Synthesis of Cobalt-Tin and -Lead Tetrylidynes - Reactivity Study of the Triple Bond.

Tetrylidynes [TbbSn≡Co(PMe3)3] (1a) and [TbbPb≡Co(PMe3)3] (2) (Tbb = 2,6-[CH(SiMe3)2]2-4-(t-Bu)C6H2) are accessed for the first time via a substitution reaction between [Na(OEt2)][Co(PMe3)4] and [Li(thf)2][TbbEBr2] (E = Sn, Pb). Following an alternative procedure the stannylidyne [Ar*Sn≡Co(PMe3)3] (1b) was synthesized by hydrogen atom abstraction using AIBN from the paramagnetic hydride complex [Ar*SnH=Co(PMe3)3] (4) (AIBN = azobis(isobutyronitrile)). The stannylidyne 1a adds two equivalents of water to yield the dihydroxide [TbbSn(OH)2CoH2(PMe3)3] (5). In reaction of the stannylidyne 1a with CO2 a product of a redox reaction [TbbSn(CO3)Co(CO)(PMe3)3] (6) was isolated. Protonation of the tetrylidynes occurs at the cobalt atom to give the metalla-stanna vinyl cation [TbbSn=CoH(PMe3)3][BArF4] (7a) [ArF = C6H3-3,5-(CF3)2]. The analogous germanium and tin cations [Ar*E=CoH(PMe3)3][BArF4] (E = Ge 9, Sn 7b) (Ar* = C6H3(2,6-Trip)2, Trip = 2,4,6-C6H2iPr3) were also obtained by oxidation of the paramagnetic complexes [Ar*EH=Co(PMe3)3] (E = Ge 3, Sn 4), which were synthesized by substitution of a PMe3 ligand of [Co(PMe3)4] by a hydridoylene (Ar*EH) unit.