Herein, 1,2,3-selenadiazoles were instantly prepared by hand grinding the reactants via a solventless process and tested for their ability to act as a source of selenium for the synthesis of CdSe magic-sized nanoclusters (MSNCs) with size below 2 nm. The current study describes the use of different 1,2,3-selenadiazole derivatives, viz. small chain aliphatic, long chain aliphatic, acetophenone, and aromatic derivatives, in the preparation of CdSe MSNCs. The study was carried out to check the effects of different functionalities of the precursor on the formation of MSNCs of CdSe. The MSNCs prepared using a variety of selenium precursors were analyzed by various spectroscopic techniques. A characteristic doublet in the absorption spectra and broad emission profile consistently indicated that the employed selenadiazoles were useful for the selective fabrication of single family MSNCs of CdSe, and the formation of regular quantum dots was suppressed.