Partial double bond character in chalcogen compounds of stanna-closo-dodecaborate.

The following chalcogen compounds of stanna-closo-dodecaborate were synthesized and characterized: the tetrameric oxide [(O-SnB(11)H(11))(4)](8-) from the reaction with hydrogen peroxide and the sulfide and selenide [S-SnB(11)H(11)](2-), [Se-SnB(11)H(11)](2-) from the reaction with elemental sulfur and selenium, respectively. The stannaborate derivatives were characterized by (119)Sn Mössbauer spectroscopy and single crystal structural analysis. The character of the bond between the tin and group 16 elements was studied extensively by using quantum chemical methods.