Dodecacarbonyltriruthenium reacts with refluxing di-n-butyl ether to produce α-H4Ru4(CO)12, Ru6C(CO)17, and a new isomer of the tetranuclear dihydride (α-)H2Ru4(CO)13. Bands appearing at 1248 ± 2 cm.–1 in the i.r. spectrum of α- H4Ru4(CO)12 and at 902 ± cm.–1 in the spectrum of α-D4Ru4(CO)12 are assigned to the vibrations ν(Ru–H–Ru) and ν(Ru–D–Ru) respectively. I.r., n.m.r., and mass spectroscopic data indicate that two forms (α and β) of H2Ru4(CO)13 exist. The reaction of Ru6C(CO)17 with donor ligands, L (L = Ph3P, (C6H4F)3P, or Ph3As) have been examined and the monosubstituted complexes Ru6C(CO)16·L have been characterised.