Unexpected Binuclear Bis(phenolato) Titanium (IV) {[(L)Ti(Ph)]₂(μ-OEt)₂} Assisted by Carbon−Oxygen Bond Cleavage and Alkali-Metal-Containing Titanium(III) Complexes [Ti(L)₂·M(solv)₂] (M = Li, Na, K; solv = THF, DME)

Titanium complex [(L)Ti(CH2Ph)2] (2) was prepared by reaction of [(L)TiCl2] (L = 2,2‘-methylenebis(6-tert-butyl-4-methylphenolato)) (1) with PhCH2MgCl in a 1:2 ratio in Et2O in 69% yield, while the reaction of 1 with PhLi under the same conditions yields [(L)Ti(Ph)2] (3) in less than 40% yield and an unexpected rare phenyl alkoxide-bridged compound {[(L)Ti(Ph)]2(μ-OEt)2}(4) in ca. 9% yield. According to the crystal structure, 2 and 3 are monomeric and tetrahedral, with boat-conformation ligands. The X-ray structure of 4 showed the complex to be dimeric, with titanium in a distorted pyramidal coordination geometry. The reduction of 1 with 1.0 equiv of LiBEt3H, excess Na/Hg, or 1.0 equiv of KC8 gave the titanium(III) salts [Ti(L)2·M(THF)2] (M = Li, 5; M = Na, 6) and [Ti(L)2·K(DME)2] (7), respectively. The molecular structures of 5 and 7 were confirmed by single-crystal X-ray analysis. The titanium atom in complexes 5 and 7 is four-coordinate, with a distorted tetrahedral arrangement and the same ligand orientations as in 2−4. The lithium atom in 5 is four-coordinate with two coordinated THF molecules, while the big potassium ion in 7 is six-coordinate with two chelated DME molecules added to the two bridging oxygen atoms of the bis(phenolato) ligands

Unexpected Binuclear Bis(phenolato) Titanium (IV) {[(L)Ti(Ph)]₂(μ-OEt)₂} Assisted by Carbon−Oxygen Bond Cleavage and Alkali-Metal-Containing Titanium(III) Complexes [Ti(L)₂·M(solv)₂] (M = Li, Na, K; solv = THF, DME)

Titanium complex [(L)Ti(CH2Ph)2] (2) was prepared by reaction of [(L)TiCl2] (L = 2,2‘-methylenebis(6-tert-butyl-4-methylphenolato)) (1) with PhCH2MgCl in a 1:2 ratio in Et2O in 69% yield, while the reaction of 1 with PhLi under the same conditions yields [(L)Ti(Ph)2] (3) in less than 40% yield and an unexpected rare phenyl alkoxide-bridged compound {[(L)Ti(Ph)]2(μ-OEt)2}(4) in ca. 9% yield. According to the crystal structure, 2 and 3 are monomeric and tetrahedral, with boat-conformation ligands. The X-ray structure of 4 showed the complex to be dimeric, with titanium in a distorted pyramidal coordination geometry. The reduction of 1 with 1.0 equiv of LiBEt3H, excess Na/Hg, or 1.0 equiv of KC8 gave the titanium(III) salts [Ti(L)2·M(THF)2] (M = Li, 5; M = Na, 6) and [Ti(L)2·K(DME)2] (7), respectively. The molecular structures of 5 and 7 were confirmed by single-crystal X-ray analysis. The titanium atom in complexes 5 and 7 is four-coordinate, with a distorted tetrahedral arrangement and the same ligand orientations as in 2−4. The lithium atom in 5 is four-coordinate with two coordinated THF molecules, while the big potassium ion in 7 is six-coordinate with two chelated DME molecules added to the two bridging oxygen atoms of the bis(phenolato) ligands

Unexpected Binuclear Bis(phenolato) Titanium (IV) {[(L)Ti(Ph)]₂(μ-OEt)₂} Assisted by Carbon−Oxygen Bond Cleavage and Alkali-Metal-Containing Titanium(III) Complexes [Ti(L)₂·M(solv)₂] (M = Li, Na, K; solv = THF, DME)

Titanium complex [(L)Ti(CH2Ph)2] (2) was prepared by reaction of [(L)TiCl2] (L = 2,2‘-methylenebis(6-tert-butyl-4-methylphenolato)) (1) with PhCH2MgCl in a 1:2 ratio in Et2O in 69% yield, while the reaction of 1 with PhLi under the same conditions yields [(L)Ti(Ph)2] (3) in less than 40% yield and an unexpected rare phenyl alkoxide-bridged compound {[(L)Ti(Ph)]2(μ-OEt)2}(4) in ca. 9% yield. According to the crystal structure, 2 and 3 are monomeric and tetrahedral, with boat-conformation ligands. The X-ray structure of 4 showed the complex to be dimeric, with titanium in a distorted pyramidal coordination geometry. The reduction of 1 with 1.0 equiv of LiBEt3H, excess Na/Hg, or 1.0 equiv of KC8 gave the titanium(III) salts [Ti(L)2·M(THF)2] (M = Li, 5; M = Na, 6) and [Ti(L)2·K(DME)2] (7), respectively. The molecular structures of 5 and 7 were confirmed by single-crystal X-ray analysis. The titanium atom in complexes 5 and 7 is four-coordinate, with a distorted tetrahedral arrangement and the same ligand orientations as in 2−4. The lithium atom in 5 is four-coordinate with two coordinated THF molecules, while the big potassium ion in 7 is six-coordinate with two chelated DME molecules added to the two bridging oxygen atoms of the bis(phenolato) ligands

Unexpected Binuclear Bis(phenolato) Titanium (IV) {[(L)Ti(Ph)]₂(μ-OEt)₂} Assisted by Carbon−Oxygen Bond Cleavage and Alkali-Metal-Containing Titanium(III) Complexes [Ti(L)₂·M(solv)₂] (M = Li, Na, K; solv = THF, DME)

Titanium complex [(L)Ti(CH2Ph)2] (2) was prepared by reaction of [(L)TiCl2] (L = 2,2‘-methylenebis(6-tert-butyl-4-methylphenolato)) (1) with PhCH2MgCl in a 1:2 ratio in Et2O in 69% yield, while the reaction of 1 with PhLi under the same conditions yields [(L)Ti(Ph)2] (3) in less than 40% yield and an unexpected rare phenyl alkoxide-bridged compound {[(L)Ti(Ph)]2(μ-OEt)2}(4) in ca. 9% yield. According to the crystal structure, 2 and 3 are monomeric and tetrahedral, with boat-conformation ligands. The X-ray structure of 4 showed the complex to be dimeric, with titanium in a distorted pyramidal coordination geometry. The reduction of 1 with 1.0 equiv of LiBEt3H, excess Na/Hg, or 1.0 equiv of KC8 gave the titanium(III) salts [Ti(L)2·M(THF)2] (M = Li, 5; M = Na, 6) and [Ti(L)2·K(DME)2] (7), respectively. The molecular structures of 5 and 7 were confirmed by single-crystal X-ray analysis. The titanium atom in complexes 5 and 7 is four-coordinate, with a distorted tetrahedral arrangement and the same ligand orientations as in 2−4. The lithium atom in 5 is four-coordinate with two coordinated THF molecules, while the big potassium ion in 7 is six-coordinate with two chelated DME molecules added to the two bridging oxygen atoms of the bis(phenolato) ligands

Unexpected Binuclear Bis(phenolato) Titanium (IV) {[(L)Ti(Ph)]₂(μ-OEt)₂} Assisted by Carbon−Oxygen Bond Cleavage and Alkali-Metal-Containing Titanium(III) Complexes [Ti(L)₂·M(solv)₂] (M = Li, Na, K; solv = THF, DME)

Titanium complex [(L)Ti(CH2Ph)2] (2) was prepared by reaction of [(L)TiCl2] (L = 2,2‘-methylenebis(6-tert-butyl-4-methylphenolato)) (1) with PhCH2MgCl in a 1:2 ratio in Et2O in 69% yield, while the reaction of 1 with PhLi under the same conditions yields [(L)Ti(Ph)2] (3) in less than 40% yield and an unexpected rare phenyl alkoxide-bridged compound {[(L)Ti(Ph)]2(μ-OEt)2}(4) in ca. 9% yield. According to the crystal structure, 2 and 3 are monomeric and tetrahedral, with boat-conformation ligands. The X-ray structure of 4 showed the complex to be dimeric, with titanium in a distorted pyramidal coordination geometry. The reduction of 1 with 1.0 equiv of LiBEt3H, excess Na/Hg, or 1.0 equiv of KC8 gave the titanium(III) salts [Ti(L)2·M(THF)2] (M = Li, 5; M = Na, 6) and [Ti(L)2·K(DME)2] (7), respectively. The molecular structures of 5 and 7 were confirmed by single-crystal X-ray analysis. The titanium atom in complexes 5 and 7 is four-coordinate, with a distorted tetrahedral arrangement and the same ligand orientations as in 2−4. The lithium atom in 5 is four-coordinate with two coordinated THF molecules, while the big potassium ion in 7 is six-coordinate with two chelated DME molecules added to the two bridging oxygen atoms of the bis(phenolato) ligands

Titanium Complexes Bearing Bisaryloxy-N-heterocyclic Carbenes: Synthesis, Reactivity, and Ethylene Polymerization Study

Reaction of titanium complex [(L)TiX2(THF)] (L = {N,N′-[(5-R-3-tert-Bu-2-O−-C6H2)CH2]2 (C3H2N2)}, R = tert-Bu, La, R = Me, Lb; X = Cl, 1a, 1b; X = Br, La, 2) with 2.0 equiv of PhCH2MgCl or MeLi in diethyl ether gave dimethyl complexes [(L)Ti(CH2Ph)2] (3a, 3b) and [(L)Ti(CH3)2](4a, 4b) by salt metathesis. Dibenzyl titanium complex [(La)Ti(CH2Ph)2] (3a) absorbs dioxygen gas to afford the oxygen-insertion product [(La)Ti(OCH2Ph)2] (5) in 57% yield. The reduction of [(La)MBr2(THF)] (2) with 1 equiv of LiBEt3H in toluene gave the titanium(III) species [(La)TiBr(THF)2] (6). The molecular structures of 3b, 4b, 5, and 6 have been confirmed by X-ray single-crystal analysis. The solid state structures of these compounds reveal that these hybrid carbene ligands adopt a transoid conformation to form a pseudotrigonal-bipyramidal (for 3b, 4a, 4b, and 5) or octahedral (for 6) coordination geometry around metal centers. These titanium complexes (1, 2, and 6) showed high activities up to ca. 97 kg PE/(mol Ti·h·atm) for ethylene polymerization in the presence of MAO as coactalyst. The 13C NMR analysis revealed that linear polyethylene with low molecular weight was formed by these NHC titanium complexes. No methyl or other long-chain branch could be observed

Palladium Complexes Bearing Chiral bis(NHC) Chelating Ligands on a Spiro Scaffold: Synthesis, Characterization, and Their Application in the Oxidative Kinetic Resolution of Secondary Alcohols

A series of chiral bis-N-heterocyclic carbene ligands H2[(S)-1a–d]­X2 (X = Br, I) on a spiro scaffold and their palladium complexes (S)-2a–d and (S)-3a,b were prepared and applied in the enantioselective oxidative kinetic resolution of secondary alcohols. The corresponding alcohols can be obtained in high yields with moderate to excellent ee values

Deprotonation Attempts on Imidazolium Salt Tethered by Substituted Phenol and Construction of Its Magnesium Complex by Transmetalation

Several attempts to deprotonate the imidizolium salt 1-methyl-3-(4,6-di-tert-butyl-2-hydroxybenzyl)imidazolium bromide, H2[CO]Br (4), tethered by substituted phenol to yield anonic carbene species M[CO] (M = Li, Na) resulted in the formation of {Na[ON](THF)}2 (5) and {Li[ON](THF)}2 (6) (1-methyl-2-(4,6-di-tert-butyl-2-hydroxybenzyl)imidazole, H[ON]) after warming to room temperature from −78 °C due to 1,2-aryloxy migration. Treatment of in-situ-generated M[CO] with 1.0 equiv of MesMgBr (Mes = 2,4,6-Me3C6H2) produced a rare magnesium NHC complex, {Mg[OC](Mes)}2 (8). Both 5 and 8 have been characterized by an X-ray diffraction study

Effect of the Dihedral Angle of Biaryl-Bridged Bis(<i>N</i>‑Heterocylic Carbene) Ligands on Enantioselectivity in Pd-Catalyzed Asymmetric Aryl–Aryl Cross-Coupling

A series of new biaryl-bridged bis­(N-heterocylic carbene) palladium complexes has been synthesized and applied in asymmetric Suzuki cross-coupling of aryl halide and aryl boronic acid. X-ray crystallographic studies of square-planar palladium complexes of four of these bis­(NHC) ligands revealed that the dihedral angle of the bridging biaryl moiety depends on its identity and lies between 79.65° and 92.69°. A linear correlation between the dihedral angle in these Pd complexes and cross-coupling enantioselectivity is first reported. Moreover, larger Ccarbene–Pd–Ccarbene bite angles were found to lead to increased enantioselectivity in a first fast and then slow growing tendency

Deprotonation Attempts on Imidazolium Salt Tethered by Substituted Phenol and Construction of Its Magnesium Complex by Transmetalation

Several attempts to deprotonate the imidizolium salt 1-methyl-3-(4,6-di-tert-butyl-2-hydroxybenzyl)imidazolium bromide, H2[CO]Br (4), tethered by substituted phenol to yield anonic carbene species M[CO] (M = Li, Na) resulted in the formation of {Na[ON](THF)}2 (5) and {Li[ON](THF)}2 (6) (1-methyl-2-(4,6-di-tert-butyl-2-hydroxybenzyl)imidazole, H[ON]) after warming to room temperature from −78 °C due to 1,2-aryloxy migration. Treatment of in-situ-generated M[CO] with 1.0 equiv of MesMgBr (Mes = 2,4,6-Me3C6H2) produced a rare magnesium NHC complex, {Mg[OC](Mes)}2 (8). Both 5 and 8 have been characterized by an X-ray diffraction study