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Benzimidazolin-2-iminato Hafnium Complexes: Synthesis, Characterization, and Catalytic Addition of Alcohols to Carbodiimides
journal contribution
posted on 2020-08-04, 15:44 authored by Maxim Khononov, Heng Liu, Natalia Fridman, Matthias Tamm, Moris S. EisenA series of asymmetric
imidazolin-2-iminato and benzimidazolin-2-iminato
hafnium(IV) complexes were synthesized and fully characterized including
single-crystal X-ray diffraction. The asymmetric imidazolin-2-iminato
hafnium complex exhibits a shorter Hf–N bond length as compared
with the corresponding benzimidazolin-2-iminato hafnium complex. These
complexes were successfully utilized as catalysts for the addition
of alcohols to carbodiimides. The synthesis of several active intermediates
and kinetics, thermodynamics, and stoichiometric reaction studies
allowed us to propose a mechanism for the reaction. The X-ray crystal
structure of the monomeric Hf(OtBu)4 is presented.