[Se(CH(2)C(O)CH(3))(3)][B(12)F(11)NH(3)]: The first selenium cation with three β-ketone substituents

The reaction of [Se(8)][B(12)F(11)NH(3)](2) with acetone and subsequent crystallization from acetone/diethyl ether yielded the selenium cation [Se(CH(2)C(O)CH(3))(3)](+) as a by-product, which is stabilized by the weakly coordinating undeca­fluorinated anion [B(12)F(11)NH(3)](−). While attempting to crystallize pure [Se(8)][B(12)F(11)NH(3)](2), the structure of the isolated product, namely, tris­(2-oxoprop­yl)selenium 1-ammonio­undeca­fluoro­dodeca­borate, was surprising. The cation [Se(CH(2)C(O)CH(3))(3)](+) represents the first example for a cationic selenium compound with three ketone functional groups located in the β-position with respect to the selenium atom. The cation possesses almost trigonal–pyramidal C (3) symmetry and forms hydrogen bonds to the ammonio group of the anion.