Germane photochemistry. Photolysis of gas mixtures of planetary interest

Photolysis of germane (GeH ₄) in the presence of acetylene (C ₂H ₂), propyne (C ₃H ₄) or phosphine (PH ₃) with a 185 nm mercury lamp has been studied. The volatile products formed in these reactions are characterized by ¹H, ³¹P and ¹³C NMR. Vinylgermanes are the first reaction products formed in the photolysis of GeH ₄ with alkynes. A reaction pathway is proposed. The initial step is the dissociation of germane 1 to hydrogen and GeH ₃ radicals. Addition of the germyl radical on alkyne is proposed as the next step. Vinylgermanes are then formed by radical combination. Photolysis of ethenylgermane 2 gives diethenylgermane 3 in the presence of acetylene and digermaethane 4 in the presence of GeH ₄. The application of these findings to Jovian and Saturn atmospheric chemistry is discussed.