In the proton decoupled ${ }^{13} \mathrm{C}$ and ${ }^{31} \mathrm{P}$ NMR spectra of $\left(\mathrm{CH}_{3}\right)_{3} \mathrm{P}=\mathrm{O}$, the number of lines observed, respectively, are
(a)two and one
(b)one and two
(c)three and one
(d)two and two.
Answer
Answer: A ✓ checked by 4AB · confidence high
The source book printed no answer; this one was worked out and checked — see the explanation.
Explanation
(CH₃)₃P=O: the three methyl carbons are equivalent, and ¹³C{¹H} shows them as a doublet (¹J_PC) — two lines; ³¹P{¹H} is a single line.