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 PEt3, PCy3, 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 PCy3 or P(o-tol)(3) exhibited catalytic activity and realized the catalyst-transfer polycondensation at 75 degrees C and room temperature, respectively, while the polymerization using Pd(II) catalyst ligated by PEt3 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. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015, 53, 1457-146