Stereocontrol of Metal‐Centred Chirality in Rhodium(III) and Ruthenium(II) Complexes with N₂N'P Ligand

Rh(III) and Ru(II) complexes, [RhCl 2 ( κ 4 ‐ N 2 N'P ‐ L )][SbF 6 ] ( 1 ) and [RuCl 2 ( κ 4 ‐ N 2 N'P ‐ L )] ( 2 ), were synthesised using the tetradentate ligand L ( L = N , N ‐bis[(pyridin‐2‐yl)methyl]‐[2‐(diphenylphosphino)phenyl]methanamine). In each case only one diastereomer is detected, featuring cis ‐disposed pyridine groups. The chloride ligand trans to pyridine can be selectively abstracted by AgSbF 6 , with the ruthenium complex ( 2 ) reacting more readily at room temperature compared to the rhodium complex ( 1 ) which requires elevated temperatures. Rhodium complexes avoid the second chloride abstraction, whereas ruthenium complexes can form the chiral bisacetonitrile complex [Ru( κ 4 ‐ N 2 N'P ‐ L )(NCMe) 2 ][SbF 6 ] 2 ( 5 ) upon corresponding treatment with AgSbF 6 . The complex [RhCl 2 ( κ 4 ‐ N 2 N'P ‐ L )][SbF 6 ] ( 1 ) has also been used to synthesise polymetallic species, such as the tetrametallic complex [{RhCl 2 ( κ 4 ‐N 2 N'P ‐ L )} 2 (μ‐Ag) 2 ][SbF 6 ] 4 ( 6 ) which was formed with complete diastereoselectivity and chiral molecular self‐recognition. In addition, a stable bimetallic mixed‐valence complex [{Rh( κ 4 ‐N 2 N'P ‐ L )}{Rh(COD)}(μ‐Cl) 2 ][SbF 6 ] 2 ( 7 ) (COD=cyclooctadiene) was synthesised. These results highlight the significant differences in chloride lability between Rh 3+ and Ru 2+ complexes and demonstrate the potential for complexes to act as catalyst precursors and ligands in further chemistry applications.