Gas-phase studies of copper(I)-mediated CO(2)extrusion followed by insertion of the heterocumulenes CS(2)or phenylisocyanate

摘要

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 C(6)H(5)CS(2)(-)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.