68811-63-2Relevant academic research and scientific papers
THE MECHANISM OF ASYMMETRIC HOMOGENEOUS HYDROGENATION. SOLVENT COMPLEXES AND DIHYDRIDES FROM RHODIUM DIPHOSPHINE PRECURSORS
Brown, John M.,Chaloner, Penny A.,Kent, Alexander G.,Murrer, Barry A.,Nicholson, Philip N.,et al.
, p. 263 - 276 (2007/10/02)
Bicyclohepta-2,5-diene and cycloocta-1,5 diene(biphosphine)rhodium tetrafluoroborates react with hydrogen at 1 atmosphere in methanol or other polar solvents.The initial product may be either a solvated dihydride or a solvate; depending on phosphine structure the equilibrium between these two species varies widely.Dihydrides are normally the stable product when the ligand is a monophosphine although (o-methoxyphenyl)methylphenylphosphine is an exception. cis-Chelating biphosphines normally form solvate complexes with no affinity for hydrogen.R-Phenyl bis-diphenylphosphinoethane falls into this category, but the 31P NMR spectra of its complexes demonstrate an equilibrium between monomeric and dimeric species, and addition of triethylamine gives rise to a trimer. trans-Chelating biphosphines show more variable behaviour, and in the case of bis-1,5-diphenylphosphinopentane, a number of complexes, including one requiring C-H activation, are observed.
