Chiral Diamine Bis(phenolate) TiIV and ZrIV Complexes – Synthesis, Structures and Reactivity

Abstract Neutral and cationic titanium and zirconium diamine bis(phenolate) complexes supported by chiral ligands L 1 and L 2 are described [L 1 = ( R )‐6,6′‐{1‐(dimethylamino)propan‐2‐ylazanediyl}bis(methylene)‐bis(2,4‐di‐ tert ‐butylphenolate);L 2 = ( S )‐6,6′‐{(1‐ethylpyrrolidin‐2‐yl)methylazanediyl}bis(methylene)‐bis(2,4‐di‐ tert ‐butylphenolate)]. Complexes[TiL(O i Pr) 2 ] [L = L 1 ( 1 ), L 2 ( 2 )], [TiL 2 X(O i Pr)] [X = Cl ( 3 ), CH 2 Ph ( 4 )], [TiL 1 (CH 2 Ph) 2 ] ( 5 ), [ZrLCl 2 ] [L = L 1 ( 6 ), L 2 ( 7 )] and [ZrL(CH 2 Ph) 2 ] [L = L 1 ( 8 ), L 2 ( 9 )] are C 1 ‐symmetric species readily prepared in moderate to high yields. Cationic compounds were obtained from complexes 5 , 8 and 9 through reactions with B(C 6 F 5 ) 3 . The monocationic species reveal the η 2 ‐binding character of the benzyl groups and noncoordinated [B(C 6 F 5 ) 3 (CH 2 Ph)] – . Complexes 5 – 9 were tested in the polymerization of ethylene and propylene upon activation with modified methylaluminoxane (MMAO), B(C 6 F 5 ) 3 or [NHMe 2 Ph] + as cocatalysts. The [ZrL 1 Cl 2 ]/MMAO and [ZrL 1 (CH 2 Ph) 2 ]/B(C 6 F 5 ) 3 systems revealed high activities in the polymerization of propylene (2.1 × 10 3 and 1.5 × 10 3 g pol mmol cat –1 h –1 , respectively), leading to atatic polypropylene, whereas the titanium complexes showed no activity.