The reaction of coordinated isocyanate ligands to give new nitrido clusters is explored. The thermolysis of [ru4(NCO)(CO)13]-gives [Ru4N(CO)12]-in 78% recrystallized yield after 24 h. When the trinuclear isocyanate clusters [Ru3(NCO)(CO)10]-and [Ru3(NCO)(CO)u]-are heated with 1 equiv of Ru3(CO)12, the hexanuclear nitrido cluster [Ru6N(CO)16]-can be isolated in 82% yield. [Ru€N(CO)16]-reacts rapidly with CO at room temperature to give [Ru5N(CO)14]-in quantitative yield. A single-crystal X-ray crystallographic study of (PhCH2Et3N)[Ru5N(CO)14] [P1 space group, a = 12.123 (6) Å, b = 14.263 (5) Å, c = 10.642 (3) Å, a = 104.74 (3)°, β = 93.28 (3)°, γ = 80.25 (4)°, Z = 2] revealed a square-based pyramid of metal atoms with the nitrogen positioned slightly below the square face. Other interconversions among the nitrido clusters are also discussed. At high CO pressure, the isocyanate ligand can be reformed from the nitrido clusters.