An original synthesis of the fused pyranoquinoxaline dithiolene ligand qpdt2− is discussed in detail. The most intriguing step is the introduction of the dithiolene moiety by Pd-catalyzed carbon–sulfur coupling. The corresponding MoIVO complex (Bu4N)2[MoO(qpdt)2] (2) underwent reversible protonation in a strongly acidic medium and remained stable under anaerobic conditions. Besides, 2 was found to be very sensitive towards oxygen, as upon oxidation it formed a planar dithiin derivative. Moreover, the qpdt2− ligand in the presence of [MoCl4(tBuNC)2] formed a tetracyclic structure. The products resulting from the unique reactivity of qpdt2− were characterized by X-ray diffraction, mass spectrometry, NMR spectroscopy, UV/Vis spectroscopy, and electrochemistry. Plausible mechanisms for the formation of these products are also proposed.