Step-Growth Coordination Polymerization of 5-Hydroxymethyl Furfural with Dihydrosilanes: Synergistic Catalysis Using Heteroscopionate Zinc Hydride and B(C6 F5 )3.

The utilization of 5-hydroxymethyl furfural (HMF) as a renewable feedstock for polymer synthesis has not yet been achieved as it is structurally asymmetric and contains three active functional groups. Reported here is the unprecedented step-growth copolymerization of HMF and dihydrosilanes, through a coordination mechanism, to afford linear poly(silyl ether)s in the presence of B(C6 F5 )3 and the heteroscorpionate zinc hydride complex LZnH [L=(Me Pz)2 CP(Ph)2 NPh, Me Pz=3,5-dimethylpyrazolyl]. The adduct B(C6 F5 )3 ⋅⋅⋅H⋅⋅⋅Zn, confirmed by NMR spectroscopy and DFT calculations, plays a key role in the synergistic catalysis, where B(C6 F5 )3 activates ZnH and stabilizes the Zn+ active species, and the sterically bulky ZnH effectively inhibits (C6 F5 )3 B from reacting with dihydrosilane to form (C6 F5 )3 B-H-Si, which facilely initiates ring opening of furan. The mechanism was studied by DFT simulations.