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NMR studies of fluorocarbon diphosphines and oxy‐ and thio‐bisphosphines
Author(s) -
Kang DaeKi,
Servis Kenneth L.,
Burg Anton B.
Publication year - 1971
Publication title -
organic magnetic resonance
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0030-4921
DOI - 10.1002/mrc.1270030110
Subject(s) - chemistry , isomerization , diastereomer , fluorine , nmr spectra database , thio , diphosphines , coupling constant , nuclear magnetic resonance spectroscopy , spectral line , stereochemistry , crystallography , medicinal chemistry , computational chemistry , organic chemistry , catalysis , physics , particle physics , astronomy
Both the diphosphine CH 3 CF 3 PPCH 3 CF 3 and the thio‐bisphosphine CH 3 CF 3 PSPCH 3 CF 3 show 19 F and 31 P NMR spectra indicative of diastereomeric mixtures of d , l and meso isomers. The temperature‐dependent reversible interconversions of the isomers have been attributed to the inversion at the phosphorus atom. The equilibrium constants for the isomerization reactions have been measured at various temperatures. The fluorine NMR spectra of the meso and d , l isomers of CD 3 CF 3 PSPCD 3 CF 3 have been analyzed as M 3 XX′M 3 ′ spin systems. Good agreement is found between the observed and calculated spectra. The five‐bond fluorine‐fluorine coupling constant of the low‐field isomer is larger than that of the high‐field isomer. The 19 F NMR spectra of (CF 3 ) 2 PP(CF 3 ) 2 , (CF 3 ) 2 POP(CF 3 ) 2 , (CF 3 ) 2 PSP(CF 3 ) 2 , CH 3 CF 3 PPCH 3 CF 3 and CH 3 CF 3 PSPCH 3 CF 3 have been examined over a wide range of temperatures in an attempt to correlate the data to the geometries of these compounds.