Diversity of the Structures in a Distannene Complex and its Reduction to Generate a Six-Membered Ti2Sn4 Ring Complex

In contrast to olefin complexes, their congeners of heavier elements display various coordination modes, and their complexes may be present as bis(metallylene) complexes, with side-on coordination, as metallacyclopropanes, or as complexes. In the course of our studies on the reactivity of dilithiostannoles towards transition-metal reagents, three-membered TiSn2 and six-membered Ti2Sn4 ring complexes were obtained. According to its geometric parameters, NMR analysis, and theoretical calculations, the TiSn2 complex cannot be categorized into any of these previously described bonding modes. Therefore, a novel resonance structure has been proposed for a complex that has a delocalized sigma-orbital over the TiSn2 ring to understand its electronic structure. The mechanism for the formation of the Ti2Sn4 ring complex and its EPR spectrum are also discussed.