Imidazolin-2-iminato ligand supported titanium(IV) aryloxo complexes – Syntheses and structures

Abstract We report the synthesis and structure of a series of mono-, bis- and tris- aryloxo titanium (IV) complexes supported by imidazolin-2-iminato ligands. The reaction of titanium imidazolin-2-iminato complexes [(Im R N)Ti(NMe 2 ) 3 ] [R =  t Bu ( tert -butyl) ( 1a ), Mes (mesityl) ( 1b ) and Dipp (2,6-diisopropylphenyl) ( 1c )] with various substituted phenols in 1:1 M ratio in toluene afforded the corresponding mixed mono-aryloxo imidazolin-2-iminato titanium (IV) complexes of general formulae [(Im R N)Ti(NMe 2 ) 2 (OAr′)] [(R = Mes, Ar′ = 2,6- t Bu 2 C 6 H 3 ( 2b ), 2,4- t Bu 2 -4-Me-C 6 H 2 ( 3b ), 2-Br-4,6- t Bu 2 -C 6 H 2 ( 4b ), R = Dipp, Ar′ = 2,4- t Bu 2 -4-Me-C 6 H 2 ( 3c ), 2-Br-4,6- t Bu 2 -C 6 H 2 ( 4c )]. Analogous reaction with 2 M of substituted phenols yielded the corresponding bis(aryloxo) imidazolin-2-iminato titanium (IV) complex [(Im t Bu N)Ti(NMe 2 )(OAr′) 2 ] [(Ar′ = 2-Br-4,6- t Bu 2 -C 6 H 2 ( 5a )]. The dimeric tris(aryloxo) imidazolin-2-iminato titanium (IV) complexes [{(Im R N)Ti(OAr′) 2 } 2 ] [Ar′ = 4- t BuC 6 H 4 , R =  t Bu ( 6a ) R = Mes ( 6b )] were obtained by treating complex 1a , b with 3 mols of respective aryl alcohols. Complexes 2b , 3b , 3c , 4b , 4c , 5a and 6a were characterised using single-crystal X-ray diffraction analysis. The solid-state structures of all the complexes reveal that the Ti–N iminato bond in each case is kinetically stable and strong, due to bonding of the more electronegative oxygen atom to the titanium ion.