Heterobimetallic Metal-Amidinate Complexes by Stepwise Metalation of Methanetrisamidines
The acidity of the four N–H groups in methanetrisamidine 1c differs significantly, thereby allowing stepwise metalation by metal organic compounds such as ZnMe2, AlMe3, and GaMe3. Dinuclear complexes 3a–c were formed under kinetic control in the reactions of 1c with 2 equiv. of the metal organic compounds at low temperatures, whereas prolonged reaction times at elevated temperature (100 °C) with 4 equiv. of ZnMe2, AlMe3, and GaMe3 yielded the corresponding tetranuclear complexes 4a–c. The different acidity of the four N–H groups also allowed the stepwise metalation of 1c by two different metal organic complexes with the formation of the heterobimetallic complexes 5a and 5b. In addition, transmetalation by Zn/Al exchange was observed in the reaction of 3c with AlMe3, yielding the corresponding dinuclear aluminium complex 3a. The complexes were characterized by NMR and IR spectroscopy and single‐crystal X‐ray diffraction (3a, 4b, 5a).
Dedicated to Prof. Bernt Krebs the occasion of his 75th birthday.