Redox-Transmetalation Reactions: Easy Access to Homo- and Heterodimetallic d 8 ,d 10 Complexes.

The ability of the imine PyCH═N-CH 2 Py (Py = 2-pyridyl, bpi) to behave as a heteroditopic ligand, which is suitable for creating two separate compartments to host metals in different oxidation states, has been developed by studying the reactions of the mixed-valence complexes [(cod)M -Ι (μ-bpi)M Ι (cod)] (M = Rh, Ir) with [M'(Cl) 2 (PPh 3 ) 2 ] (M' = Pd, Ni). The results depend on the molar ratio of the reagents used (1:1 or 1:2) to give the heterometallic complexes {d 10 -M',d 8 -M}-[(PPh 3 )(Cl)M' 0 (μ-bpi)M Ι (cod)] (Pd,Rh, 4 ; Pd,Ir, 5 ; Ni,Rh, 8 ; Ni,Ir, 9 ) and the two-electron mixed-valent compounds [(PPh 3 )(Cl)M' 0 (μ-bpi)M' ΙΙ (Cl)] (M' = Ni, 10 ; Pd, 11 ), respectively. A redox process occurs in the replacement of the low-valent [(cod)M -I ] fragment, whereas the exchange of the [(cod)M I ] fragment is redox-neutral. The metal with a d 8 configuration in the products exhibits a square-planar geometry coordinated to two (Rh/Ir) or three (Ni/Pd) nitrogen atoms of the bridging bpi ligand. Conversely, the metal with a d 10 configuration adopts trigonal-planar geometries, π-bonded to the imine C═N bond. The isolated complexes 4 / 5 and 10/11 , along with the hypothetical heterometallic Pd,Ni compound ( 12 ), were studied by DFT methods. Additionally, the T-shaped moiety 'M' ΙΙ (PPh 3 )(Cl)(η 1 -CH-N(bpi))', stabilized by a secondary γ-agostic interaction, and the 'M' II (Cl)(κ 3 N -bpi)' fragment was found to be accessible redoxomers of complexes 10 and 11 by DFT calculations.