2025 Volume 83 Issue 6 Pages 539-548
Transition-metal complexes having metal-E triple bonds (E=heavy group 14 elements: Si, Ge, Sn, and Pb), which are generally called as tetrylyne complexes, have received great attention in their physical and chemical properties, in relation to the carbon congeners, i.e. well-known carbyne complexes. Thanks to the concept of kinetic stabilization using sterically hindered substituents, tetrylyne complexes have become accessible during the last two decades. However, despite significant progress, reactivity study of these complexes especially toward organic substrates remain limited. Our group has developed a new synthetic strategy, which allowed us to obtain neutral germylyne complexes that have metal-germanium triple bonds and silylyne complexes that have metal-silicon triple bonds of all group 6 metals (W, Mo, and Cr). Their molecular structures and bonding properties have been revealed by multiple NMR spectroscopies, single crystal-X-ray diffraction (SC-XRD) study as well as DFT calculations. Using these complexes, we found several new patterns of reactions including cycloaddition reactions ([2＋2], [2＋3], [2＋4] and combinations with intra-molecular bond activation) and activation reactions of external dihydrogen and benzene C-H bond, etc. These examples demonstrate high potential of metal-ligand cooperative activity of tetrylyne complexes at their strongly polarized triple bonds. This article describes these results on neutral germylyne and silylyne complexes.
