Synthesis and fundamental properties of stable Ph ₃SnSiH ₃ and Ph ₃SnGeH ₃ hydrides: Model compounds for the design of Si-Ge-Sn photonic alloys

The compounds Ph ₃SnSiH ₃ and Ph ₃SnGeH ₃ (Ph = C ₆H ₅) have been synthesized as colorless solids containing Sn-MH ₃ (M = Si, Ge) moieties that are stable in air despite the presence of multiple and highly reactive Si-H and Ge-H bonds. These molecules are of interest since they represent potential model compounds for the design of new classes of IR semiconductors in the Si-Ge-Sn system. Their unexpected stability and high solubility also makes them a safe, convenient, and potentially useful delivery source of-SiH ₃ and-GeH ₃ ligands in molecular synthesis. The structure and composition of both compounds has been determined by chemical analysis and a range of spectroscopic methods including multinuclear NMR. Single crystal X-ray structures were determined and indicated that both compounds condense in a Z= 2 triclinic (P1̄) space group with lattice parameters (a = 9.7754(4) Å, b = 9.8008(4) Å, c = 10.4093(5) Å, α = 73.35(10)°, β = 65.39(10)°, λ = 73.18(10)°) for Ph ₃SnSiH ₃ and (a = 9.7927(2) Å, b = 9.8005(2) Å, c= 10.4224(2) Å, α = 74.01(3)°, β = 65.48(3)°, λ = 73.43(3)°) for Ph ₃SnGeH ₃. First principles density functional theory simulations are used to corroborate the molecular structures of Ph ₃SnSiH ₃ and Ph ₃SnGeH ₃, gain valuable insight into the relative stability of the two compounds, and provide correlations between the Si-Sn and Ge-Sn bonds in the molecules and those in tetrahedral Si-Ge-Sn solids.