In a previous contribution, we have reported on a convenient and high yield synthesis of the disilene trans-[(TMS)(2)N(eta(1)-Me5C5)-Si=Si(eta(1)-Me5C5)N(TMS)(2)] (2). Herein, we show the reactions of 2 with N2O and S-g. The former reaction affords two isomeric (cis- and trans-) dioxadisiletane ring compounds. To the best of our knowledge, this is the first report where both cis- and trans-isomers are isolated from the same disilene precursor and characterized structurally by single-crystal X-ray diffraction (XRD) studies. The reaction of 2 with elemental sulfur yields only the trans-isomer. To investigate this dissimilar reaction pattern exhibited by 2, computational studies were performed. Density functional theory (DFT) calculations showed that the two dioxadisiletane ring isomers are isoenergetic, with the trans isomer being slightly more stable than the cis counterpart, by 3.3 kcal/mol, while that is not the case with sulfur. All the isolated compounds are characterized by single-crystal XRD studies, multinuclear NMR spectroscopy, and electron ionization mass spectrometry (EI-MS).