Reactivity of Yttrium Quinoline–Imine–Phenoxide Complexes Towards Inter‐ and Intramolecular Alkyl Nucleophilic Attacks

Yttrium(III) chloride complexes [YCl 2 (NNO H )] ( 1 H ) and [YCl 2 (NNO Me )] ( 1 Me ) {NNO H = 2‐ tert ‐butyl‐6‐(quinolin‐8‐yliminomethyl)phenoxide; NNO Me = 2‐ tert ‐butyl‐6‐[(2‐methylquinolin‐8‐ylimino)methyl]phenoxide} were synthesized by treating a thf solution of YCl 3 at room temperature with the NNO H ‐H and NNO Me ‐H ligands {NNO H ‐H = 2‐ tert ‐butyl‐6‐(quinolin‐8‐yliminomethyl)phenol; NNO Me ‐H = 2‐ tert ‐butyl‐6‐[(2‐methylquinolin‐8‐ylimino)methyl]phenol}, which were previously deprotonated with potassium tert ‐butoxide or thallium ethoxide. Surprisingly, reaction of 1 H with the Grignard reagent MeMgBr to prepare the corresponding dialkyl derivative led to the formation of the tetranuclear magnesium dimer [Mg 2 BrCl{NN(Me)O H }(thf)] 2 {NN(Me)O H =2‐ tert ‐butyl‐6‐[1‐(quinolin‐8‐ylamido)ethyl]phenoxide} ( 2 ), whose structure was determined by single‐crystal X‐ray diffraction. By reacting the neutral ligand NNO H ‐H withY(CH 2 SiMe 3 ) 3 · 2thf in toluene at low temperature the alkyl complex [Y(CH 2 SiMe 3 ){NN(CH 2 SiMe 3 )O}(thf)] {NN(CH 2 SiMe 3 )O = 2‐ tert ‐butyl‐6‐[1‐(quinolin‐8‐ylamido)‐2‐trimethylsilanylethyl]phenoxide} ( 3 ) was isolated. The supposed reaction mechanism leading to the formation of 3 was simulated by using the PM6 Hamiltonian. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)