31P NMR Spectra of Chelated (Diphosphine)rhodium Complexes in Solution

Article abstract of DOI:10.1021/ja00412a019

The 31P<1H> FT NMR spectra of Rh complexes that form in solution via ligand exchange of diphosphines with HRh(CO)(PPh3)3 have been scanned in order to characterize the complexes that form since with certain diphosphines such solutions catalyze selective olefin hydroformilation.It is shown that these diphosphines readily form Rh complexes under NMR conditions that exhibit 16-line multiplet spectra.The multiplets were simulated with AB2X and ABCX (A, B, C = 31P, X = 103Rh) models and are attributed to approximately trigonal-bipyramid complexes of formula HRh(CO)(P<*>P)(PR3), )1.5>2, and HRh(CO)(P<*>P)(P<*>P))^m, where R = PPh3 or PEtPh2, m = monodentate, and P<*>P = certain diphosphines including <(2,2-dimethyl-1,3-dioxolane-4,5-diyl)bis(methylene)>bis(diphenylphosphine), diop, trans-1,2-bis-(diphenylphosphino)methyl)cyclobutane, t-bdcb, 1,1'-bis(diphenylphosphino)ferrocene, fdpp-1, and 1,1'-bis(bis(p-(trifluoromethyl)phenyl)phosphino)ferrocene, fdpp-2.