PT Journal
AU Wiebe, MA
   Watson, JET
   Killeen, C
   McIndoe, JS
   Staubitz, AC
   Manners, I
TI BH3·SMe2 addition enables molar mass control via chain stabilization in phosphine–borane dehydropolymerization
SO Polymer Chemistry / Royal Society of Chemistry
JI Polym. Chem.
PY 2025
BP 1305
EP 1312
VL 16
IS 11
PU Royal Society of Chemistry (RSC)
DI 10.1039/d4py01362j
WP https://macau.uni-kiel.de/receive/macau_mods_00005791
LA en
DE molar mass control; BH 3 ·SMe 2; polymerisation
SN 1759-9954
AB We report the synthesis of high molar mass polyphosphinoboranes using commercially available reagents through thermal dehydropolymerization in the presence of Lewis acids and bases. These dehydropolymerizations produce materials of higher molecular weight compared to the state-of-the-art catalyst, Cp(CO)2FeOTf ([PhPH-BH2]n (2), 5 mol% LiOTf, 2 M in 2-MeTHF, 100 °C, 24 h; Mn = 80 000 g mol−1, Đ = 1.64 cf. 5 mol% Cp(CO)2FeOTf, 2 M in toluene, 100 °C, 24 h, Mn = 40 000 g mol−1, Đ = 1.64). We propose a mechanism for the thermal dehydropolymerization of PhPH2·BH3 (1) with additives. Initially, the phosphine–borane adduct dissociates, yielding borane in situ, which acts as a (pre)catalyst for the dehydrogenation of 1. Subsequent addition polymerization occurs as described previously, but the addition of Lewis acids and Lewis bases allows for reversible complexation of both termini. Competition between temporary chain capping and termination events results in fewer termination events over time, leading to high molar mass materials. With this mechanism in mind, we were able to show that added BH3·SMe2 allows for control over the molar mass of the resulting materials. These results show that transition-metal catalysts are not needed in the thermal dehydropolymerization of PhPH2·BH3, and offer a new mechanistic insight that may unlock greater control over the dehydropolymerization of main-group substrates.
PI Cambridge
ER