Titanium Complexes of Chelating Bis(phenolato) Ligands with Long Titanium−Sulfur Bonds. A Novel Type of Ancillary Ligand for Olefin Polymerization Catalysts

Abstract

The sulfide-linked bis(phenol) tbmpH2 (tbmp = 2,2‘-thiobis(6-tert-butyl-4-methylphenolato)) gives a series of titanium complexes of the formula [Ti(tbmp)X2]2 or [Ti(tbmp)(L)X2] (L = two-electron ligand, X = one-electron ligand). The molecular structures of [Ti(tbmp)(OiPr)2]2 and of [Ti(tbmp){C6H4(CH2NMe2)-2}Cl] were determined by single-crystal X-ray structural analyses. An unusually long titanium−sulfur bond of ∼270 pm is observed in both complexes which contain a six-coordinate titanium center. Variable-temperature NMR spectroscopy shows a fluxional coordination of the chelating aryl group in [Ti(tbmp){C6H4(CH2NMe2)-2}Cl].

Bis(amido)titanium complexes having chelating diaryloxo ligands bridged by sulfur or methylene and their catalytic behaviors for ring-opening polymerization of cyclic esters

“…1.830 A), due to the decreased p-donation from oxygen atoms by coordination of the sulfur-bridging atom to titanium metal center. The Ti-O distances in 2 are comparable to the diisopropoxo complex 6 (1.892 A) [17], and longer than those in the corresponding chloride complex 5 (1.846 A) [17], aryl complex 7 (1.855 A) [9a] and Cp complex (1.827 A) 8 in the titanium complex with the tbp ligand. The Ti-O distances in the methylene-bridged complex 4 are longer than that of the a series of titanium complexes with methylene-bridged bis(aryloxo) ligand (1.751-1.788 A) [19][20][21] and the other titanium complex with monodentate aryloxo or alkoxo ligands [22][23][24][25][26][27], due to the p-donation from the nitrogen atoms to the metal center [28].…”

“…2 and 3 demonstrate the molecular structures of 2 and 4 elucidated by X-ray crystallographic analyses and Table 1 bond distances and angles. Both 2 and 4 were obtained as mononuclear complexes, in sharp contrast to the dinuclear structures of the corresponding chloro and alkoxo complexes having t Bu 2 tbp ligand, {Ti( t Bu 2 tbp) Cl 2 } 2 (5) [11a] and {Ti( t Bu 2 tbp)(O i Pr) 2 } 2 (6) [17]. The coordination geometry around the titanium center in 2 can be described as pseudo C s symmetric trigonal bipyramidal in which one of the two diethylamido ligands and the sulfur atom of the t Bu 2 tbp ligand occupy the apical positions.…”

“…The complex 4 has a pseudo C s symmetric tetrahedral structure. The Ti-S bond length in 2 (2.783(1) A) is longer than those in the corresponding dichloro complex 5 (2.664(2) A) [11a], diisopropoxo complex 6 (2.719 (1) A) [17], and aryl complex Ti( t Bu 2 tbp)(o-CH 2 NMe 2 C 6 H 4 )Cl (7: 2.704 (1) A) [17], and shorter than that in a cyclopentadienyl (Cp) complex, Ti( t Bu 2 tbp)CpCl (8: 2.907 (1) A) [18]. The Ti-O distances in the sulfur-bridged complex 2 (av.…”

Use of microwave technology for the synthesis of organotitanium(IV) and organozirconium(IV) complexes with HPOH, HO∩N∩OH and HO∩N∩SH type of ligands

“…The use of these derivatives as reagents [10], leaving groups or protective groups is now becoming common in many of the reactions [11]. It became clear that the transmetallation of classical ''carbanions'' using titanating agents produces new reagents [12] which display a high degree of chemo-, regio-and stereo-selectivity. Keeping all these facts under consideration during the present investigations we have synthesized and screened some biologically potent ligands and their organotitanium(IV) and organozirconium(IV) complexes.…”

Syntheses of group 4 transition metal complexes bearing 2-pyridinethiolate ligands and their catalytic activities for ethylene polymerization

“…To our knowledge, only three structurally characterized Cp-free titanium thiolate complexes have been reported, TiCl 2 (S-t-Bu) 2 (diars) (diars ¼ o-phenylene bis(dimethylarsine)) [23], [Li(OEt 2 ) 3 ][Ti III (SAr) 4 ] (Ar ¼ 2,4,6-triisopropylphenyl) [24] and [NH 2 Me 2 ] 2 [Ti(S 2 C 6 H 4 ) 3 ] [25]. We expected that chelating coordination could stabilize metale sulfur covalent bond, and synthesized a titanium tris (2-pyridinethiolate) complex, Ti(6-H-SPy) 3 Cl$THF (1) (6-H-SPy ¼ 2-pyridinethiolate) [26], as well as lanthanoid complexes, [Ln(6-H-SPy) 2 (hmpa) 3 ]I (Ln ¼ Pr, Nd, Sm, Eu, Er, Yb) [27] and Sm(h 8 -C 8 H 8 )(6-H-SPy)(hmpa) 2 [28]. Although sulfurcontaining compounds often act as catalyst poison, the titanium tris(pyridinethiolate) complex 1 showed moderate activities for the polymerization of ethylene and styrene upon activation with MAO [26].…”