Four types of trialkylphosphine-stabilized copper dialkylaluminum ethanedithiolate complexes with the compositions [(Pr3PCuSC2H4SAlR2)-Pr-i](2) (R = Me, Et, Pr-i, Bu-t, vinyl), [((Pr3PCu)-Pr-i)(3)(SC2H4S)(2)AlR2] (R = Et), [(Me3P)(3)CuSC2H4SAlR2] (R = Me, Et), and [(Me3P)(4)Cu][SC2H4SAlR2] (R = Me, Et, Pr-i) have been synthesized and structurally characterized by X-ray diffraction. The first series features an eight-membered (CuSAlS)(2) ring as the core structure. The trimethylphosphine complexes can be distinguished as nonionic and ionic compounds, depending on the amount of trimethylphosphine. In systematic thermogravimetric studies, the complexes were converted into the ternary semiconductor CuAlS2. In this process, a novel wurtzite-type CuAlS2 phase was identified. Binary copper sulfide is observed as a minor side product in thermolysis reactions when volatile trialkylaluminum is released. The thermolysis reactions are completed at temperatures between 330 and 470 degrees C, depending on the aluminum alkyls. The Cu/Al ratio and phase purity of the thermolysis products were determined by Rietveld analysis of the powder X-ray diffraction patterns and by inductively coupled plasma optical emission spectroscopy measurements. To our knowledge, this is the first study of molecular single-source precursors for CuAlS2.