 2-(7-halide-9,9-dioctylfluoren-2-yl)−1,3,2-dioxaborinane with these Pd(II) complexes as initiators was investigated for the synthesis of poly(fluorene)s with triarylamine end group. Pd(II) complexes with PCy 3 or P( o -tol) 3 exhibited catalytic activity and realized the catalyst-transfer polycondensation at 75 °C and room temperature, respectively, while the polymerization using Pd(II) catalyst ligated by PEt 3 did not proceed, which indicated that the bulky phosphine ligands could facilitate the reductive elimination and further promote the polymerization. In addition, the dimeric Pd(II) complex with P( o -tol) 3 can convert into monomeric Pd(II) intermediate with an open coordination site, which had a higher activity. The end groups of the afforded polyfluorene were analyzed by matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, in which the Ar/H end groups are indicative of the catalyst-transfer polymerization. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53 , 1457–1463
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