We report for the first time the direct deposition of crystalline molybdenum sulfide (MoS2) using a single-source precursor based on tetrakis(diethylaminodithiocarbomato)molybdate(IV) (abbreviated as Mo(Et2NCS2)(4)). The chemistry of this precursor adsorbed on a range of substrates (silicon, germanium, gold-coated germanium, nickel, etc.) has been studied using in situ X-ray photoelectron spectroscopy. The Mo(Et2NCS2)(4) precursor can be evaporated at 300degreesC; its vapor adsorbs on most surfaces at room temperature and decomposes by 400degreesC to form crystalline MoS2. Using this method, high-quality, basal plane-oriented MoS2 can be grown on nickel by a one-step thermal evaporation process for the first time. Interestingly, choosing elemental substrates which form eutectic alloys with gold favors the elimination of sulfur from the MoS2 film. This results in Mo intermetallic compound formation at the eutectic temperatures of the An and substrate element. Unpredecented low-temperature growth of tetragonal MoSi2 or orthorhombic MoGe2 on Au-coated silicon or germanium, respectively, has been obtained via this eutectic phase-mediated diffusional reaction. Hollow carbon nanofibers are produced if the precursor is dosed onto Au-Si substrate at 1000degreesC, mediated by the catalytic effect of Au-Mo.