An unexpected transmetalation intermediate: isolation and structural characterization of a solely CH3 bridged di-copper(I) complex

Structural characterization of unsupported, two metal centres bridging methyl groups is rare. They have been proposed as transmetalation intermediates in cuprate chemistry, but as yet no structural evidence has been presented. We have isolated a di-copper(I) complex with solely a methyl ligand bridging two Cu(I) atoms, representing a new bonding mode of CH3.