CaSi2 is de-intercalated by reacting it with aqueous HCl solution at ca. -30 °C. The resultant Si-NS are thought to adopt a buckled layered structure where each Si atom is bonded to three other framework Si atoms and a terminal atom/functional group (SiSi3X, Figure ). We previously used 1D and 2D 1 H and Si solid-state NMR experiments to show that majority of the Si atoms are terminated with H atoms (SiSi3H), leading to the conclusion that the structure of Si-NS can be best described as "silicane". However, Si solid-state NMR spectra reveal additional NMR signals hypothesized to arise from OH and Cl terminated Si atoms (SiSi3OH and SiSi3Cl, Figure ). Energy-dispersive X-ray spectroscopy (EDS) images, infrared spectroscopy (IR), and X-ray photoelectron spectroscopy (XPS) also suggest the presence of Cl terminated silicon atoms in Si-NS. and SiSi3Cl groups. This structure was not obtained quantum chemical calculations. (B) 1D (upper, middle) 1 H→ Si CP-CPMG and (lower) direct excitation Si NMR spectra of Si-NS. The dashed, red line corresponds to an analytical fit.