Volatile Heterobimetallic Complexes from Pd^II and Cu^II β-Diketonates: Structure, Magnetic Anisotropy, and Thermal Properties Related to the Chemical Vapor Deposition of CuPd Thin Films

A novel approach for preparing volatile heterometallic complexes for use as precursors for the chemical vapor deposition of various materials is reported. New CuPd complexes based on β-diketonate units were prepared, and their structures and compositions were determined. [PdL₂ *CuL₂ ] (1) and [PdL₂ *Cu(tmhd)₂ ] (2) (L=2-methoxy-2,6,6-trimethylheptane-3,5-dionate; tmhd=2,2,6,6- tetramethylheptane-3,5-dionate) are 1D coordination polymers with alternating metal complexes, which are connected through weak interactions between the Cu atoms and the OCH₃ groups from the ligand of the Pd complexes. The volatility and thermal stability were studied using thermogravimetric and differential thermal analyses and mass spectrometry. Compound 1 vaporizes without decomposition into monometallic complexes. It exhibits magnetic anisotropy, which was revealed from the angular variations in the EPR spectrum of a single crystal. The vapor thermolysis process for 1 was investigated using mass spectrometry, allowing the process to be framed within the temperature range of 200-350 °C. The experimental data, supported by QTAIM calculations of the allowed intermolecular interactions, suggest that 1 likely exists in the gas phase as bimetallic molecules. Compound 1 proved to be suitable as a single-source precursor for the efficient preparation of CuPd alloy films with tunable Cu/Pd ratio. A possible mechanism for the film growth is proposed based on the reported data.