Rh NMR studies of organometallic rhodium(I) derivatives

Abstract

The correlation of 6Rh with ligand properties has been extended to a wider range of complexes by using the 'influence parameters' defined previously (10 points, R=0.947). The sensitivity of 6Rh to steric factors is also proved.

Silsesquioxanes as models of silica supported catalyst I. [3-(Diphenylphosphino)propyl]-hepta[propyl]-[octasilsesquioxane] and [3-mercapto-propyl]-hepta[propyl]-[octasilsesquioxane] as ligands for transition-metal ions

“…However, no uniform products could be obtained by this method as it was not in all [Rh(CO) 2 Cl] 2 molecules that both "-Cl bridges were exchanged. A complete reaction was observed by Bolton et al 26 and Kalck et al 27 22 The existence of two isomers can be explained by a slow inversion around the sulfur atoms of the Rh 2 S 2 ring. 28 Of the three possible configurations of the ring, the one with the two siloxane cages on the sulfur in the axial position can be excluded from consideration by the size of the cage.…”

Rhodium(I) Complexes with Hemilabile Phosphines: Rational Design for Efficient Oxidative Amination Catalysts

“…[Rh(cod){Ph 2 P(CH 2 ) 2 SMe}] + ( 13 ), which contained the (2‐(thiomethyl)ethyl)diphenylphosphine ligand, showed featureless signals for the CH and CH 2 protons in CD 2 Cl 2 , even at −80 °C, which could be an indication of an equilibrium that involved different species with κ 2 ‐P,S‐ and κ‐P‐coordinated ligands, or even polynuclear species. The 31 P{ 1 H} NMR spectra featured a doublet with J (P,Rh)≈150 Hz, which was in the typical range for rhodium(I) compounds 28. This resonance was in the range δ =22–18 ppm for the complexes that contained six‐membered‐ringed metallocycles ( n =3) and was shifted to lower fields, δ =60–40 ppm, in the complexes that contained five‐membered‐ringed metallocycles ( n =2).…”

Silsesquioxanes as models of silica supported catalyst I. [3‐(Diphenylphosphino)propyl]‐hepta[propyl]‐[octasilsesquioxane] and [3‐mercapto‐propyl]‐hepta[propyl]‐[octasilsesquioxane] as ligands for transition‐metal ions

“…The 1 J(Rh,P) coupling of 150.4 Hz of the resonance at = 25.4 ppm in the 31 P spectrum is in accordance with a literature value of 149 Hz for a comparable compound. 22 The same arguments apply to the 13…”

“…The chemical shifts and the carbon-rhodium couplings are as expected from literature data. 22 The existence of two isomers can be explained by a slow inversion around the sulfur atoms of the Rh 2 S 2 ring. 28 Of the three possible configurations of the ring, the one with the two siloxane cages on the sulfur in the axial position can be excluded from consideration by the size of the cage.…”