In the pursuit of terminal tin chalcogenides, heteroleptic stannylenes bearing terphenyl and hexamethyldisilazide ligands were reacted with carbodiimides to yield the respective guanidinato complexes. Further supported by quantum chemical calculations, this revealed that the iso-propyl-substituted derivative provides the maximum steric protection achievable. Oxidation with elemental selenium produced monomeric terminal tin selenides with four-coordinate tin centres. In reactions with N2O as oxygen transfer reagent, silyl migration towards putative terminal tin oxide intermediates gave rise to tin complexes with terminal –OSiMe3 functionality. To prevent silyl migration, the silyl groups were substituted for cyclohexyl moieties. This analogue exhibited distinctively different reactivities towards selenium and N2O, yielding a tetraselenastannolane and chalcogenide-bridged dimeric compounds, respectively.