Extremely Large One-Bond ~(31)P~(13)C and Two-Bond ~(31)P~(18)O Isotope Shifts in [(H_3C)_2CH]_3Si-O-Cident to P, a New Representative of #lambda#~3-Phosphaalkynes, and Isotope Shifts of Several Derivatives and some #lambda#~3-Phosphaalkenes

摘要

The structure of the heteroatom-substituted #lambda#~3-phosphaalkyne [(H_3C)_2CH]_3Si-O-Cident to P (1) was derived from the ~(31)P, ~(13)C, ~(29)Hi and ~(17)O MR spectra. The phosphorus atom of the non-isotope-enriched compound exhibits an extremely negative ~(31)P~(13)C one-bond and ~(31)P~(18)O two-bond isotope shift of -0.209 and -0.094 ppm, respectively. The ~(31)P{~aH} MR spectrum shows all carbon, silicon and oxygen satellite signals of the [mono- ~(13)C]-, [mono- ~(29)Hi]- and [mono- ~(18)O]- as well as the [bis- ~(13)C, ~(29)Hi]- and [bis- ~(13)C, ~(13)C]isotopomers; even over five bonds a ~(31)P~(13)C isotope effect can also be observed. Additivity of the corresponding isotope effects has been confirmed. The coupling constant ~1J(~(31)P, ~(13)C) is unexpectedly large, 91.9 Hz. ~(31)P~(13)C one-bond isotope shifts of other #lambda#~3-phosphaalkynes and #lambda#~3-phosphaalkenes are presented and discussed.