Anilido-imine Ligands Research Articles

Copper Complexes with N,N,N-Tridentate Quinolinyl Anilido-Imine Ligands: Synthesis and Their Catalytic Application in Chan-Lam Reactions.

The treatment of 2-(ArNC(H))C6H4-HNC9H6N with n-BuLi and the subsequent addition of CuCl2 afforded the anilido-aldimine Cu(II) complexes 1-5 Cu[{2-[ArN=C(H)]C6H4}N(8-C9H6N)]Cl (Ar = 2,6-iPr2C6H3 (1), 2,4,6-(CH3)3C6H2 (2), 4-OCH3C6H4 (3), 4-BrC6H4 (4), 4-ClC6H4 (5)), respectively. All the copper complexes were fully characterized by IR, EPR and HR-MS spectra. The X-ray diffraction analysis reveals that 2 and 4 are mononuclear complexes, and the Cu atom is sitting in a slightly square-planar geometry. These Cu(II) complexes have exhibited excellent catalytic activity in the Chan-Lam coupling reactions of benzimidazole derivatives with arylboronic acids, achieving the highest yields of up to 96%.

Nickel complexes bearing N,N,N-tridentate quinolinyl anilido-imine ligands: Synthesis, characterization and catalysis in Suzuki-Miyaura cross-coupling reaction

Four nickel complexes incorporating N,N,N-quinolinyl anilido-imine ligands based on ortho-C6H4F(CH = NAr) and 8-aminoquinoline, Ni[{2-[ArN = C(H)]C6H4}N(8-C9H6N)]Br (Ar = 2,6-iPr2C6H3 (1a), 2,4,6-(CH3)3C6H2 (1b), 4-BrC6H4 (1c)) and Ni[{2-[ArN = C(H)]C6H4}N(8-C9H6N)]2 (Ar = 4-ClC6H4 (1d)) were synthesized and structurally characterized by HR-MS, IR, NMR spectroscopy and X-ray crystallography. These nickel(II) complexes were used in Suzuki-Miyaura coupling and exhibited moderate to excellent catalytic activity with a low catalyst loading of 2.0 mol%.

Side-Arm Assisted Anilido-Imine Based Rare-Earth Metal Complexes for Isoprene Stereoselective Polymerization.

Anilido-imine ligands o-C6H4(NHAr1)(CH=NAr2), in which Ar1 is 2,6-diisopropylbenzyl group and Ar2 contains fluorine (HL1) or methoxyl (HL2) group on ortho-position of phenyl substituent, were synthesized for constructing rare-earth metals based complexes of 1a–1c (HL1 based Sc, Lu, Y) and 2a–2c (HL2 based Sc, Lu, Y). Based on their NMR spectra and X-ray single-crystal structures, the side-arm group of -F and -OMe is identified to chelate to the corresponding central metal. The twisted angles between two planes formed by chelated heteroatoms (N, N, F for HL1 and N, N, O for HL2) are observed, in which the largest dihedral angle (53.3°) for HL1-Y and the smallest dihedral angle (44.32°) for HL2-Sc are detected. After being activated by AliBu3 and [Ph3C][B(C6F5)4], these catalysts showed great activity for isoprene polymerization. Bearing the same ligand HL1, smaller scandium based complex 1a and middle size of lutetium based 1b provided lower cis-1,4-selectivity (57.3% and 64.2%), larger yttrium complex 1c displayed high cis-1,4-selectivity (84%). Chelating by crowded HL2, small size of scandium complex 2a provided impressive trans-1,4-selectivity (93.0%), middle lutetium based 2b displayed non-selectivity and larger yttrium complex 2c showed clear cis-1,4-selectivity (83.3%). Moreover, 2a/AliBu3 system showed the quasi-living chain transfer capability.

Frustrated Lewis Pair Chemistry with Magnesium Lewis Acids

Anilido imine–magnesium bromide complexes, (LHMgBr)2 and (LMeMgBr)2, have been prepared [LH = DIPP‐N(C6H4)C(H)N‐DIPP and LMe = DIPP‐N(C6H4)C(Me)N‐DIPP (DIPP = 2,6‐iPr2C6H3)]. Their dimeric crystal structures are compared to the dimer (DIPP‐nacnacMgBr)2 [DIPP‐nacnac = DIPP‐NC(Me)C(H)C(Me)N‐DIPP]. The anilido imine ligands show some degree of charge delocalization but are clearly more asymmetric than the DIPP‐nacnac complex: one of the N atoms has considerable anilido character, whereas the other one is close to an imine. Calculated natural population analysis (NPA) charges (B3PW91/6‐311++G**) and an atoms‐in‐molecules (AIM) study on model systems quantify the asymmetry in charge distribution. Quantification of the Lewis acidity of LHMgBr and LMeMgBr by the Gutmann–Beckett test gave acceptor numbers of 58.9 and 58.3, respectively. The complexes themselves are inert to a number of electrophiles; however, in combination with PPh3 the substrate 1‐butene oxide was ring‐opened. The resulting betaine‐type alkoxide complex is unstable and decomposes at room temperature through a Wittig‐type reaction. At higher temperatures also a reverse Wittig‐type decomposition is observed.

Cu(II) complexes with anilido-imine ligands: Synthesis, characterization and catalysis on reverse atom transfer radical polymerization of styrene

Several copper(II) complexes bearing bidentate anilido-imine ligands [(Ar′NCHC6H4-NAr)Cu]2(μ-Cl)2 (Ar=Ar′=2,6-Me2C6H3 (1a); Ar=Ar′=2,6-Et2C6H3 (1b); Ar=3,5-(CF3)2C6H3, Ar′=2,6-iPr2C6H3 (1d); Ar=p-OMeC6H4, Ar′=2,6-iPr2C6H3 (1e)), (Ar′NCHC6H4-NAr)CuCl (Ar=Ar′=2,6-iPr2C6H3 (1c)), and that bearing tridentate quinolinyl anilido-imine ligand (2,6-iPr2C6H3NCHC6H4-NAr)CuCl (Ar=8-quinolinyl (1f)) were synthesized via reactions of the corresponding ligands with nBuLi and subsequent in-situ addition of CuCl2. The X-ray diffraction analysis revealed that 1a and 1d are dinuclear, while 1f with N,N,N-tridentate ligand is in monomeric form. In the presence of 2,2′-azobisisobutyronitrile (AIBN), these well-defined complexes showed moderate to high activities in reverse ATRP of styrene. High conversions up to 86.5% were obtained and polymers with controllable molecular weight and relatively narrow polydispersity were produced.

Chromium Complexes with N,N,N-Tridentate Quinolinyl Anilido-Imine Ligand: Synthesis, Characterization, and Catalysis in Ethylene Polymerization

The treatment of 2-(ArN═CH)C6H4-HNC9H6N ([NQNANIMe]H, Ar = 2,6-Me2C6H3; [NQNANIEt]H, Ar = 2,6-Et2C6H3; [NQNANIiPr]H, Ar = 2,6-iPr2C6H3) with nBuLi and CrCl3(THF)3 achieves the hetero-dinuclear complexes [NQNANIR]CrCl(μ-Cl)2Li(THF)2 (1a, R = Me; 1b, R = Et; 1c, R = iPr) or bisligated complex κ5-[NQNANIiPr]2CrCl (2c) depending on the reactant ratios used. Reactions of these ligands with nBuLi and CrCl2(THF)2 could achieve the square-pyramidal complexes [NQNANIR]CrCl(THF) (3b, R = Et; 3c, R = iPr). Complex 3c can be oxidized by alkyl chloride to dimeric complex {[NQNANIiPr]CrCl}2(μ-Cl)2 (4) through a single-electron-transfer mechanism. Similar reaction of 2-(C9H6N)N═CHC6H4-HNAr ([NQNINAMe]H, Ar = 2,6-Me2C6H3; [NQNINAEt]H, Ar = 2,6-Et2C6H3; [NQNINAiPr]H, Ar = 2,6-iPr2C6H3) with nBuLi and CrCl3(THF)3 furnishes [NQNINAR]CrCl(μ-Cl)2Li(THF)2 (5a, R = Me; 5b, R = Et; 5c, R = iPr) in high yields. However, a chromium complex with a butyl-substituted ligand, [NQBuNINAiPr]CrCl2 (6), is obtained when 2 equiv of nBuLi is used. The molecular structures of 1c, 2c, 3c, 4, 5c, and 6 are confirmed by X-ray crystallography. Upon activation with MAO, the Cr(III) complexes (1a–1c, 4, and 5a–5c) show moderate catalytic activities (50 to 218 kg of PE·mol(Cr)−1·h–1) in ethylene polymerization, whereas the Cr(II) complexes 2c, 3b, and 3c are inert under the same conditions.

Iron(II) complexes bearing anilido-imine ligands: Synthesis and catalysis on ATRP of methyl methacrylate

Reactions of the ortho-C6H4(NHAr)-(CHNAr) with nBuLi and subsequent addition of FeCl2 afford the anilido-aldimine Fe(II) complexes [(ArNCHC6H4-NAr)Fe]2(μ-Cl)2 (Ar=2,6-Me2C6H3 (1a); Ar=2,6-Et2C6H3 (1b)), and (ArNCHC6H4-NAr)Fe(μ-Cl)2Li(THF)2 (Ar=2,6-iPr2C6H3 (1c)). Similarly, reactions of the 2-(ArNC(H))C6H4-HNC9H6N with nBuLi and FeCl2 give the N,N,N-tridentate iron complexes {[2-(ArNC(H))C6H4-NC9H6N]Fe}2(μ-Cl)2 (Ar=2,6-Me2C6H3 (2a), 2,6-Et2C6H3 (2b), and 2,6-iPr2C6H3 (2c)). The X-ray diffraction analysis reveals that 1a and 1b are dimeric complexes and 1c is hetero-binuclear complex. Fe(II) atoms in these complexes are all in a distorted tetrahedral geometry. Complex 2c was confirmed to be a dimeric complex with the iron atom in a trigonal bipyramidal geometry. Complexes 1a–1c show moderate activities in ATRP of MMA in the presence of benzyl chloride (BnCl). While complexes 2a–2c are inert under the same condition.

Nickel complexes bearing N,N,N-tridentate quinolinyl anilido–imine ligands: Synthesis, characterization and catalysis on norbornene addition polymerization

The N,N,N-tridentate quinolinyl anilido–imine ligands 2-(ArNC(H))C6H4–HNC9H6N (LaH, Ar = 2,6-Me2C6H3; LbH, Ar = 2,6-iPr2C6H3) and 2-(C9H6N)NC(H)C6H4–HNAr (LcH, Ar = 2,6-Me2C6H3; LdH, Ar = 2,6-iPr2C6H3) were synthesized and characterized. Reactions of these ligands with nBuLi and subsequent additions of NiCl2(DME) afford the N,N,N-tridentate nickel complexes [2-(ArNC(H))C6H4–NC9H6N]NiCl (Ar = 2,6-Me2C6H3 (1a), 2,6-iPr2C6H3 (1b)) and [2-(C9H6N)NC(H)C6H4–NAr]NiCl (Ar = 2,6-Me2C6H3 (2a), 2,6-iPr2C6H3 (2b)). All the complexes were fully characterized by NMR and elemental analyses. X-ray diffraction analyses of 1b and 2b revealed an almost square-planar geometry around the metal center. When activated with MAO, these nickel complexes can be used as catalysts for the vinyl addition polymerization of norbornene affording high molecular weight polymer.

Efficient Synthesis of Titanium Complexes Bearing Tridentate [N–,N,O–] Anilido-Imine Ligands and Their Catalytic Properties for Ethylene Polymerization

A series of tridentate anilido-imine [N,N,O] ligands 2-(2-(R12-2,6-C6H3NH)C6H4)HC═N(4-tBu-6-R2-C6H2OH) [R1 = Me, R2 = tBu (LaH2); R1 = Et, R2 = tBu (LbH2); R1 = iPr, R2 = tBu (LcH2); R1 = Me, R2 = Ad (LdH2); R1 = Et, R2 = Ad (LeH2); R1 = iPr, R2 = Ad (LfH2)] were synthesized and characterized. Reaction of the free ligand LdH2 with TiCl4 in toluene at low temperature affords the zwitterionic complex Ld+H2Ti–Cl4 (1d). The zwitterionic complex can be dissolved in THF to form THF-solvated complex 1d′. Heating 1d in toluene at 40 °C affords the neutral complex LdHTiCl3 (2d) by losing a HCl. Complex 2d can be fully converted to the final complex LdTiCl2 (3d) at 140 °C under vacuum by losing another HCl. Complexes 3a–3c, 3e, and 3f were also synthesized in high yields in the same one-pot procedure. All complexes were characterized by 1H and 13C NMR spectroscopy, and the molecular structures of 1d′, 3b, 3d, and 3e were determined by single-crystal X-ray diffraction analysis. The titanium centers in complexes 3b, ...

Al and Zn complexes bearing N,N,N-tridentate quinolinyl anilido-imine ligands: synthesis, characterization and catalysis in l-lactide polymerization

Reactions of N,N,N-tridentate quinolinyl anilido-imine ligands with AlMe(3) afford mononuclear aluminum complexes {κ(3)-[{2-[ArN=C(H)]C(6)H(4)}N(8-C(9)H(6)N)]}AlMe(2) (Ar = 2,6-Me(2)C(6)H(3) (1a), 2,6-Et(2)C(6)H(3) (1b), 2,6-(i)Pr(2)C(6)H(3) (1c)) or dinuclear complexes AlMe(3){κ(1)-[{2-[ArN=C(H)C(6)H(4)]N(8-C(9)H(6)N)}-κ(2)]AlMe(2) (R = 2,6-Me(2)C(6)H(3) (2a), 2,6-Et(2)C(6)H(3) (2b), 2,6-(i)Pr(2)C(6)H(3) (2c)) depending on the ratios of reactants used. Similar reactions of ZnEt(2) with these ligands give the monoligated ethyl zinc complexes {κ(3)-[{2-[ArN=C(H)]C(6)H(4)}N(8-C(9)H(6)N)]}ZnEt (Ar = 2,6-Me(2)C(6)H(3) (3a), 2,6-Et(2)C(6)H(3) (3b), 2,6-(i)Pr(2)C(6)H(3) (3c)) or bisligated complexes {κ(3)-[{2-[ArN=C(H)]C(6)H(4)}N(8-C(9)H(6)N)]}Zn{κ(2)-[{2-[ArN=C(H)]C(6)H(4)}N(8-C(9)H(6)N)]} (Ar = 2,6-Me(2)C(6)H(3) (4a), 2,6-Et(2)C(6)H(3) (4b), 2,6-(i)Pr(2)C(6)H(3) (4c)). These complexes were well characterized by NMR and the structures of 1a, 2a, 2c, 3b and 4c were confirmed by X-ray diffraction analysis. The aluminum and zinc complexes were tested to initiate lactide polymerization in which the zinc complexes show moderate to high activities in the presence of benzyl alcohol.

Chromium(III) Complexes with Chelating Anilido–Imine Ligands: Synthesis, Structures, and Catalytic Properties for Ethylene Polymerization

AbstractA series of novel chromium complexes that bear anilido–imine ligands, [{ortho‐C6H4(NAr′)(CH=NAr″)}CrCl2(thf)2] [Ar′ = Ar″ = C6H5 (1); Ar′ = Ar″ = p‐MeC6H4 (2); Ar′ = Ar″ = 2,6‐Me2C6H3 (3); Ar′ = 2,6‐iPr2C6H3, Ar″ = 2,6‐Me2C6H3 (4); Ar′ = Ar″ = 2,6‐iPr2C6H3 (5)], have been synthesized and characterized by elemental analysis, IR spectroscopy, and ESI‐MS. The molecular structures of complexes 1 and 2 have been confirmed by single‐crystal X‐ray diffraction analysis. When activated with methylaluminoxane (MAO), these complexes exhibit reasonable to good catalytic activity for ethylene polymerization and produce polyethylene with moderate molecular weights.

Molecular structures of three coordinate zinc and cadmium complexes that feature β-diketiminato and anilido-imine ligands

A series of zinc and cadmium complexes of the β-diketiminato and anilido-imine classes of ligands, namely [BDI Ar], [AI Ar] and [ AI Ar,NPr 2 i ], have been synthesized and structurally characterized by X-ray diffraction. For example, the zinc and cadmium alkyl compounds [AI Ar]ZnEt and [AI Ar]CdMe have been synthesized via the reactions of [AI Ar]H with Et 2Zn and Me 2Cd, respectively, while [AI Ar]ZnN(SiMe 3) 2 has been obtained by treatment of [AI Ar]H with Zn[N(SiMe 3) 2] 2. Single crystal X-ray diffraction studies establish that the metal centers in each of these complexes are trigonal planar. Comparison of the molecular structures of [AI Ar]CdMe and [BDI Ar]CdMe demonstrates that the cadmium methyl moiety lies in the plane of the annulated [AI Ar] ligand, whereas there is considerable displacement for [BDI Ar]CdMe. [ AI Ar,NPr 2 i ]Li, an anilido-imine ligand that incorporates a CH 2 CH 2 NPr 2 i tether, has been synthesized via a sequence involving condensation of 2-fluorobenzaldehyde with H 2 NCH 2 CH 2 NPr 2 i , followed by treatment with ArNHLi. X-ray diffraction demonstrates that the lithium has a T-shaped coordination environment which is supplemented by an agostic interaction with a C–H bond of one of the isopropyl groups of the NPr 2 i moiety. However, while the NPr 2 i group of the tether coordinates to lithium in [ AI Ar,NPr 2 i ]Li, it does not coordinate to the zinc center of [ AI Ar,NPr 2 i ]ZnMe. The structure of [ AI Ar,NPr 2 i ]ZnMe is also in marked contrast to that reported for [ AI Ar , NMe 2 ]ZnMe, in which the NMe 2 group does coordinate to the zinc center. The M–C bonds of [ AI Ar,NPr 2 i ]ZnMe, [BDI Ar]ZnEt and [BDI Ar]CdMe are cleaved by B(C 6F 5) 3 to give the perfluorophenyl derivatives [ AI Ar,NPr 2 i ]ZnC 6F 5, [BDI Ar]ZnC 6F 5 and [BDI Ar]CdC 6F 5. Interestingly, the C 6F 5 groups are almost orthogonal to the planes of the chelating ligands in the zinc complexes, [ AI Ar,NPr 2 i ]ZnC 6F 5 and [BDI Ar]ZnC 6F 5, whereas the C 6F 5 and [BDI Ar] ligands of [BDI Ar]CdC 6F 5 reside in the same plane. In addition to 1:1 [ AI Ar,NPr 2 i ]ZnX complexes, it is also possible to synthesize the 2:1 complex [ AI Ar,NPr 2 i ] 2Zn which is consistent with the [ AI Ar,NPr 2 i ] ligand being less sterically demanding than the [BDI Ar] ligand.

Synthesis, structures, photoluminescent and electroluminescent properties of boron complexes with anilido-imine ligands

Abstract Syntheses of three new N-arylanilido-arylimine bidentate Schiff base type ligand precursors, ortho-C6H4[NH(2,6-iPr2C6H3)](CH NAr1) [Ar1 = p-FC6H4 (2a); C6H5 (2b); p-OMeC6H4 (2c)], and their four-coordinated boron complexes, ortho-C6H4[N(2,6-iPr2C6H3)](CH NAr1)BF2 [Ar1 = p-FC6H4 (3a); C6H5 (3b); p-OMeC6H4 (3c)] are described. The boron complexes 3a–3c were synthesized from the reaction of BF3(OEt2) with the lithium salt of their corresponding ligand. All complexes were characterized by 1H and 13C NMR spectroscopy and molecular structures of complexes 3a and 3c were determined by X-ray crystallography. The photophysical properties of complexes 3a–3c were briefly examined. All three complexes display bright green fluorescence in solution and in the solid state. Electroluminescent devices with complex 3c as the emitter were fabricated. These devices were found to give green emission with maximum current efficiency of 2.92 cd/A and maximum luminance of 670 cd/m2.

Nickel and palladium complexes bearing ortho-phenoxy modified anilido-imine ligands: Drastic steric effect on coordinated geometry, and catalytic property toward olefin polymerization

A series of new nickel complexes and palladium complexes bearing ortho-phenoxy modified anilido-imine ligands have been synthesized and characterized. X-ray diffraction analyses of the single crystal structures reveal that there are no direct metal–O interactions in all of the complexes. The steric hindrance of complexes has an importance influence on their coordinated geometries. The bulky complexes with 2,6-diisopropylphenyl substituent exist as a dimers with bromine-bridged structure while those with 2,6-dimethylphenyl or phenyl substituents adopt a distorted tetrahedral geometry with four nitrogen atoms of two anilido-imine ligands. The nickel complexes exhibited high activity up to 7.33 × 10 6 g/(mol of Ni · h) and palladium complexes showed very high activity up to 2.63 × 10 8 g/(mol of Pd · h) for norbornene polymerization with methylaluminoxane as cocatalyst. The nickel catalysts were attempted to polymerize ethylene at atmosphere pressure, however, only oligomers were produced.

Germylenes and Stannylenes with Chelating Anilido–Imine Ligands: Syntheses, Structures and Reactivity

AbstractGermylenes and stannylenes with anilido–imine ligands were synthesized in high yields by the reaction of group 14 dichlorides (Cl2Ge·dioxane, Cl2Sn) and the lithium salts of the ligands. Complexes were characterized by 1H and 13C NMR spectroscopy, and the molecular structure of methoxygermylene was determined by X‐ray crystallography. These data indicate the formation of N,N′‐chelate complexes having three‐coordinate germanium or tin atoms and quasiplanar six‐membered heterocycles. In the germanium series, cycloaddition reactions with o‐quinone were performed, and the structures of the cycloadducts were determined by X‐ray structure analyses. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Rare-Earth Metal Bis(alkyl)s Supported by a Quinolinyl Anilido-Imine Ligand: Synthesis and Catalysis on Living Polymerization of ε-Caprolactone

The tridentate ligand N-(2-((2,6-diisopropylphenylimino)methyl)phenyl)quinolin-8-amine (HL) was prepared. Treatment of HL with 1 equiv of Ln(CH2SiMe3)3(THF)2 afforded the corresponding rare-earth metal bis(alkyl) complexes LLn(CH2SiMe3)2(THF)n (Ln = Sc, n = 0 (1); Y, n = 1 (2); Lu, n = 0 (3)) in high yields. Variable-temperature 1H NMR spectral analysis showed that these complexes were fluxional at room temperature. Complexes 1 and 3 were THF-free, where the metal center adopted a square-pyramidal geometry, while in 2 the metal center generated a distorted octahedral geometry owing to the coordination of a THF molecule. All these complexes catalyzed the ring-opening polymerization of ε-caprolactone with high activities in living fashion, among which the Lu complex was proved to be more active than its Sc and Y analogues.

Synthesis, structure and electroluminescent properties of Schiff-base boron complex with anilido-imine ligand

The Schiff-base ligand boron complex, LBF 2 [L= ortho-C 6H 4(NC 6H 3Me 2-2,6)(CH=NC 6H 3Me 2-2,6)], is synthesized and characterized. The crystal structural study reveals that central boron atom is four coordinate and adopts a distorted tetrahedral geometry in LBF 2. The photo/electroluminescent properties of the boron complex have been studied. The electroluminescent devices were fabricated by doping LBF 2 in polymer blends host of poly(vinylcarbazole) (PVK) and 2- tert-butylphenyl-5-biphenyl-1,3,4-oxadiazol (PBD) using simple solution spin-coating technique. The single-layer polymer organic light emitter devices exhibited blue-green emission with maximum current efficiency of 1.6 cd/A and maximum luminance of 840 cd/m 2.

Synthesis and Characterization of NiII and PdII Complexes Bearing N,N,S Tridentate Ligands and Their Catalytic Properties for Norbornene Polymerization

AbstractA series of new N,N,S tridentate nickel(II) complexes [(ArN = CHC6H4NPh‐2‐SPh)NiBr] (Ar = 2,6‐diisopropylphenyl, 1; Ar = 2,6‐dimethylphenyl, 2; Ar = Ph, 3) and palladium(II) complexes [(ArN = CHC6H4NPh‐2‐SPh)PdCH3] (Ar = 2,6‐diisopropylphenyl, 4; Ar = 2,6‐dimethylphenyl, 5; Ar = Ph, 6) were synthesized and characterized. X‐ray diffraction analyses of the single‐crystal structures revealed that tridentate complexes 1, 2, 4, 5, and 6 featured a distorted square‐planar coordination of the central metal. Compared to the bidentate metal complexes bearing anilido–imine ligands, the N,N,S tridentate metal complexes showed better stability. In the presence of methylaluminoxane (MAO), nickel complexes 1–3 showed moderate activity toward ethylene oligomerization at atmosphere pressure, but the palladium complexes were inactive. However, the nickel complexes exhibited high activity up to 8.20 × 106 g/(mol of Ni) h and palladium complexes showed very high activity up to 2.68 × 108 g/(mol of Pd) h toward norbornene polymerization with MAO as cocatalyst. The obtained polynorbornenes are vinylic addition polymers with high molecular weights. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Syntheses and molecular structures of 18/16-electron half-sandwich iridium(III) complexes with chelating anilido-imine ligands

A 18-electron complex Cp ∗IrCl[ o-C 6H 4N(C 6H 3-Me- p) (CH NC 6H 3-Me- p)] (Cp ∗ = η 5-pentamethylcyclopentadienyl) ( 1a) was obtained by the reaction of the lithium salt of o-C 6H 4N (C 6H 3-Me- p)(CH NHC 6H 3-Me- p) ( L 1) with [Cp ∗IrCl(μ-Cl)] 2 in toluene. However, when bulkier ligands ( L 2 = o-C 6H 4N(C 6H 3-Me- p)(CH NHC 6H 3- i-Me 2-2,6), L 3 = o-C 6H 4N(C 6H 3-Me- p) (CH NHC 6H 3- i-Pr 2-2,6)) were employed in the same reaction, two 16-electron complexes {Cp ∗Ir[ o-C 6H 4N(C 6H 3-Me- p)(CH NC 6H 3- i-Me 2-2,6)]} +Cl − ( 2b) and {Cp ∗Ir[ o-C 6H 4N(C 6H 3-Me- p)(CH NC 6H 3- i-Pr 2-2,6)]} +Cl − ( 3b) were formed. A 16-electron complex {Cp ∗Ir [ o-C 6H 4N(C 6H 3-Me- p) (CH NC 6H 3-Me- p)]} +SO 3 CF − 3 ( 1b) bearing L 1 could be achieved by the reaction of 1a with AgSO 3CF 3 in CH 3CN solution. The molecular structures of 1a and 2b were determined by X-ray crystallography. Theoretical calculations of all the 18/16-electron species were performed to study their bonding characters and electronic properties. Electron donating effect of Cp ∗ and steric effect of anilido-imine ligand were considered as major factors in the formation of coordinative unsaturated complexes 1b, 2b, 3b.

Vinyl polymerization of norbornene with nickel catalysts bearing [ N, N] six-membered chelate ring: Important influence of ligand structure on activity

Norbornene polymerizations with nickel complexes bearing [ N, N] six-membered chelate ring activated with methylaluminoxane were investigated. The influence of ligand structure such as β-diimine, β-diketiminate, fluorinated β-diketiminate, and anilido-imine ligand on catalytic activities for norbornene polymerization was evaluated in detail. Ligands led to different electrophilicity of the nickel metal center, and a relatively positive nickel metal center would result in high catalytic activities for norbornene polymerization. The influences of polymerization temperature and Al/Ni ratio on norbornene polymerization with nickel catalysts bearing β-diimine, β-diketiminate, and fluorinated β-diketiminate ligands were also examined. All of the obtained polymers catalyzed by these nickel catalysts bearing [ N, N] ligand are vinylic addition polynorbornenes with different molecular weights.