Transition-Metal Complexes of Heavier Cyclopropenes: Non-Dewar-Chatt-Duncanson Coordination and Facile Si═Ge Functionalization

Paresh Kumar Majhi; Michael Zimmer; Bernd Morgenstern; David Scheschkewitz

doi:10.1021/jacs.1c04419

Transition-Metal Complexes of Heavier Cyclopropenes: Non-Dewar-Chatt-Duncanson Coordination and Facile Si═Ge Functionalization

J Am Chem Soc. 2021 Jun 23;143(24):8981-8986. doi: 10.1021/jacs.1c04419. Epub 2021 Jun 9.

Authors

Paresh Kumar Majhi¹, Michael Zimmer¹, Bernd Morgenstern¹, David Scheschkewitz¹

Affiliation

¹ Krupp-Chair of General and Inorganic Chemistry, Saarland University, 66123 Saarbrücken, Germany.

PMID: 34107218
DOI: 10.1021/jacs.1c04419

Abstract

Transition-metal complexes of cyclopropenes occur as fleeting intermediates of numerous metal-catalyzed organic transformations. A heavier analogue has now been obtained from the reaction of an NHC-stabilized silagermenylidene, bis(1,5-cyclooctadiene)nickel(0), and 1 equiv of N-heterocyclic carbene (NHC). The residual chloro functionality at the germanium end of the coordinated Ge═Si moiety of the thus formed 1H-disilagermirene is easily exchanged by treatment with anionic nucleophiles, which provides access to a series of differently substituted Si₂Ge-cyclopropenes as nickel complexes in excellent yields. NMR spectroscopic data, X-ray crystallographic analysis, and DFT calculations indicate a coordination mode different from the metallacyclopropane and π-complex extremes of the Dewar-Chatt-Duncanson model: the σ-component of the Ge═Si double bond acts as donor and acceptor, leaving behind a nearly unsupported Si-Ge π-bond.