Two iridanonaborane compounds, 4-carbonyl-5,6:8,9-bis-muH-4-hydrido-4-bis(t
rimethylphosphine)-4-irida-arachno-nona- borane(12), [IrH(B8H12)(C3H9P)(2)(
CO)], (Ia), and 2-carbonyl-2,5:6,9:8,9-tri-muH-4-chloro-2-bis(trimethylphos
phine)-2-irida- nido-nonaborane(11), [Ir(B8H10Cl)(C3H9P)(2)(CO)], (II), are
described. Compound (II) shows evidence of effective chlorine-substituent
migration during its formation.