Dicopper Alkyl Complexes: Synthesis, Structure, and Unexpected Persistence

Published on 2018-08-10T11:19:43Z (GMT) by
Cationic μ-alkyl dicopper complexes [Cu<sub>2</sub>(μ-η<sup>1</sup>:η<sup>1</sup>-R)­DPFN]­NTf<sub>2</sub> (R = CH<sub>3</sub>, CH<sub>2</sub>CH<sub>3</sub>, CH<sub>2</sub>C­(CH<sub>3</sub>)<sub>3</sub>; DPFN = 2,7-bis(fluoro-di(2-pyridyl)methyl)-1,8-naphthyridine NTf<sub>2</sub><sup>–</sup> = N­(SO<sub>2</sub>CF<sub>3</sub>)<sub>2</sub><sup>–</sup>) were synthesized by treatment of the acetonitrile-bridged dicopper complex [Cu<sub>2</sub>(μ-η<sup>1</sup>:η<sup>1</sup>-NCCH<sub>3</sub>)­DPFN]­(NTf<sub>2</sub>)<sub>2</sub> with LiR or MgR<sub>2</sub>. Structural characterization by X-ray crystallography and NMR spectroscopy revealed that the alkyl ligands symmetrically bridge the two copper centers, and the complexes persist in room-temperature solution. Notably, the μ-methyl complex showed less than 20% decomposition after 34 days in room-temperature THF solution. Treatment of the μ-methyl complex with acids allows installation of a range of monoanionic bridging ligands. However, surprisingly insertion into the dicopper–carbon bond was not observed upon addition of a variety of reagents, suggesting that these complexes exhibit a fundamentally new reactivity profile for alkylcopper species. Electrochemical characterization revealed oxidation–reduction events that evidence putative mixed-valence dicopper alkyl complexes. Computational studies suggest that the dicopper–carbon bonds are highly covalent, possibly explaining their remarkable stability.

Cite this collection

Ziegler, Micah S.; Torquato, Nicole A.; Levine, Daniel S.; Nicolay, Amélie; Celik, Hasan; Tilley, T. Don (2018): Dicopper Alkyl Complexes: Synthesis, Structure, and

Unexpected Persistence. ACS Publications. Collection.