Syntheses, characterization of N-functionalized benzyl zinc, cadmium and manganese (II) compounds

Treatment of [LiL·TMEDA] (1) {L = [2-Me2NCH2C6H4CH(SiMe3)]−} with half equivalent of ZnCl2, CdCl2 or MnCl2 in diethyl ether gave the crystalline compound [ML2] {M = Zn (2), Cd (3) and Mn (4)}, respectively. Reaction of 1 with one equivalent of ZnCl2 in diethyl ether afforded the crystalline compound [Zn(Cl)L·TMEDA] (5) in good yield. An eight-membered cyclic homoleptic binuclear compound [ZnL′]2 (6) {L′ = [(2-Me2NCH2C6H4CH)2SiMe2]2−} was prepared from the reaction of (2-Me2NCH2C6H4CH2)2SiMe2 (B′) with two equivalents of n-BuLi and one equivalent of ZnCl2. All of the crystalline compounds 1–6 were well characterized by 1H NMR, 13C NMR spectroscopy, elemental analyses and single crystal X-ray crystallography. In addition, moderate activity for the polymerization of rac-lactide to poly(lactic acid) (PLA) was found in compounds 2 and 5, and all the resulting polylactides are most predominantly heterotactic-rich.

Graphical abstractZn(II), Cd(II) and Mn(II) complexes [ML2] [M = Zn (2), Cd (3), Mn (4)], [LZnCl·TMEDA] (5) and [ZnL′]2 (6) {L = [2-Me2NCH2C6H4CH(SiMe3)]−, L′ = [(2-Me2NCH2C6H4CH)2SiMe2]2−} were prepared from [LiL·TMEDA] (1) and corresponding metal chloride. X-ray structures of 1–6 were reported. Compounds 2 and 5 exhibited moderate activity towards polymerization of rac-lactide.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Six novel N-functionalized benzyl metal compounds were synthesized and characterized. ► Compounds 2 and 5 exhibited moderate activity towards polymerization of rac-lactide to poly(lactic acid). ► All the resulting polylactides are most predominantly heterotactic-rich.