Cationic and Formally Zwitterionic Rhodium(I) and Iridium(I) Derivatives of a P,N-Substituted Indene: A Comparative Synthetic, Structural, and Catalytic Investigation

A family of neutral, cationic, and formally zwitterionic Rh(I) and Ir(I) complexes featuring 1-PiPr2-2-NMe2-indene (3a), 3-PiPr2-2-NMe2-indene (3b), or 3-PiPr2-2-NMe2-indenide (3c) ligands have been prepared and structurally characterized. Whereas treatment of 3a with 0.5 equiv of [(COD)RhCl]2 afforded (COD)RhCl(κ1-P,N-3a) (4a) in 96% isolated yield, [(COD)M(κ2-P,N-3a)]+X- ([5a]+PF6-, M = Rh; [6a]+SO3CF3-, M = Ir) complexes were obtained in 14% and 41% isolated yield from 3a and the appropriate in-situ-prepared [(COD)M(THF)2]+X- precursor. The isomeric complexes [(COD)M(κ2-P,N-3b)]+X- ([5b]+X-, M = Rh; [6b]+X-, M = Ir) were prepared using a similar protocol employing NEt3, with isolated yields ranging from 37% to 94% depending on the identity of M and X. The zwitterionic complexes (COD)M(κ2-P,N-3c) (5c, M = Rh; 6c, M = Ir) were prepared in 89% and 93% isolated yield, either upon treatment of [5b]+X- or [6b]+X- with NaN(SiMe3)2 or via addition of 0.5 equiv of [(COD)MCl]2 to [3c]Li. The Rh(I) complexes (CO)...