Dinuclear Rhodium and Iridium Complexes with Mixed Amido/Methoxo and Amido/Hydroxo Bridges

The reactions of [{M(μ-OMe)(cod)}2] (M = Rh, Ir; cod = 1,5- cyclooctadiene) with p-tolylamine, α-naphthylamine,
and p-nitroaniline gave complexes with mixed-bridging ligands, [{M(cod)}2(μ-NHAr)(μ-OMe)]. Similarly, the related
complexes [{Rh(cod)}2(μ-NHAr)(μ-OH)] were prepared from the reactions of [{Rh(μ-OH)(cod)}2] with p-tolylamine,
α-naphthylamine, and p-nitroaniline. The reactions of [{Rh(μ-OR)(cod)}2] (R = H, Me) with o-nitroaniline gave the
mononuclear complex [Rh(o-NO2C6H4NH)(cod)]. The syntheses of the amido complexes involve a proton exchange
reaction from the amines to the methoxo or hydroxo ligands and the coordination of the amide ligand. These
reactions were found to be reversible for the dinuclear complexes. The structure of [{Rh(cod)}2(μ-NH{p-NO2C6H4})(μ-OMe)] shows two edge-shared square-planar rhodium centers folded at the edge with an anti configuration of
the bridging ligands. The complex [{Rh(cod)}2(μ-NH{α-naphthyl})(μ-OH)] cocrystallizes with [{Rh(μ-OH)(cod)}2]
and THF, forming a supramolecular aggregate supported by five hydrogen bridges in the solid state. In the
mononuclear [Rh(o-NO2C6H4NH)(cod)] complex the o-nitroamido ligand chelates the rhodium center through the
amido nitrogen and an oxygen of the nitro group.