Hafnium(IV) chloride complexes with chelating ß-ketiminate ligands: Synthesis, spectroscopic characterization and volatility study.

The synthesis and characterization of four new ß-ketiminate hafnium(IV) chloride complexes dichloro-bis[4-(phenylamido)pent-3-en-2-one]-hafnium (4a), dichloro-bis[4-(4-methylphenylamido)pent-3-en-2-one]-hafnium (4b), dichloro-bis[4-(4-methoxyphenylamido)pent-3-en-2-one]-hafnium (4c), and dichloro-bis[4-(4-chlorophenylamido)pent-3-en-2-one]-hafnium (4d) are reported. All the complexes (4a-d) were characterized by spectroscopic methods ((1)H NMR, (13)C NMR, IR), and elemental analysis while the compound 4c was further examined by single-crystal X-ray diffraction, revealing that the complex is monomer with the hafnium center in octahedral coordination environment and oxygens of the chelating N-O ligands are trans to each other and the chloride ligands are in a cis arrangement. Volatile trends are established for four new ß-ketiminate hafnium(IV) chloride complexes (4a-d). Sublimation enthalpies (ΔHsub) were calculated from thermogravimetric analysis (TGA) data, which show that, the dependence of ΔHsub on the molecular weight (4a-c) and inductive effects from chlorine (4d).

Syntheses, characterizations and thermal analyses of four novel unsymmetrical ß-diketiminates.

Four novel unsymmetrical ß-diketiminates 2-(2,6-diisopropylphenyl)amino-4-(phenyl)imino-2-pentene (4a), 2-(2,6-diisopropylphenyl)amino-4-(4-methylphenyl)imino-2-pentene (4b), 2-(2,6-diisopropylphenyl)amino-4-(4-methoxyphenyl)imino-2-pentene (4c) and 2-(2,6-diisopropylphenyl)amino-4-(4-chlorophenyl)imino-2-pentene (4d) were synthesized with a 77-84% yield, and were characterized by spectroscopic methods ((1)H NMR, (13)C NMR, IR and mass spectrometry), elemental analysis, and X-ray single-crystal diffraction, respectively. Spectroscopic and X-ray single-crystal diffraction analyses determined the structures of the four ß-diketiminates. While thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) showed two distinct endothermic peaks for each ß-diketiminate at temperatures of 92.55°C and 221.50°C (4a), 93.51°C and 238.82°C (4b), 109.60°C and 329.22°C (4c), 115.43°C and 243.25°C (4d), respectively, corresponding to their melting and boiling points.