title: A donor-stabilized zwitterionic "half-parent" phosphasilene and its unusual reactivity towards small molecules.
abstract: The stabilization of the labile, zwitterionic "half-parent" phosphasilene 4 L'Si=PH (L'=CH[(C=CH2)CMe(NAr)2]; Ar=2,6-iPr2C6H3) could now be accomplished by coordination with two different donor ligands (4-dimethylaminopyridine (DMAP) and 1,3,4,5-tetramethylimidazol-2-ylidene), affording the adducts 8 and 9, respectively. The DMAP-stabilized zwitterionic "half-parent" phosphasilene 8 is capable of transferring the elusive parent phosphinidene moiety (:PH) to an unsaturated organic substrate, in analogy to the "free" phosphasilene 4. Furthermore, compounds 4 and 8 show an unusual reactivity of the Si=P moiety towards small molecules. They are capable of adding dimethylzinc and of activating the S-H bonds in H2S and the N-H bonds in ammonia and several organoamines. Interestingly, the DMAP donor ligand of 8 has the propensity to act as a leaving group at the phosphasilene during the reaction. Accordingly, treatment of 8 with H2S affords, under liberation of DMAP, the unprecedented thiosilanoic phosphane LSi=S(PH2) 16 (L=HC(CMe[2,6-iPr2C6H3N])2). Compounds 4 and 8 react with ammonia both affording L'Si(NH2)PH2 17, respectively. In addition, the reaction of 8 with isoproylamine, p-toluidine, and pentafluorophenylhydrazine lead to the corresponding phosphanylsilanes L'Si(PH2)NHR (R=iPr 18 a; R=C6H5-CH3 18 b, R=NH(C6F5) 18 c), respectively.
authors.affiliation: Department of Chemistry, Metalorganics and Inorganic Materials, Technische Universität Berlin, Strasse des 17. Juni 135, Sekr. C2, 10623 Berlin (Germany), Fax: (+49) 30-314-29734.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Hansen
authors.forename: Tibor
authors.initials: T
authors.lastname: Szilvási
authors.forename: Burgert
authors.initials: B
authors.lastname: Blom
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Irran
authors.forename: Matthias
authors.initials: M
authors.lastname: Driess
keywords: phosphinidine; phosphorus; silanes; silicon; zwitterions