ABSTRACT
The linker-bridged distannene [(2,6-Mes2)C6H3Sn]2C12H8 (1) featuring an acenaphthene linker and the sterically demanding terphenyl substituent Ar(Me) (= C6H3-2,6-Mes2; Mes = C6H2-2,4,6-Me3) was prepared and characterized by single-crystal analysis, NMR spectroscopy, as well as elemental analysis. Furthermore, the reactivity of distannene 1 and previously reported distannenes 2 and 3, bearing either a naphthalene or a 9,9-dimethylxanthene backbone and the terphenyl substituent Ar(Me), as well as bis(stannylene) 4, featuring a 9,9-dimethylxanthene backbone and the terphenyl substituent Ar(iPr) (= C6H3-2,6-Trip2; Trip = C6H2-2,4,6-i-Pr3), toward terminal alkynes at ambient temperature was investigated, leading to the formal [2 + 2] cycloaddition products 5-9. The reactions of distannene 1 with trimethylsilylacetylene and phenylacetylene, the reaction of distannene 2 with trimethylsilyl-acetylene, as well as the reaction of bis(stannylene) 4 with phenylacetylene show reversibility, while distannenes 2 and 3 react irreversibly with phenylacetylene at room temperature. A van't Hoff analysis of variable-temperature (1)H NMR spectra of the cycloadduct of the reaction of distannene 1 with trimethylsilylacetylene afforded a dissociation enthalpy (ΔHdiss) of 71.6 kJ·mol(-1), which is in surprisingly good agreement with the results of accompanying DFT calculations (ΔHdiss = 70.9 kJ·mol(-1)).
ABSTRACT
N-[2-P(i-Pr)(2)-4-methylphenyl](2)(-) (PNP) pincer complexes of tin(IV) and tin(II), [(PNP)SnCl(3)] (2) and [(PNP)SnN(SiMe(3))(2)] (3), respectively, were prepared and characterized by X-ray diffraction, solution and solid state NMR spectroscopy, and (119)Sn Mössbauer spectroscopy. Furthermore, (119)Sn cross polarization magic angle spinning NMR spectroscopic data of [Sn(NMe(2))(2)](2) are reported. Compound 2 is surprisingly stable toward air, but attempts to substitute chloride ligands caused decomposition.
