The treatment of dipropargyl ether with Co 2(CO) 8 in hexane at room temperature gave a new cluster [O(CH 2C 2H-μ) 2][Co 2(CO) 6] 2 1, which reacts with the cyclopentadienyl tricarbonyl molybdenum anion [Mo(C 5H 5)(CO) 3] − to form the hetero-tetranuclear clusters [O(CH 2C 2H-μ) 2][Co 2(CO) 6][CoMo(C 5H 5)(CO) 5] 2 and [O(CH 2C 2H-μ) 2][CoMo(C 5H 5)(CO) 5] 2 3, respectively. The reaction of Mo 2(C 5H 4R) 2(CO) 4 (RH, COOCH 2CH 3) with dipropargyl ether gave the homo-dinuclear clusters [HC 2CH 2OCH 2C 2H-μ][Mo 2(C 5H 4R) 2(CO) 4] (RH 4, COOCH 2CH 3 5) and homo-tetranuclear clusters [O(CH 2C 2H-μ) 2][Mo 2(C 5H 4R) 2(CO) 4] 2 (RH 6, COOCH 2CH 3 7), respectively. The clusters 4 and 5 reacted with Co 2(CO) 8 to produce the novel tetranuclear clusters [O(CH 2C 2H-μ) 2][Co 2(CO) 6][Mo 2(C 5H 4R) 2(CO) 4] (RH 8, COOCH 2CH 3 9). All clusters were characterized by C/H analyses and IR and 1H-NMR spectroscopy and the crystal structures of 1 and 6 · 1/2CH 2 Cl 2 were determined. Crystals of cluster 1 are monoclinic with space group P2 1/ c, a=18.149(2), b=7.0111(7), c=20.807(2) Å, β=115.318(7)°, V=2403.7(5) Å 3, Z=4 and R=0.030, R w =0.031. Crystals of cluster 6 · 1/2CH 2 Cl 2 are triclinic with space group P 1 , a=7.92(3), b=13.360(3), c=17.208(4) Å, α=109.15(1), β=92.07(2), γ=93.34(2)°, V=1714.3(9) Å 3, Z=2 and R=0.040, R w =0.049.