Formation of a borylene by photolysis of an overcrowded bis(methylseleno)borane

Article abstract of DOI:10.1016/S0040-4039(99)01036-9

A novel bis(methylseleno)borane 3 bearing a very bulky aryl group, 2,4,6tris[bis(trimethylsilyl)methyl]phenyl (Tbt), on the boron atom was synthesized. Photolysis of 3 gave the corresponding monovalent boron species, borylene TbtB: (4), the formation of which was confirmed by the trapping reactions with benzil, phenanthrenequinone, and dimethyl disulfide. Irradiation of 3 in the absence of a trapping reagent did not afford the expected diborene but a selenium-containing five-membered boracycle, 1,2,4,3,5-triselenadiborolane 9.