Stabilization and Activation: New Alkyl Complexes of Zinc, Magnesium and Cationic Aluminium Featuring Chelating Bisguanidine Ligands

In this work we report on the synthesis of new zinc, magnesium and cationic aluminium alkyl as well as Mg aryl complexes featuring chelating bisguanidine ligands [2,8-bis(tetramethylguanidino) naphthalene (btmgn) and 1,2-bis(tetramethylguanidino) benzene (btmgb)]. The bond properties in the complexes are analyzed with a combination of experiments and quantum chemical calculations. VT NMR studies shed light on the fluxional processes within the complexes and their activation barriers. The compounds are stable against alkylation of the C=N imine bonds of the guanidino groups and might represent interesting alkyl transfer reagents and (co-)catalysts. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)