[Se(CHC(O)CH)][BFNH]: The first selenium cation with three β-ketone substituents.

The reaction of [Se][BFNH] with acetone and subsequent crystallization from acetone/diethyl ether yielded the selenium cation [Se(CHC(O)CH)] as a by-product, which is stabilized by the weakly coordinating undeca-fluorinated anion [BFNH]. While attempting to crystallize pure [Se][BFNH], the structure of the isolated product, namely, tris-(2-oxoprop-yl)selenium 1-ammonio-undeca-fluoro-dodeca-borate, was surprising. The cation [Se(CHC(O)CH)] 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 symmetry and forms hydrogen bonds to the ammonio group of the anion.