The electronic structure of small clusters forming the inorganic cores in cadmium thiolate complexes is analyzed on the basis of semiempirical quantum chemical calculations. Orbital energies, atom charges, and peculiarities of chemical bond formation are considered for sphalerite lattice fragments CdxSy (x less than or equal to 20, less than or equal to 35). The variation of calculated properties with size is nonmonotonous, but the tendency for band structure formation occurs with increasing size. The HOMO-LUMO energy differences for some structures are close to the experimental observations for the Cd thiolate complexes. Calculations show the major role of tetrahedral coordination in the properties of these structures.