The photolysis of a benzene solution of [Tp(Me2)IrH(2)(COE)], 1 (Tp(Me2) = hydrotris(3,5-dimethylpyrazolyl)borate, COE = Z-cyclooctene), in the presence of P(OMe)(3), gives the stable novel complex [Tp(Me2)IrH(C(6)H(5))(P(OMe)(3))], 3a. The photochemical syntheses of [Tp(Me2)IrH(2)(P(OMe)(3))], from 1 and P(OMe)(3) in diethyl ether, and [Tp(Me2)IrH(2)(CH(2)=CHCOO(t)Bu)], from 1 in tert-butyl acrylate, are also reported. The above reactions and several experiments using C(6)D(6) and P(OCD(3))(3) show that, in all cases, the primary photoproduct is the 16-electron, five-coordinate iridium(III) intermediate {Tp(Me2)IrH(2)}, 6a, produced by loss of COE from 1. The above experiments also allow the postulation of a mechanistic pathway for the formation of 3a which involves the oxidative addition of an aromatic C-H bond by 6a. Furthemore, the photochemical reaction of 1 in the presence of P(OCD(3))(3) shows that, under the reaction conditions used, oxidative addition of C-H bonds of P(OMe)(3) and of coordinated Tp(Me2)-ligands, presumably, to the intermediates 6a and {Tp(Me2)IrH(C(6)H(5))}, also occurs. Thus, coordinatively unsaturated iridium(III) species readily activate C-H bonds.

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The photochemical rearrangement of [Rh(η4‐1,5‐cod)TpMe2](TpMe2=hydrotris(3,5‐dimethylpyrazolyl)borato, 1,5‐cod=cycloocta‐1,5‐diene) to the new compound [Rh(η4‐1,3‐cod)TpMe2] (2) is described. The characterization of 2 was carried out using 1H‐, 13C‐, and 103Rh‐HMQC‐NMR spectroscopy. Photolysis of 2 is a versatile entry point into the organometallic chemistry of the {RhTpMe2} fragment as it can be used to produce a) hydrido‐carbonyl ([Rh(CO)H2TpMe2]), b) hydrido‐phenyl‐phosphite ([RhH(Ph)(P(OMe)3)TpMe2]), and c) ethoxide‐hydrido‐phosphite ([RhH(OEt)(P(OMe)3)TpMe2]) complexes.