Synthesis of naphthalyne-Co2(CO)6 complexes, the first example of the aryne-Co2(CO)6 complex, was achieved via cyclization of acyclic alkyne-Co2(CO)6 complex precursors containing an allylsilane and an aldehyde moiety followed by dehydration. Unique reactivities of the complexes toward oxygen to give carboxylic acid derivatives and toward alkynes to give cyclopentadienone derivatives were also disclosed