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Chiral Diamine Bis(phenolate) Ti IV and Zr IV Complexes – Synthesis, Structures and Reactivity

2011; Wiley; Volume: 2011; Issue: 27 Linguagem: Inglês

10.1002/ejic.201100470

1099-0682

Sónia Barroso, Pedro Adão, M. Teresa Duarte, Auke Meetsma, João Costa Pessoa, M.W. Bouwkamp, Ana M. Martins,

Organoboron and organosilicon chemistry

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.