Oxidative addition of diethyldichalcogenanes Et 2 E 2 (E = S, Se, Te) to bis[bis(trimethylsilyl]amido]germylene and -stannylene M[N(SiMe 3 ) 2 ] 2 (M = Ge, Sn) proceed with formation of the corresponding bis(ethylchalcogenato)797 S (1), Se (2), Te (3)] and -stannanes (Me 3 Si) 2 N) 2 Sn(EEt) 2 [E = S (4), Se (5), Te (6)]. The solid state structures of 1-6 were determined by single-crystal X-ray diffraction.

Zinc phenoxide complexes L 1 ZnOAr 1 – 4 (L 1 =Me 2 NC 2 H 4 NC(Me)CHC(Me)O) and L 2 ZnOAr 5 – 8 (L 2 =Me 2 NC 3 H 6 NC(Me)CHC(Me)O) with donor‐functionalized β ‐ketoiminate ligands (L 1/2 ) and OAr substituents (Ar=Ph 1 , 5 ; 2,6‐Me 2 ‐C 6 H 3 2 , 6 ; 3,5‐Me 2 ‐C 6 H 3 3 , 7 ; 4‐Bu‐C 6 H 4 4 , 8 ) with tuneable electronic and steric properties were synthesized and characterized. 1 – 8 adopt binuclear structures in the solid state except for 5 , while they are monomeric in CDCl 3 solution. 1 – 8 are active catalysts for the ring opening polymerization (ROP) of lactide (LA) in CH 2 Cl 2 at ambient temperature and the catalytic activity is controlled by the electronic and steric properties of the OAr substituent, yielding polymers with high average molecular weight ( M n ) and moderately controlled molecular weight distribution (MWDs). 1 and 5 showed a living polymerization character and kinetic studies on the ROP of L –LA with 1 and 5 proved first order dependencies on the monomer concentration. Homonuclear decoupled 1 H‐NMR analyses of polylactic acid (PLA) formed with rac ‐LA proved isotactic enrichment of the PLA microstructure.

Oxidative addition reactions of dialkylchalcogenanes R2E2 and [Me2Si(Nt-Bu)2]Ge 1 yielded bis(alkylchalcogeno)germanes Me2Si(Nt-Bu)2Ge(ER)2 (R = Et, E = S 2, Se 3; R = Me, E = Se 4) and digermanes [Me2Si(Nt-Bu)2Ge(EEt)]2 (E = S 5, Se 6). The reaction of 1 with Et2Te2 proceeds with formation of Me2Si(Nt-Bu)2Ge(TeEt)27, which slowly converts into the Te-bridged complex [Me2Si(Nt-Bu)2GeTe]28. 1-6 and 8 were characterized by single crystal X-ray diffraction.

The heteroleptic complex LZnEt [(1); L = MeNacac = MeNC(Me)CHC(Me)O] containing the sterically less demanding N,O-chelating ketoiminate (MeNacac) ligand was synthesized by reaction of ZnEt 2 with an equimolar amount of MeNacacH, whereas the reaction with two equivalents MeNacacH gave the homoleptic complex L 2 Zn 5. 1 reacts with ArOH (Ar = 2,6-Me 2 -Ph) with ethane elimination and formation of LZnOAr (2). Addition of the Lewis base dmap (dmap = 4-dimethylamino pyridine) to 1 and 2 yielded the corresponding Lewis acid-base adducts dmap-Zn(L)Et 3 and dmap-Zn(L)OAr 4. Compounds 1-5 were characterized by heteronuclear NMR ( 1 H, 13 C) and IR spectroscopy, elemental analysis, and single-crystal X-ray dif-[a] Synthesis and Characterization The reaction of ketoimine LH [L = MeNacac = MeNC(Me)-CHC(Me)O] with an equimolar amount of diethylzinc in THF at -60°C occurred with elimination of ethane and formation of Scheme 1. Synthesis of 1-5.

Heteroleptic zinc complexes containing side‐arm donor‐functionalized tridentate β‐ketoiminate ligands were obtained from metalation reactions of β‐ketoimines L1/2/3Do1/2/3/4H [L1 = {(OC(Me)C(H)C(Me)NCH2CH2Do)}, L2 = {(OC(Me)C(H)C(Me)NCH2CH2CH2Do)}, L3 = {(OC(OMe)C(H)C(Me)NCH2CH2Do)}; Do1 = NMe2, Do2 = NEt2; Do3 = Pyr, Do4 = OMe] with equimolar amounts of Zn[N(SiMe3)2]2 [L1Do1ZnN(SiMe3)2 (1), L1Do2ZnN(SiMe3)2 (2)] and ZnEt2 [L1Do3ZnEt (3), L2Do3ZnEt (4), L3Do1ZnEt (5), L3Do4ZnEt (6)]. Analogous reactions of AlMe3 and Cp*MMe3 with L1Do1/2H yielded homoleptic aluminum [L1Do1AlMe2 (7), L1Do2AlMe2 (8), L2Do1AlMe2 (9)], titanium [L1Do2Ti(Me2)Cp* (10)] and zirconium complexes [L1Do2Zr(Me2)Cp* (11)]. In addition, 7 reacts with an ethereal HCl solution with methane elimination and formation of L1Do1Al(Cl)Me (12) and L1Do1AlCl2 (13), whereas the reaction with one and two equivalents of 2,6‐dimethylphenol yielded L1Do1Al(Me)O‐2,6‐Me2C6H3 (14) and L1Do1Al(O‐2,6‐Me2C6H3)2 (15). The complexes were characterized by elemental analysis, 1H, 13C NMR, and IR spectroscopy and single‐crystal X‐ray analysis (2, 4, 7, 10, 12–14).