Oxygen incorporation a to the triple bond occurs by reacting a mixture of CO~(CO)~ and Fe (CO), or HFeCo3 (C0) 12 with 3-hexyne: CO~(C~)~ E~ C~ CHOHCH~ and CO~(C~)~ E~ C~ COCH~ are obtained. Other products of the reactions are the two novel mixed-metal derivatives Fe@(CO) 9C2Et2 and F & o (C~)~ E~ C~ CHCH~; the latter is obtained also by dehydroxylation of CO~(C~)~ E~ C~ CHOHCH~ with Fe (CO) 5. The structure of F~ CO~( ...