Azidophosphonamido Rhodium(I) and Iridium(I) Complexes: Synthesis, Properties, and Linkage Isomerism

A series of azidophosphonamido rhodium(I) and iridium(I) complexes ([ i Pr 2 P(N 3 R)NR]ML x ; M = Rh, Ir; R = 1‐adamantyl (Ad), mesityl (Mes); L = cyclooctadiene (COD), x = 1, cyclooctene (COE), x = 2, CO, x = 2) were prepared, and their stability and reactivity investigated. In the 1,5‐cyclooctadiene (L = COD) complexes, the azidophosphonamido ligands coordinate in a κ 2 ‐N , N α fashion, in which the PN 3 moiety adopts a transoid conformation. Irradiation (λ = 365 nm) resulted in linkage isomerization to the κ 2 ‐N , N β isomers without loss of N 2 . Substitution of the COD co‐ligands with CO in the κ 2 ‐N , N α complexes occurred with retention of the transoid conformation in the solid state. Meanwhile, in the analogous bis(cyclooctene)rhodium(I) complex, [κ 2 ‐ N,N α ‐ i Pr 2 P(N 3 Mes)(NMes)]Rh(COE) 2 , the κ 2 ‐N , N α ‐coordinated azidophosphonamido ligand exhibited a cisoid conformation, the first example of a stable cisoid phosphazide in the coordination sphere of a group 9 transition metal. Unlike the COD complexes, irradiation of this species resulted in N 2 extrusion, yielding an iminophosphonamide, [κ 2 ‐ N,N ‐ i Pr 2 P(NMes) 2 ]Rh(COE) 2 . These complexes have been characterized by multinuclear NMR spectroscopy and single‐crystal X‐ray diffraction studies.