Heterobimetallic Coinage Metal-Ruthenium Complexes Supported by Anionic N-Heterocyclic Carbenes

The lithium complexes [(WCA-NHC)Li(toluene)] of anionic N-heterocyclic carbenes with a weakly coordinating borate moiety (WCA-NHC, WCA=B(C6F5)(3), NHC=IDipp=1,3-bis(2,6-diisopropylphenyl)imidazolin-2-ylidene) were used for the preparation of silver(I) or copper(I) WCA-NHC complexes. While the reactions in THF with AgCl or CuCl afforded anionic mono- and dicarbene complexes with solvated lithium counterions [Li(THF)(n)](+) (n=3, 4), the reactions in toluene proceeded with elimination of LiCl and formation of the neutral phosphine and arene complexes [(WCA-NHC)M(PPh3)] and [(WCA-NHC)M(eta(2)-toluene)] (M=Ag, Cu). The latter were used for the preparation of chlorido- and iodido-bridged heterobimetallic Ag/Ru and Cu/Ru complexes [(WCA-NHC)M(mu-X)(2)Ru(PPh3)(eta(6)-p-cymene)] (M=Ag, Cu, X=Cl; M=Ag, X=I). Surprisingly, these complexes resisted the elimination of CuCl, AgCl, or AgI, precluding WCA-NHC transmetalation.

Automated summary

This study explores the use of lithium complexes with weakly coordinating borate moieties for the preparation of silver(I) or copper(I) WCA-NHC complexes. Reactions in different solvents and with different metals are investigated, revealing various transformations during the process.