Inhibiting σ → π Isomerization of Aryloxide Ligands in Late Transition-Metal Complexes

• Published in: Organometallics 2005-01, Vol.24 (1), p.103-109
• Main Authors: Snelgrove, Jennifer L, Conrad, Jay C, Eelman, Melanie D, Moriarty, Maeve M, Yap, Glenn P. A, Fogg, Deryn E
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om049394j

The room-temperature reaction of thallium perfluorophenoxide with RuHCl(PPh3)3 (4a) yields RuH(σ-OC6X5)(PPh3)3 (X = F, 5 F ), the structure of which was confirmed by spectroscopic, microanalytical, and X-ray analysis. The analogous phenoxide complex (X = H, 5 H ) is known to be unstable toward σ → π isomerization, and reaction of phenoxide ion with 4a affords RuH(η5-C6H5O)(PPh3)2 (6a). We conclude that the driving force for isomerization in 5 F is minimized by the electron deficiency of the perfluorophenoxide ring. In contrast, incorporation of the aryloxide entity within a chelating framework proves insufficient to inhibit isomerization. Thus, reaction of 4a or RuCl2(PPh3)3 (4b) with the sodium salt of 2‘-(diphenylphosphino)-1,1‘-binaphthyl-2-ol (NaO-MOP) yields RuX(O-MOP)(PPh3) (7a, X = H; 7b, X = Cl). Detailed 1- and 2-D NMR analysis of 7b provides unequivocal evidence that the O-MOP ligand is bound to Ru in a σ fashion through phosphorus and in a π fashion via the aryloxide ring. The crystal structure of 5F ·THF is reported.