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Heterobimetallic Metal–Amidinate Complexes by Stepwise Metalation of Methanetrisamidines

2013; Wiley; Volume: 2013; Issue: 31 Linguagem: Inglês

10.1002/ejic.201300939

1099-0682

Benjamin Gutschank, Melike Bayram, Stephan Schulz, Dieter Bläser, Christoph Wölper,

Asymmetric Synthesis and Catalysis

Abstract The acidity of the four N–H groups in methanetrisamidine 1c differs significantly, thereby allowing stepwise metalation by metal organic compounds such as ZnMe 2 , AlMe 3 , and GaMe 3 . 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 ZnMe 2 , AlMe 3 , and GaMe 3 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 AlMe 3 , 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 ).