In situ synthesis and crystal growth of copper(I) carbonyl trifluoroacetate: a dinuclear [Cu₂(O₂CCF₃)₂(CO)₂] core structure confirmed

Abstract

The solid state structure of the long known but inadequately characterized compound, namely the mixed ligand copper(I) carbonyl trifluoroacetate, [Cu2(O2CCF3)2(CO)2] (1), has been determined by single crystal X-ray crystallography. Instead of the previously assigned tetranuclear core structure, its main building block is now confirmed to be a dinuclear copper(I) unit that is cis-bridged by two trifluoroacetate ligands. The Cu · · · Cu separation within the unit is 3.1382(6) Å. Additionally, each copper center has one terminally bound carbonyl with a Cu–C distance of 1.806(3) Å. In the solid state, 1 displays a 1D chain structure comprised of the [Cu2(μ 2-O2CCF3)2(CO)2] units held by axial Cu · · · O interactions at 2.2181(13) Å.

Structure and Bonding in Copper(I) Carbonyl and Cyanide Complexes

“…Uncharacteristically for the soft copper(I) ion, the CuCO unit is often found coordinated to the oxygen donor anions: alkoxide, − carboxylate, sulfonate, and phosphonate . These complexes, which are usually formed under 1 atm of CO, form oligomers and polymers, such as III – V . , The cubane geometry reflected in III is very common for Cu(I), most commonly being encountered with μ 3 -halide corners.…”