In order to fit the RESPDOR dephasing curves (Figure ) and confirm that the Cl atoms are covalently bonded to Si the Cl quadrupolar coupling constant (CQ) must be measured. Plane-wave DFT calculations predict that the Cl CQ is ca. 40 MHz, similar to that which was previously determined with nuclear quadrupole resonance (NQR) spectroscopy for perchloropolysilanes. Unfortunately, static Cl WURST-CPMG experiments on Si-NS did not yield any NMR signal after ca. 3 hours of acquisition (Figure ). Based on the large predicted CQ of 40 MHz for Si-NS and the bandwidth of the WURST pulses, ca. 20-25 subspectra would be required to observe the entire quadrupolar powder pattern of Si-NS, making the static experiment impossible at a magnetic field of 14.1 T or less. In comparison, high signal-to-noise Cl WURST-CPMG NMR signal was observed for transplatin in only ca. 8.5 mins (Figure ). Transplatin was used for comparison here because it has a similar Cl wt. % to Si-NS and a Cl CQ of ca. 35 MHz. With the failure of the Cl WURST-CPMG experiments on the Si-NS a different strategy was required to measure the Cl CQ. Recently, we described techniques to indirectly map out wideline MAS 195 Pt NMR spectra through a spy nucleus such as 1 H. This work was directly inspired by similar dipolar dephasing experiments that were used to map out the quadrupolar powder patterns of Al and 14 N. Motivated by these prior studies, we performed 1 H{ Cl} DE-RESPDOR experiments on Si-NS where the offset of the Cl saturation pulse offset was varied in steps of 500 kHz over a range of +3 to -4 MHz (Figure ). Plotting the signal dephasing as a function of the Cl saturation pulse offset enables the reconstruction of the Cl central transition (CT) quadrupolar powder pattern for the Si-NS (Figure ). Numerical simulations of the MHz (h = 0), in close agreement with that predicted by plane-wave DFT (40 MHz; Figure ). Notably, the 1 H-detected Cl NMR spectrum of the Si-NS was acquired in only 1.4 hours at B0 = 14.1 T.