Hafnium complexes with versatile β-diketiminate ligands: Synthesis, spectroscopic investigation and volatility study

•A series of β-diketiminate hafnium(IV) complexes prepared.•All the complexes were characterized by spectroscopic methods.•The solid state structure of 3c and 4a were examined by single crystal XRD.•The thermal stability and volatility of the compounds were reported.

Synthesis and spectral investigation of four novel β-diketiminate hafnium(IV) chloride complexes cis-dichloro-bis(2,4-bis(phenylimino)pent-3-ene)-hafnium (4a), cis-dichloro-bis(2,4-bis(4-methylphenylimino)pent-3-ene)-hafnium (4b), cis-dichloro-bis(2,4-bis(4-methoxyphenylimino)pent-3-ene)-hafnium (4c) and cis-dichloro-bis(2,4-bis(4-chlorophenylimino)pent-3-ene)-hafnium (4d) are reported. All complexes (4a–d) were characterized by spectroscopic methods (1H NMR, 13C NMR and mass) and elemental analysis. The solid-state structure of compound 4a was further examined by single crystal X-ray diffraction. The X-ray structure of 4a reveals that the complex is monomeric with the hafnium center in a distorted octahedral geometry, and the chloride ligands are in a cis arrangement. The thermal stability and volatility of the compounds were probed by TGA/DSC tests demonstrating the potential utility of compounds (4a–d) as precursors for CVD/ALD thin film growth below 200 °C.

Graphical abstractFour new β-diketiminate hafnium(IV) chloride complexes were synthesized and characterized. Volatile trends are established for four new β-diketiminate hafnium(IV) chloride complexes. Based on the low heats of enthalpy, high volatility is expected.Figure optionsDownload full-size imageDownload as PowerPoint slide