Reactions of the heteroleptic diarylgermylenes GeAr#(Ar') (1) or GeAr# (Ar*-3,5-Pr'(2)) (2) (Ar-# = C6H3-2,6-(C6H2-2,4,6-Me-3)(2); Ar' = C6H3-2,6-(C6H3-2,6-Pr'(2))(2); Ar*-3,5-Pr'(2) = C6H-2,6-(C6H2-2,4,6-Pr'(3))(2)-3,5-Pr'(2)) with carbon monoxide at room temperature gave alpha-germyloxy ketones via double CO insertion into the Ge-Ar' carbon bond in 1 and the Ge-Ar-# bond in 2. The (ArGe)-Ge-#-OCC(O)Ar' and 3,5-Pr'Ar-2*Ge-O-CC(O)Ar-# intermediates that are formed are unstable and rearrange via the insertion of the carbon of the GeOC moiety into a methyl-aryl or isopropyl. carbon to form six-membered ring products.