of buckled layers of sp hybridized silicon atoms that are bonded to three other framework Si atoms and a terminal atom or functional group such as H, Cl or an -OH group. Here, we apply 1 H{ Cl} and Si{ Cl} Resonance-Echo Saturation-Pulse DOuble-Resonance (RESPDOR) solidstate NMR experiments to directly confirm the presence of chlorinated Si atoms within Si-NS. Plotting the observed 1 H{ Cl} RESPDOR dephasing as a function of the Cl saturation pulse offset enables measurement of the Cl central-transition (CT) quadrupolar powder pattern and the chlorine quadrupolar coupling constant (CQ). Modelling the 1 H{ Cl} RESPDOR dephasing curve shows that the Si-Si interlayer spacing is approximately 6 Å. Plane-wave DFT calculations suggest that the direct band gap transition of Si-NS decreases with increasing chlorination, suggesting that chlorination is a viable pathway to tune the band gap for applications. Two-dimensional silicon nanosheets (Si-NS) have attracted considerable attention for their potential as next-generation semiconductors for many electronic, optoelectronic, spintronic, energy storage and catalytic applications. One route to making Si-NS is to perform topotactic deintercalation of alkali metal silicides, such as calcium disilicide (CaSi2).