Zinc complexes [LZnR] containing tridentate β-ketiminate ligands with an additional side-arm donor {referred to as [NNO] ligands; (6), Et (7), Cl (9)} as well as cationic derivatives with a weakly coordinating anion [LZn][Al(OC(CF 3 ) 3 ) 4 ] [L = L 1 (4), L = L 2 = (10)], a basestabilized complex [L 2 Zn(dmap)Et] (8; dmap = 4-(dimethylamino)pyridine), and a base-free complex without a sidearm donor [L 3 ZnEt] [12, L 3 = OC(Me)C(H)C(Me)N-2,6-iPr 2 C 6 H 3 ] were synthesized and characterized by singlecrystal X-ray diffraction (1, 2, 3, 8, 9, 11, and 12). The ringopening polymerization (ROP) of rac-lactide was studied [a]
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.
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).
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