The Theoretical and Experimental Investigation of the Fluorinated Palladium β-Diketonate Derivatives: Structure and Physicochemical Properties

To search for new suitable Pd precursors for MOCVD/ALD processes, the extended series of fluorinated palladium complexes [Pd(CH3CXCHCO(R))(2)] with beta-diketone [tfa-1,1,1-trifluoro-2,4-pentanedionato (1); pfpa-5,5,6,6,6-pentafluoro-2,4-hexanedionato (3); hfba-5,5,6,6,7,7,7-heptafluoro-2,4-heptanedionato (5)] and beta-iminoketone [i-tfa-1,1,1-trifluoro-2-imino-4-pentanonato (2); i-pfpa-5,5,6,6,6-pentafluoro-2-imino-4-hexanonato (4); i-hfba-5,5,6,6,7,7,7-heptafluoro-2-imino-4heptanonato (6)] ligands were synthesized with 70-80% yields and characterized by a set of experimental (SXRD, XRD, IR, NMR spectroscopy, TG) and theoretical (DFT, Hirshfeld surface analysis) methods. Solutions of Pd beta-diketonates contained both cis and trans isomers, while only trans isomers were detected in the solutions of Pd beta-iminoketonates. The molecules 2-6 and new polymorphs of complexes 3 and 5 were arranged preferentially in stacks, and the distance between molecules in the stack generally increased with elongation of the fluorine chain in ligands. The H . . . F contacts were the main ones involved in the formation of packages of molecules 1-2, and C . . . F, F . . . F, NH . . . F contacts appeared in the structures of complexes 4-6. The stability of complexes and their polymorphs in the crystal phases were estimated from DFT calculations. The TG data showed that the volatility differences between Pd beta-iminoketonates and Pd beta-diketonates were minimized with the elongation of the fluorine chain in the ligands.

Automated summary

In this study, a series of fluorinated palladium complexes with beta-diketone and beta-iminoketone ligands were synthesized and characterized. The solutions of beta-diketonates contained both cis and trans isomers, while only trans isomers were detected in the solutions of beta-iminoketonates. The effect of elongation of the fluorine chain in the ligands on the structure and stability of the complexes was investigated using experimental and theoretical methods.