Hafnium Trialkyls Stabilized by Bulky,Electron‐Rich Aminopyridinates

A series of hafnium aminopyridinates were synthesized and spectroscopically analyzed. In addition, selected examples of these hafnium complexes were characterized by X‐ray single crystal structure analysis. The aminopyridinato ligands used here carry an additional dialkylamine substituent to enhance the electron donating ability of the ligands. Structural data and low temperature NMR spectroscopic investigations are indicative of the increased donating ability of the ligands. Ethylene polymerization studies revealed a rather low catalytic activity most likely due to catalyst instability. Details of the deactivation reaction were investigated by NMR spectroscopy.