Structure and Bonding in a Diamond-Shaped Tin Cluster Possessing a cyclo-Sn Core.

A tetrameric cluster composed entirely of (aryl)Sn units, [DMPSn] (DMP=2,6-dimesitylphenyl), has been prepared by reduction of [DMPSnCl] with a variety of reductants. This cluster was characterized in solution by multinuclear NMR spectroscopies, as well as in the solid-state by single crystal X-ray diffraction analysis. This species is stereochemically nonrigid in solution and possesses a cyclo-Sn core whose DMP substituents are equivalent at higher temperatures.

Generation of Ti Alkyne Trimerization Catalysts in the Absence of Strong Metal Reductants.

Low-valent Ti species have typically been synthesized by the reaction of Ti halides with strong metal reductants. Herein we report that Ti species can be generated simply by reacting Ti imido complexes with 2 equiv of alkyne, yielding a metallacycle that can reductively eliminate pyrrole while liberating Ti. In order to probe the generality of this process, Ti-catalyzed alkyne trimerization reactions were carried out with a diverse range of Ti precatalysts.