Bis(trifluoromethyl)disulfide and the EtP 4 Phosphazene Base—Formation of a Bench‐Stable [EtP 4 SCF 3 ] + [SCF 3 ] − Salt

ABSTRACT The reaction of the {(Et 2 N) 3 P═N} 3 P═N t Bu phosphazene base (EtP 4 ) with bis(trifluoromethyl)disulfide, (F 3 CS) 2 , selectively affords [EtP 4 SCF 3 ][SCF 3 ], which arises from formal heterolytic S─S bond cleavage. The phosphazenium salt represents the first structurally characterized SCF 3 substituted iminium derivative. Subsequent reaction with methyl halides MeX (X = Br, I) leads to selective substitution of the anionic SCF 3 moiety and facilitates isolation of the corresponding [EtP 4 SCF 3 ]X (X = Br, I) salts. Treatment of [EtP 4 SCF 3 ][SCF 3 ] with trimethylsilyl halides Me 3 SiX (X = Cl, Br) affords halogenophosphonium halide salts [({Et 2 N} 3 P═N) 3 PX]X (X = Cl, Br), via removal of the iminium unit at the phosphazene center. All compounds were characterized by multinuclear NMR spectroscopy, single‐crystal X‐ray diffraction experiments, and elemental analyses. Both SCF 3 units are chemically addressable and can be employed in further functionalization. In contrast, no reaction of (F 3 CS) 2 is observed when the iminophosphorane (C 4 H 8 N) 3 P═N t Bu is employed under comparable conditions, whereas the phosphanes PMe 3 and P(NEt 2 ) 3 undergo conversion to the corresponding difluorophosphoranes. These observations underline the exceptional ability of the EtP 4 phosphazene base to promote bond activation and to stabilize the resulting reactive SCF 3 .