An integrated experimental and theoretical investigation on Cu(hfa)₂·TMEDA: structure, bonding and reactivity

The physico-chemical properties of the β-diketonate diamine Cu(II) compound with hfa (1,1,1,5,5,5-hexafluoro-2-4-pentanedionate) and TMEDA (N,N,N′,N′ tetramethylethylenediamine), Cu(hfa)₂·TMEDA, have been thoroughly investigated via an integrated multi-technique experimental–computational approach. In the newly found orthorhombic polymorph, as revealed by low temperature single-crystal X-ray studies, the complex is present as a monomer with a distorted octahedral geometry at the Cu(II) centre. The compound sublimates, without premature side decompositions, at 343 K and 10⁻³ Torr. The structural, vibrational, electronic and thermal behavior of the neutral Cu(hfa)₂·TMEDA complex has been investigated along with its fragmentation pathways, initiated by the release of an anionic hfa ligand with formation of a positive Cu(hfa)·TMEDA⁺ ion. Joint experimental and theoretical analyses led to the rationalization of the first fragmentation steps in terms of the Cu(II)–ligands bonding properties and Jahn–Teller distortion. The present study suggests applications of Cu(hfa)₂·TMEDA as a precursor for copper and copper oxide materials by Chemical Vapor Deposition.