The preparation and properties of the unsaturated hydride IrH, (PPh,) , and of the carbonyl hydrides IrHCO(PPh,), and IrH,CO(PPh,), are reported. From these, with perchloric acid, IrH,CO(PPh,),ClO, has been obtained, which by action of carbon monoxide gives Ir(CO),(PPh,),C10,. This perchlorate with alkaline methanol forms the novel organometallic methoxycarbonyl compound Ir(C0,Me) (CO),(PPh,),. Tentative structures, deduced from infrared spectra and electric moments in solutions, are assigned to these compounds and to some of their derivatives.THE complex iridium hydrides so far described are of the types IrH,L, with L = PPh, 1 or PEt,Ph Continuing our work on complex iridium compounds with triphenylphosphine as ligand, we now report on an unsaturated hydride IrH3L, and two carbonyl hydrides: IrHCOL, and IrH,COL,; also the perchlorate of two complex cations, which can be considered substitution products of [Ir(CO),]+, as well as a novel organometallic derivative Ir(C0,Me) (CO),L,.The Unsaturated Hydride IrH3L2.-By reduction of IrHI,L, and [IrI,L,] I, with sodium hydroborate or lithium tetrahydroaluminate, we obtained a stable compound (I), almost and IrH(CO)L, with L = PPh,.,