Reduction of iridium in solution

Iridium(IV) in solution may be reduced to metal via the intermediate Ir(I). Reduction of Ir(III) has not been detected. The current efficiency for metal deposition is low because: (1) The (IV)-(I) reduction is competing with the (IV) to (III) reduction, and hydrogen evolution in aqueous solution. (2) Ir(I) is very easily oxidised to (III), even by hydrogen. (3) Some iridium salts are not stable in the (IV) state (e.g. triaquotrichloroiridate in molar chloride).