SCAVENGING OF HEXAFLUOROSELENOACETONE BY CYCLOADDITIONS WITH DIENES AND PREPARATION OF HG[SECF(CF3)2]2 AND (CH3)3SISECF(CF3)2

Bis(perfluoroisopropylseleno)mercury (2) was obtained from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-diselenetane (1) and HgF2 in DMF, and (perfluoroisopropylseleno)trimethylsilane (3) from 2 and (CH3)3SiI. The reaction of 2 with (C2H5)2AlI as well as the pyrolysis of 1 yield a deep purple liquid in very small amounts, not sufficient for further characterisation, which is assumed to be hexafluoroselenoacetone (4). However, 4 is formed as an intermediate in the reaction of hexafluoropropene with CsF and selenium and can be trapped by isoprene or anthracene to form 5a, 5b, and 6, respectively. In boiling benzene a transformation of (CF3)2C = Se from 6 to 2,3-dimethyl-1,3-butadiene is accomplished yielding 7 in a retro Diels-Alder cleavage.