Stereochemical dependence of ¹³C shieldings and ¹³C–³¹P couplings in phosphonates of known geometry. Is there a Karplus-type relationship for P–C–C–C coupling?

15 January 1976

journal article
Published by Canadian Science Publishing in Canadian Journal of Chemistry

Vol. 54 (2) , 231-237
https://doi.org/10.1139/v76-036

Abstract

¹³C nmr chemical shifts and ¹³C–³¹P couplings through one to five bonds are reported for seven dimethylphosphono compounds of known geometry. Vicinal couplings are maximal for a dihedral angle of 180° and are severely attenuated by OH substitution, particularly when the OH is trans-coplanar to the carbon terminus of the coupling path. When a cyclopropyl system is part of the C–C–C–P path the J values are much less than those predicted on the basis of dinedral angle. A highly asymmetric dihedral dependence of vicinal J's is suggested. Some 'non-W' long range C–P couplings through saturated networks are found. The 'gauche-γ' shift of the —P(O)(OCH₃)₂ group is about 2 ppm.

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Stereochemical dependence of 13C shieldings and 13C–31P couplings in phosphonates of known geometry. Is there a Karplus-type relationship for P–C–C–C coupling?

Abstract

Keywords

Stereochemical dependence of ¹³C shieldings and ¹³C–³¹P couplings in phosphonates of known geometry. Is there a Karplus-type relationship for P–C–C–C coupling?