Dimerization of a marginally stable disilenyl germylene to tricyclic systems: evidence for reversible NHC-coordination

WOS: 000369642800033PubMed: 26771028Tetrasiladigermatricyclohexanes in two isomeric forms (chair and doubly-bridged tetrahedron) are obtained by the reaction of MeLi with an alpha-chlorosilyl functionalized NHC-stabilized silagermenylidene. Si-29 NMR at low temperature proves the initial formation of a monomeric NHC-adduct of a disilenyl germylene followed by cyclisation to the isomeric heavy cyclopropene. Addition of an excess of NHC stabilizes the both intermediates and demonstrates the reversibility of rate-determining initial equilibria involving NHC dissociation. Finally, a mixture of two isomeric tricyclic Si4Ge2 species is obtained: at elevated temperature the chair isomer converts to the doubly edge-bridged tetrahedron.Deutsche Forschungsgemeinschaft (DFG) [SCHE906/5-1]; Alfried Krupp von Bohlen und Halbach-Foundation; COST Action (Smart Inorganic Polymers) [CM1302]; TCIS HyderabadRamona Cullmann is acknowledged for her TOC art. Support for this study was provided by the Deutsche Forschungsgemeinschaft (DFG SCHE906/5-1), Alfried Krupp von Bohlen und Halbach-Foundation, and COST Action CM1302 (Smart Inorganic Polymers). A. J. thanks to TCIS Hyderabad for providing a knowledge exchange grant