A silyliumylidene cation stabilized by an amidinate ligand and 4-dimethylaminopyridine

The synthesis and reactivity of a silyliumylidene cation stabilized by an amidinate ligand and 4-dimethylaminopyridine (DMAP) are described. The reaction of the amidinate silicon(I) dimer [LSi:]₂ (1; L=PhC(NtBu) ₂) with one equivalent of N-trimethylsilyl-4-dimethylaminopyridinium triflate [4-NMe₂C₅H₄NSiMe₃]OTf and two equivalents of DMAP in THF afforded [LSi(DMAP)]OTf (2). The ambiphilic character of 2 is demonstrated from its reactivity. Treatment of 2 with 1 in THF afforded the disilylenylsilylium triflate [L′₂(L)Si]OTf (3; L′=LSi:) with the displacement of DMAP. The reaction of 2 with [K{HB(iBu)₃}] and elemental sulfur in THF afforded the silylsilylene [LSiSi(H){(NtBu)₂C(H)Ph}] (4) and the base-stabilized silanethionium triflate [LSi(S)DMAP]OTf (5), respectively. Compounds 2, 3, and 5 have been characterized by X-ray crystallography. 1 becomes 2: The singlet silyliumylidene cation 2, which is stabilized by both an amidinate ligand and 4-dimethylaminopyridine (DMAP), can be synthesized by the reaction of the amidinate Si^I dimer 1 with N-trimethylsilyl-4-dimethylaminopyridinium triflate and DMAP (see scheme). The ambiphilic character of 2 can be demonstrated by its reactivity.