Gas-phase studies of copper(I)-mediated CO2 extrusion followed by insertion of the heterocumulenes CS2 or phenylisocyanate

The gas‐phase extrusion–insertion reactions of the copper complex [bathophenanthroline (Bphen)Cu^I(O₂CC₆H₅)]^2-, generated via electrospray ionization, was studied in a linear ion trap mass spectrometer with the combination of collision‐induced dissociation (CID) and ion‐molecule reaction (IMR) events. Multistage mass spectrometry (MSⁿ) experiments and density functional theory (DFT) demonstrated that extrusion of carbon dioxide from [(Bphen)Cu(O₂CC₆H₅)]^2- (CID) gives the organometallic intermediate [(Bphen)Cu(C₆H₅)]^2-, which subsequently reacts with carbon disulfide (IMR) via insertion to yield [(Bphen)Cu (SC(S)C₆H₅)]²⁻. The fragmentation of the product ion resulted in the formation of [Bphen]²⁻, [(Bphen)Cu]^- and C₆H₅CS₂⁻ under CID conditions. The formation of the latter two charge separation products thus provides evidence of C–C bond formation in the IMR step. Although analogous studies with isocyanate, which is isoelectronic with CS₂, showed a poor reactivity in the gas phase, the mechanistic understanding obtained from these model studies encourages future development of a solution phase protocol for the synthesis of amides from carboxylic acids and isocyanates mediated by copper(I) complexes.