Tris(4-hydroxy-3,5-diisopropylbenzyl)amine as a new bridging ligand for novel trinuclear titanium complexes

Abstract Tris(4-hydroxy-3,5-diisopropylbenzyl)amine ( LH 3 ) was synthesized by the reaction of 2,6-diisopropylphenol and hexamethylenetetramine in the presence of p -toluenesulfonic acid or paraformaldehyde. Its solid state structure was determined by single crystal X-ray diffraction. Its fully deprotonated specie, (4-O-3,5- i -Pr 2 PhCH 2 ) 3 N ( L ), was used to form novel trinuclear half-sandwich titanocene complexes, namely [(η 5 -C 5 Me 5 )TiCl 2 ] 3 L ( 1 ) and [(η 5 -C 5 Me 5 )Ti(OMe) 2 ] 3 L ( 2 ), which were then tested for the syndiospecific polymerization of styrene in the presence of methylaluminoxane (MAO) cocatalyst. Their catalytic properties were directly compared with those of trichloro(pentamethylcyclopentadienyl)titanium(IV) ( 3 ) and dichloro(2,6-diisopropylphenolato)(pentamethylcyclopentadienyl)titanium(IV) ( 4 ). 1 /MAO and 2 /MAO systems showed higher activities towards styrene polymerization than the mononuclear catalytic systems 3 /MAO and 4 /MAO, giving syndiotactic polystyrene of high molecular weight.