Frustrated Lewis Pair Chelation as a Vehicle for Low-Temperature Semiconductor Element and Polymer Deposition

The stabilization of silicon(II) and germanium(II) dihydrides by an intramolecular Frustrated Lewis Pair (FLP) ligand, PB, ⁱ Pr₂ P(C₆ H₄ )BCy₂ (Cy=cyclohexyl) is reported. The resulting hydride complexes [PB{SiH₂ }] and [PB{GeH₂ }] are indefinitely stable at room temperature, yet can deposit films of silicon and germanium, respectively, upon mild thermolysis in solution. Hallmarks of this work include: 1) the ability to recycle the FLP phosphine-borane ligand (PB) after element deposition, and 2) the single-source precursor [PB{SiH₂ }] deposits Si films at a record low temperature from solution (110 °C). The dialkylsilicon(II) adduct [PB{SiMe₂ }] was also prepared, and shown to release poly(dimethylsilane) [SiMe₂ ]_n upon heating. Overall, this study introduces a "closed loop" deposition strategy for semiconductors that steers materials science away from the use of harsh reagents or high temperatures.