We report on thesynthesis of an authentic Sn=B-moietyrealizedin a stannaborenyl anion and stannaborenium cation. Starting withan oxidative addition of boron tribromide to a stannylene-phosphine Lewis pair o-C6H4(Ar*BrSn-BBr2-PPh2) (2a) Ar* = C6H3(2,6-Trip)(2), Trip = 2,4,6-C6H2 iPr(3) was synthesized. Reduction of 2a with magnesium yields the Grignard-type stannaborene o-C6H4(Ar*Sn=B-{PPh2}-MgBr-{thf})(2) (3)(2) featuring a Sn=B double bond and a B-Mg interaction. Followingan alternative protocol, hydride substitution at 2a yields the tinhydride o-C6H4(Ar*HSn-BBr2-PPh2) (4a). HBr elimination of 4a in reaction with (NHC)-N-Me ((NHC)-N-Me = 1,3,4,5-tetramethylimidazol-2-ylidene) gives the carbene and phosphine stabilized stannyl-borylene o-C6H4(Ar*BrSn-B-{PPh2}-{(NHC)-N-Me}) (5) after simultaneous bromide transfer from boron to tin. In reaction of 5 with Li-Al-(OC-{CF3}(3))(4) or Na-BAr4F in a mixture of o-DFB/benzene a stannaborene o-C6H4(Ar*Sn=B-{PPh2}-{(NHC)-N-Me})(+) 6 stabilized by the respective weakly coordinating anion was isolated (Ar-F = C6H3-3,5-(CF3)(2), o-DFB = o-difluorobenzene). The phosphine and NHC-supported stannaborenium cation 6 adds ammonia at room temperature under splitting of a N-H bond and formation of Sn-NH2 and B-H bonds to give o-C6H4(Ar*-{H2N}-Sn-BH-{PPh2}-{(NHC)-N-Me})(+) (7).
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