Abstract:Titanium complexes based on 2,2′‐thiobis[4‐(1,1,3,3‐tetramethylbutyl)phenolato] (tbop) are prepared by reaction of TiCl4 or Ti(NMe2)4 with the parent biphenol. Three new complexes are reported: [Ti2(μ‐tbop‐κ3O,S,O)(μ‐tbop‐κ2O,O)‐(tbop‐κ3O,S,O)Cl2] (1)·2 CH3CN, [Ti2(μ‐tbop‐κ3O,S,O)2Cl4] (2) and [Ti(tbop‐κ3O,S,O)2] (3). Substitution of the chlorides in 1 and 2 by 2,6‐diisopropylphenolato and imido (NtBu) ligands generates the new compounds [Ti2(μ‐tbop‐κ3O,S,O)2‐Cl2(dipp)2] (4)·Et2O and [Ti2(μ‐tbop‐κ3O,S,O)2(NtBu… Show more
“…In contrast to previously reported heteroleptic tbop-Ti catalysts, − preliminary polymerization results showed that complexes 1 − 6 when activated with aluminum alkyls were inactive in ethene polymerization. The lack of catalytic activity can explain the fact that formally considered 16-electron complexes 4 − 6 are coordinatively saturated species and there is no vacancy for the incoming olefin.…”
Section: Resultscontrasting
confidence: 76%
“…The structures of both complexes reveal eight-coordinate Zr or Hf metal centers with a dodecahedral geometry and tetrahedral aluminum atoms linked via oxygen atoms of the tbop ligands. The M−O distances are very similar in both complexes and as expected significantly longer than those for terminal Zr and Hf aryloxides 2a,d-f,8 Also M−S and M−C bond lengths in both 5 and 6 display similar trends and do not reveal unusual features. 2d,f,g,j,l, The Al−O bond lengths are close to those found in other structures of the aluminum aryloxides. , The Al−C bond lengths are clearly within the range expected for the terminal Al−C bond distances. , 1 Molecular structure of [M(μ-tbop-κ 3 O,S,O) 2 Me 2 (AlMe 2 ) 2 ] [where M = Zr ( 5 ) or Hf ( 6 )] ( 6 shown, hydrogen atoms omitted for clarity). Selected bond lengths (Å): 5 , Zr−O(1) 2.307(3), Zr−O(2) 2.225(3), Zr−S(1) 2.794(2), Zr−C(1) 2.286(4), Zr−C(2) 2.283(4), Al(1)−O(1) 1.847(3), Al(1)−O(3) 1.856(3), Al(1)−C(3) 1.959(4), Al(1)−C(4) 1.954(4); 6 , Hf−O(1) 2.306(6), Hf−O(2) 2.196(6), Hf−S(1) 2.796(4), Hf−C(1) 2.246(9), Hf−C(2) 2.260(9), Al(1)−O(1) 1.818(7), Al(1)−O(3) 1.886(6), Al(1)−C(3) 1.956(9), Al(1)−C(4) 1.934(9).…”
Section: Resultssupporting
confidence: 63%
“…Generally, two routes are used to achieve neutral [M(diaryloxides) 2 ] complexes: (a) σ-bond metathesis reaction between the bisphenols and an appropriate homoleptic metal precursor enabling either alkane, alcohol, amine, or HCl elimination; (b) salt elimination reactions between an alkali metal diaryloxide salt and MCl 4 . The convenient route to prepare [Ti(tbop-κ 3 O,S,O) 2 ] ( 1 ) as an orange-red solid was shown to be the σ-bond metathesis reaction between the tbopH 2 and [Ti(NMe 2 ) 4 ] in a 2:1 molar ratio and has been described earlier . Both zirconium and hafnium analogues 2 and 3 , respectively, were prepared efficiently by the reaction of 2 equiv of the tbopH 2 with MCl 4 under reflux in toluene as colorless, air- and moisture-sensitive compounds with concomitant elimination of 4 equiv of HCl (Scheme ).…”
Section: Resultsmentioning
confidence: 96%
“…Both zirconium and hafnium analogues 2 and 3 , respectively, were prepared efficiently by the reaction of 2 equiv of the tbopH 2 with MCl 4 under reflux in toluene as colorless, air- and moisture-sensitive compounds with concomitant elimination of 4 equiv of HCl (Scheme ). In the same conditions TiCl 4 forms the dimeric, heteroleptic complex [Ti 2 (μ-tbop-κ 3 O,S,O)(μ-tbop-κ 2 O,O)(tbop-κ 3 O,S,O)Cl 2 ], which in solution dissociates to [Ti(tbop-κ 3 O,S,O) 2 ] ( 1 ) and [Ti 2 (μ-tbop-κ 3 O,S,O) 2 Cl 2 ] . Complexes 2 and 3 are well soluble in organic solvents, and attempts to obtain them in crystalline form failed.…”
Section: Resultsmentioning
confidence: 99%
“…We have been exploring the use of the S-bridged 2,2‘-thiobis{4-(1,1,3,3-tetramethylbutyl)phenolato} (tbop) ligand for the preparation of early transition complexes, in particular titanium complexes, that might serve as catalysts for the polymerization of α-olefins. The tbop ligand was placed on Ti, and several heteroleptic, alkoxo- and aryloxo-bridged complexes containing coligands such as chlorides, imides, and monoaryloxides have been created and structurally characterized. − These complexes when activated with aluminum alkyls are highly effective heterogeneous, well-defined, single-site ethene polymerization catalysts. It has been proved that during the polymerization process the tbop ligand does not migrate to the aluminum atom of the activator and generation of active centers occurs via the abstraction of coligands from the titanium atom.…”
Complexes haVing two ancillary (tbop) 2ligands where tbopH 2 ) 2, 2′-thiobis{4-(1,1,3,3-tetramethylbutyl) Viz.,S,O) 2 ] (M ) Ti, 1; M ) Zr, 2; M ) Hf, 3), haVe been prepared in good yields by amine or HCl elimination from tbopH 2 . The 1 H and 13 C NMR studies showed that complexes 1-3 adopt in solution mononuclear structures. Treatment of 1-3 with 2 equiV or an excess of AlMe 3 generates heterometallic [M(µ-tbop-κ 3 O,S,O) 2 Me 2 (µ-AlMe 2 ) 2 ] (M ) Ti, 4; M ) Zr, 5; M ) Hf, 6) complexes. The structures of 4-6 were confirmed by NMR spectroscopy; complexes 5 and 6 were further inVestigated by X-ray crystallography. These studies showed 4-6 to be trimers either in the solid state or in solution. The crystals of 5•CH 2 Cl 2 and 6•CH 2 Cl 2 consist of eightcoordinate dimethyl Zr or Hf centers and two AlMe 2 moieties attached to oxygen atoms of the tbop ligands. The saturated coordination sphere of the metal centers in 1-6 makes them inactiVe in ethene polymerization.
“…In contrast to previously reported heteroleptic tbop-Ti catalysts, − preliminary polymerization results showed that complexes 1 − 6 when activated with aluminum alkyls were inactive in ethene polymerization. The lack of catalytic activity can explain the fact that formally considered 16-electron complexes 4 − 6 are coordinatively saturated species and there is no vacancy for the incoming olefin.…”
Section: Resultscontrasting
confidence: 76%
“…The structures of both complexes reveal eight-coordinate Zr or Hf metal centers with a dodecahedral geometry and tetrahedral aluminum atoms linked via oxygen atoms of the tbop ligands. The M−O distances are very similar in both complexes and as expected significantly longer than those for terminal Zr and Hf aryloxides 2a,d-f,8 Also M−S and M−C bond lengths in both 5 and 6 display similar trends and do not reveal unusual features. 2d,f,g,j,l, The Al−O bond lengths are close to those found in other structures of the aluminum aryloxides. , The Al−C bond lengths are clearly within the range expected for the terminal Al−C bond distances. , 1 Molecular structure of [M(μ-tbop-κ 3 O,S,O) 2 Me 2 (AlMe 2 ) 2 ] [where M = Zr ( 5 ) or Hf ( 6 )] ( 6 shown, hydrogen atoms omitted for clarity). Selected bond lengths (Å): 5 , Zr−O(1) 2.307(3), Zr−O(2) 2.225(3), Zr−S(1) 2.794(2), Zr−C(1) 2.286(4), Zr−C(2) 2.283(4), Al(1)−O(1) 1.847(3), Al(1)−O(3) 1.856(3), Al(1)−C(3) 1.959(4), Al(1)−C(4) 1.954(4); 6 , Hf−O(1) 2.306(6), Hf−O(2) 2.196(6), Hf−S(1) 2.796(4), Hf−C(1) 2.246(9), Hf−C(2) 2.260(9), Al(1)−O(1) 1.818(7), Al(1)−O(3) 1.886(6), Al(1)−C(3) 1.956(9), Al(1)−C(4) 1.934(9).…”
Section: Resultssupporting
confidence: 63%
“…Generally, two routes are used to achieve neutral [M(diaryloxides) 2 ] complexes: (a) σ-bond metathesis reaction between the bisphenols and an appropriate homoleptic metal precursor enabling either alkane, alcohol, amine, or HCl elimination; (b) salt elimination reactions between an alkali metal diaryloxide salt and MCl 4 . The convenient route to prepare [Ti(tbop-κ 3 O,S,O) 2 ] ( 1 ) as an orange-red solid was shown to be the σ-bond metathesis reaction between the tbopH 2 and [Ti(NMe 2 ) 4 ] in a 2:1 molar ratio and has been described earlier . Both zirconium and hafnium analogues 2 and 3 , respectively, were prepared efficiently by the reaction of 2 equiv of the tbopH 2 with MCl 4 under reflux in toluene as colorless, air- and moisture-sensitive compounds with concomitant elimination of 4 equiv of HCl (Scheme ).…”
Section: Resultsmentioning
confidence: 96%
“…Both zirconium and hafnium analogues 2 and 3 , respectively, were prepared efficiently by the reaction of 2 equiv of the tbopH 2 with MCl 4 under reflux in toluene as colorless, air- and moisture-sensitive compounds with concomitant elimination of 4 equiv of HCl (Scheme ). In the same conditions TiCl 4 forms the dimeric, heteroleptic complex [Ti 2 (μ-tbop-κ 3 O,S,O)(μ-tbop-κ 2 O,O)(tbop-κ 3 O,S,O)Cl 2 ], which in solution dissociates to [Ti(tbop-κ 3 O,S,O) 2 ] ( 1 ) and [Ti 2 (μ-tbop-κ 3 O,S,O) 2 Cl 2 ] . Complexes 2 and 3 are well soluble in organic solvents, and attempts to obtain them in crystalline form failed.…”
Section: Resultsmentioning
confidence: 99%
“…We have been exploring the use of the S-bridged 2,2‘-thiobis{4-(1,1,3,3-tetramethylbutyl)phenolato} (tbop) ligand for the preparation of early transition complexes, in particular titanium complexes, that might serve as catalysts for the polymerization of α-olefins. The tbop ligand was placed on Ti, and several heteroleptic, alkoxo- and aryloxo-bridged complexes containing coligands such as chlorides, imides, and monoaryloxides have been created and structurally characterized. − These complexes when activated with aluminum alkyls are highly effective heterogeneous, well-defined, single-site ethene polymerization catalysts. It has been proved that during the polymerization process the tbop ligand does not migrate to the aluminum atom of the activator and generation of active centers occurs via the abstraction of coligands from the titanium atom.…”
Complexes haVing two ancillary (tbop) 2ligands where tbopH 2 ) 2, 2′-thiobis{4-(1,1,3,3-tetramethylbutyl) Viz.,S,O) 2 ] (M ) Ti, 1; M ) Zr, 2; M ) Hf, 3), haVe been prepared in good yields by amine or HCl elimination from tbopH 2 . The 1 H and 13 C NMR studies showed that complexes 1-3 adopt in solution mononuclear structures. Treatment of 1-3 with 2 equiV or an excess of AlMe 3 generates heterometallic [M(µ-tbop-κ 3 O,S,O) 2 Me 2 (µ-AlMe 2 ) 2 ] (M ) Ti, 4; M ) Zr, 5; M ) Hf, 6) complexes. The structures of 4-6 were confirmed by NMR spectroscopy; complexes 5 and 6 were further inVestigated by X-ray crystallography. These studies showed 4-6 to be trimers either in the solid state or in solution. The crystals of 5•CH 2 Cl 2 and 6•CH 2 Cl 2 consist of eightcoordinate dimethyl Zr or Hf centers and two AlMe 2 moieties attached to oxygen atoms of the tbop ligands. The saturated coordination sphere of the metal centers in 1-6 makes them inactiVe in ethene polymerization.
Phenolates represent versatile ligand scaffolds capable of stabilizing a large variety of both oxophilic metal centers and late transition elements. Over the past 50 years, they have played a prominent role in the rise of discrete metal complexes employed to promote, initiate and/or catalyze a variety of controlled homogeneous polymerization reactions. This chapter features a selection of the most remarkable metal phenolate complexes used in the polymerization of olefins, styrene and dienes, cyclic esters and (meth)acrylates. Coordination-insertion polymerization reactions are emphasized, but other types of mechanisms are also treated. Specifically highlighted are catalytic systems where the phenolate ligands have proved valuable ancillaries, to provide either exceptional stability to active species and to generate highly productive catalysts, and/or to control the polymerization reactions, imparting a unique capacity to obtain polymers with tailored macromolecular features: molecular weights and their dispersion, (co)monomer distribution and regio/stereoselectivity
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