Copper sulfide nanocrystals support localized surface plasmon resonances in the near-infrared wavelengths and have significant potential as active plasmonic nanomaterials due to the tunability of this optical response. While numerous strategies exist for synthesizing copper sulfide nanocrystals, few methods result in nanocrystals with both controlled morphological shapes and crystallinity. Here, we synthesize and characterize ultrathin (<5 nm) Cu9S5 nanosheets that are formed by solventless thermolysis, utilizing Cu alkanethiolates as single-source precursors. Layered Cu alkanethiolate precursors adopt a highly ordered structure which can be further stabilized in the presence of Cl- and also serve to template the formation of nanosheets. We show that, in the absence of Cl-, only isotropic and disk-like Cu2-xS nanocrystals form. These findings offer further insight into the use of layered metal organic single-source precursors as templates for anisotropic nanocrystal growth.