Formation and infrared spectroscopic characterization of carbon suboxide complexes TM-η 1 -C 3 O 2 and the inserted ketenylidene complexes OCTMCCO (TM=Cu, Ag, Au) in solid neon.

The reactions of coinage metal atoms Cu, Ag and Au with carbon suboxide (C 3 O 2 ) are studied by matrix isolation infrared spectroscopy. The weakly bound complexes TM-η 1 -C 3 O 2 (TM=Cu, Ag, Au), in which the carbon suboxide ligand binds to the metal center in the monohapto fashion are formed as initial reaction products. The complexes subsequently isomerize to the inserted products OCTMCCO upon visible light (λ = 400-500 nm) excitation. The analysis of the electronic structure using modern quantum chemistry methods suggests that the linear OCTMCCO complexes are best described by the bonding interactions between the TM + cation in the electronic singlet ground state and the [OC…CCO] - ligands in the doublet state forming two TM +  ← ligands σ donation and two TM +  → ligands π backdonation bonding components. In addition, the CuCCO, AgCCO and AuCCO complexes are also formed, which are predicted to be bent.