For experiment b load the HMQC-type pulse program. You may have to switch rf. cables and filters, since now °'P is the detected nucleus X. You have to set:

td2: 256 data points in F, tdl: 128 data points in F; sw2: 1 ppm swl: 12 ppm o1: middle of °'P NMR spectrum o2: middle of ¹H NMR spectrum 03: middle of ¹³C NMR spectrum p1: 90° *'P transmitter pulse p2: 180° *'P transmitter pulse p3, p4: 90° ¹³C decoupler pulse dl:2s d2: 1/[2(C,P)] = 25 ms, calculated from "J(C,P) = 20 Hz initial value for t; evolution: 3 μs increment for ¢; evolution = 1/[2-sw1] proton decoupler attenuation and 90° pulse for CPD ns: 4

5. Processing

In both cases apply zero-filling in F; to 256 real data points to obtain a matrix of 512x256 real data points. Use unshifted sinusoidal windows in both dimensions. Apply complex Fourier transformation corresponding to the N-type signal selection using the quadrature-off mode in F). Phase correction is not necessary, since the data are pro-cessed in magnitude mode.

6. Result

The figure shows the results of both experiments obtained on an AMX-500 spectrometer with an inverse triple resonance probe-head. In both 2D spectra an isotope effect for C-1 of triphenylphosphine can be observed. Compare the signal-to-noise ratio of the two methods by inspecting the rows containing the signals.