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Baweja S, Gabler T, Lönnecke P, Hey-Hawkins E. Metal phosphine aldehyde complexes and their application in Cu-free Sonogashira and Suzuki-Miyaura cross-coupling reactions. Dalton Trans 2023; 52:6494-6500. [PMID: 37096400 DOI: 10.1039/d3dt00507k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/26/2023]
Abstract
Transition metal coordination chemistry and catalysis are rife with phosphine ligands. One of the rather less studied members of the phosphine ligand family are phosphine aldehydes. We have synthesised 3-(diphenylphosphino)propanal (PCHO) with a slight modification of the known procedure and studied its complexation behaviour with palladium(II) and platinum(II). The catalytic activity of the palladium(II) phosphine aldehyde complexes was investigated in Cu-free Sonogashira and Suzuki-Miyaura cross-coupling reactions. Furthermore, the homogeneous nature of the catalytically active species was confirmed.
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Affiliation(s)
- Saral Baweja
- Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Leipzig University, Johannisallee 29, D-04103 Leipzig, Germany.
| | - Tom Gabler
- Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Leipzig University, Johannisallee 29, D-04103 Leipzig, Germany.
| | - Peter Lönnecke
- Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Leipzig University, Johannisallee 29, D-04103 Leipzig, Germany.
| | - Evamarie Hey-Hawkins
- Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Leipzig University, Johannisallee 29, D-04103 Leipzig, Germany.
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2
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Xing Y, Xu L, Liu S, Li Z. Dinuclear Group 4 Metal Complexes Bearing Anthracene-Bridged Bifunctional Amido-Ether Ligands: Remarkable Metal Effect and Cooperativity toward Ethylene/1-Octene Copolymerization. Inorg Chem 2023; 62:2859-2869. [PMID: 36719090 DOI: 10.1021/acs.inorgchem.2c04211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Two types of bifunctional amido-ether ligands (syn-L and anti-L) with the rigid anthracene skeleton were designed to support dinuclear group 4 metal complexes. All organic ligands and organometallic complexes (syn-M2 and anti-M2; M = Hf, Zr, and Ti) were fully characterized by 1H and 13C NMR spectroscopies and elemental analyses. The anti-Hf2 complex showed two confirmations at room temperature with C2-symmetry or S2-symmetry that can inter-exchange, as indicated by VT NMR, while only a C2-symmetric isomer was observed for syn-Hf2 complex at room temperature. However, for Zr and Ti analogues, both syn and anti complexes exhibited only one conformation at room temperature. The molecular structures of complexes syn-Hf2, anti-Hf2, and syn-Ti2 in the solid state were further determined by single-crystal X-ray diffraction, revealing the distances between two metal centers in syn-M2 from 7.138 Å (syn-Ti2) to 7.321 Å (syn-Hf2) but a much farther separation in anti-M2 (8.807 Å in C2-symmetric anti-Hf2). The mononuclear complex (2-CH3O-C6H4-N-C14H9)Zr(NMe2)3 (mono-Zr1) was also prepared for control experiments. In the presence of alkyl aluminum (AlEt3) as the alkylating agent and trityl borate ([Ph3C][B(C6F5)4]) as the co-catalyst, all metal complexes were tested for copolymerization of ethylene with 1-octene at high temperature (130 °C). The preliminary polymerization results revealed that the activity was highly dependent upon the nature of metal centers, and syn-Zr2 showed the highest activity of 9600 kg(PE)·mol-1 (Zr)·h-1, which was about 17- and 2.2-fold higher than those of syn-Hf2 and syn-Ti2, respectively. Benefitting from both steric proximity and electronical interaction of two metal centers, syn-Zr2 exhibited significant cooperativity in comparison to anti-Zr2 and mono-Zr1, with regard to activity and molecular weight and 1-octene incorporation of resultant copolymers.
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Affiliation(s)
- Yanhong Xing
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Lingling Xu
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Shaofeng Liu
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Zhibo Li
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China.,College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
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3
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Kong F, Ríos P, Hauck C, Fernández-de-Córdova FJ, Dickie DA, Habgood LG, Rodríguez A, Gunnoe TB. Ethylene Dimerization and Oligomerization Using Bis(phosphino)boryl Supported Ni Complexes. J Am Chem Soc 2023; 145:179-193. [PMID: 36542802 DOI: 10.1021/jacs.2c09471] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
We report the dimerization and oligomerization of ethylene using bis(phosphino)boryl supported Ni(II) complexes as catalyst precursors. By using alkylaluminum(III) compounds or other Lewis acid additives, Ni(II) complexes of the type (RPBP)NiBr (R = tBu or Ph) show activity for the production of butenes and higher olefins. Optimized turnover frequencies of 640 molethylene·molNi-1·s-1 for the formation of butenes with 41(1)% selectivity for 1-butene using (PhPBP)NiBr, and 68 molethylene·molNi-1·s-1 for butenes production with 87.2(3)% selectivity for 1-butene using (tBuPBP)NiBr, have been demonstrated. With methylaluminoxane as a co-catalyst and (tBuPBP)NiBr as the precatalyst, ethylene oligomerization to form C4 through C20 products was achieved, while the use of (PhPBP)NiBr as the pre-catalyst retained selectivity for C4 products. Our studies suggest that the ethylene dimerization is not initiated by Ni hydride or alkyl intermediates. Rather, our studies point to a mechanism that involves a cooperative B/Ni activation of ethylene to form a key 6-membered borametallacycle intermediate. Thus, a cooperative activation of ethylene by the Ni-B unit of the (RPBP)Ni catalysts is proposed as a key element of the Ni catalysis.
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Affiliation(s)
- Fanji Kong
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Pablo Ríos
- Department of Inorganic Chemistry CSIC and. University of Seville, Center for Innovation in Advanced Chemistry (ORFEO-CINQA), Instituto de Investigaciones Quimicas (IIQ), C/Américo Vespucio 49, Seville 41092, Spain
| | - Conner Hauck
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Francisco José Fernández-de-Córdova
- Department of Inorganic Chemistry CSIC and. University of Seville, Center for Innovation in Advanced Chemistry (ORFEO-CINQA), Instituto de Investigaciones Quimicas (IIQ), C/Américo Vespucio 49, Seville 41092, Spain
| | - Diane A Dickie
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
| | - Laurel G Habgood
- Department of Chemistry, Rollins College, Winter Park, Florida 32789, United States
| | - Amor Rodríguez
- Department of Inorganic Chemistry CSIC and. University of Seville, Center for Innovation in Advanced Chemistry (ORFEO-CINQA), Instituto de Investigaciones Quimicas (IIQ), C/Américo Vespucio 49, Seville 41092, Spain
| | - T Brent Gunnoe
- Department of Chemistry, University of Virginia, Charlottesville, Virginia 22904, United States
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4
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Dinuclear Reactivity of One Metal Exalted by the Second One. TOP ORGANOMETAL CHEM 2023. [DOI: 10.1007/3418_2022_80] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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5
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Yuan Hsu S, Murphy MC, Smolensky NT, Vogels CM, Lebel AA, Masuda JD, Boudreau LH, Jr. Morin P, Westcott SA. Iminophosphine platinum(II) complexes containing long chain aniline derivatives: synthesis, characterization, and anticancer properties. Polyhedron 2022. [DOI: 10.1016/j.poly.2022.116236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Nickel-Catalyzed Ethylene Dimerization Based on PNP(NR2)2 Ligands. Catalysts 2022. [DOI: 10.3390/catal12091008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Nickel (II) complexes stabilized by PNP(NR2)2 (L1: R = Methyl, L2: R = ethyl, L3: R = isopropyl) ligands were synthesized and characterized. A narrow range of products was observed for catalytic systems containing nickel complexes and ethyl aluminum dichloride (EADC). All exhibit considerable activity in the ethylene dimerization to produce 1-butene. Precatalyst 1 is the most conducive for ethylene dimerization, producing 83.4% C4 (1-C4 36.8%) and 103.0 × 105 g/(molNi·h) in terms of its activity under the appropriate conditions. By adjusting the conditions of the catalytic system for precatalyst 2, high C4 selectivity (88.1%) with reasonable activity (76.9 × 105 g/(molNi·h)) can be obtained. The X-ray single-crystal analysis of complexes presents mononuclear bidentate coordination at the Ni center, and the relationship between certain bite angles may also imply catalytic performance.
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Tian J, Feng W, Liu S, Li Z. Titanium Complexes Bearing
NNO‐Tridentate
Ligands: Highly Active Olefin Polymerization Catalysts with Great Control on Molecular Weight and Distribution. CHINESE J CHEM 2022. [DOI: 10.1002/cjoc.202200449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Jiliang Tian
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering Qingdao University of Science and Technology Qingdao 266042 China
| | - Wenzheng Feng
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering Qingdao University of Science and Technology Qingdao 266042 China
| | - Shaofeng Liu
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering Qingdao University of Science and Technology Qingdao 266042 China
| | - Zhibo Li
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering Qingdao University of Science and Technology Qingdao 266042 China
- College of Chemical Engineering Qingdao University of Science and Technology Qingdao 266042 China
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Radhakrishna L, Kote BS, Kunchur HS, Pandey MK, Mondal D, Balakrishna MS. 1,2,3-Triazole based ligands with phosphine and pyridine functionalities: synthesis, Pd II and Pt II chemistry and catalytic studies. Dalton Trans 2022; 51:5480-5493. [PMID: 35293924 DOI: 10.1039/d2dt00112h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
This manuscript describes the syntheses of pyridine appended triazole-based mono- and bisphosphines, [o-Ph2P(C6H4){1,2,3-N3C(Py)C(H)}] (2), [o-Br(C6H4){1,2,3-N3C(Py)C(PPh2)}] (3), [C6H5{1,2,3-N3C(Py)C(PPh2)}] (4), [Ph2P(C6H4){1,2,3-N3C(Py)C(PPh2)}] (5) and [3-Ph2P-2-{1,2,3-N3C(Ph)C(PPh2)}C5H3N] (6), their palladium and platinum chemistry and catalytic applications. These ligands upon treatment with [M(COD)Cl2] (M = Pd or Pt) yielded complexes with different coordination modes, depending on the reaction conditions. Both κ2-P,N and κ2-P,P coordination modes were observed in many of the complexes indicating the ambidentate nature of these ligands. Monophosphine 2 in the presence of a base afforded rare fused-5,6-membered PCN pincer complexes [MCl{o-Ph2P(C6H4){1,2,3-N3C(Py)C(H)}}-κ3-P,C,N] (7, M = Pd; 8, M = Pt), whereas the reactions of 4 with [M(COD)Cl2] (M = Pd, Pt) produced κ2-P,N chelate complexes [MCl2{C6H5{1,2,3-N3C(Py)C(PPh2)}-κ2-P,N}] (9, M = Pd; 10, M = Pt). Similar reactions of 5 and 6 resulted in κ2-P,P chelate complexes [MCl2{{3-Ph2P-2-{1,2,3-N3C(Ph)C(PPh2)}C5H3N}-κ2-P,P}] (11, M = Pd; 12, M = Pt) and [MCl2{3-Ph2P-2-{1,2,3-N3C(Ph)C(PPh2)}C5H3N}-κ2-P,P}] (13, M = Pd; 14, M = Pt), respectively. The palladium(II) complexes have shown excellent catalytic activity in the α-alkylation reaction of acetophenone derivatives.
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Affiliation(s)
- Latchupatula Radhakrishna
- Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Basvaraj S Kote
- Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Harish S Kunchur
- Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Madhusudan K Pandey
- Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Dipanjan Mondal
- Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
| | - Maravanji S Balakrishna
- Phosphorus Laboratory, Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400076, India.
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9
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Wang D, Zhou S, Liu Y, Kang X, Liu S, Li Z, Braunstein P. Controlling Polyethylene Molecular Weights and Distributions Using Chromium Complexes Supported by SNN-Tridentate Ligands. Macromolecules 2022. [DOI: 10.1021/acs.macromol.1c02351] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Dongqi Wang
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Shengmei Zhou
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Yongxin Liu
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Xiaohui Kang
- College of Pharmacy, Dalian Medical University, Dalian 116044, China
| | - Shaofeng Liu
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Zhibo Li
- Key Laboratory of Biobased Polymer Materials, College of Polymer Science and Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
- College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
| | - Pierre Braunstein
- Laboratoire de Chimie de Coordination, CNRS, CHIMIE UMR 7177, Université de Strasbourg, 4 rue Blaise Pascal, 67081 Cedex Strasbourg, France
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Nagy M, Fiser B, Szőri M, Vanyorek L, Viskolcz B. Optical Study of Solvatochromic Isocyanoaminoanthracene Dyes and 1,5-Diaminoanthracene. Int J Mol Sci 2022; 23:1315. [PMID: 35163239 PMCID: PMC8835764 DOI: 10.3390/ijms23031315] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Revised: 01/19/2022] [Accepted: 01/22/2022] [Indexed: 11/16/2022] Open
Abstract
Isocyanoaminoarenes (ICAAr-s) are a novel and versatile group of solvatochromic fluorophores. Despite their versatile applicability, such as antifungals, cancer drugs and analytical probes, they still represent a mostly unchartered territory among intramolecular charge-transfer (ICT) dyes. The current paper describes the preparation and detailed optical study of novel 1-isocyano-5-aminoanthrace (ICAA) and its N-methylated derivatives along with the starting 1,5-diaminoanthracene. The conversion of one of the amino groups of the diamine into an isocyano group significantly increased the polar character of the dyes, which resulted in a significant 50-70 nm (2077-2609 cm-1) redshift of the emission maximum and a broadened solvatochromic range. The fluorescence quantum yield of ICAAs is strongly influenced by the polarity of the solvent. The starting anthracene-diamine is highly fluorescent in every solvent (√f = 12-53%), while the isocyano derivatives are practically nonfluorescent in solvents more polar than dioxane. This phenomenon implies the potential application of ICAAs to probe the polarity of the medium and is favorable in practical applications, such as cell-staining, resulting in a reduced background fluorescence. The ICT character of the emission states of ICAAs are in good agreement with the computational findings presented in TD-DFT calculations and molecular electrostatic potential (MESP) isosurfaces.
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Affiliation(s)
- Miklós Nagy
- Institute of Chemistry, University of Miskolc, Miskolc-Egyetemváros, 3515 Miskolc, Hungary; (B.F.); (L.V.); (B.V.)
| | | | - Milán Szőri
- Institute of Chemistry, University of Miskolc, Miskolc-Egyetemváros, 3515 Miskolc, Hungary; (B.F.); (L.V.); (B.V.)
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11
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Lin W, Liu M, Xu L, Ma Y, Zhang L, Flisak Z, Hu X, Liang T, Sun W. Nickel(II) complexes with sterically hindered 5,6,7‐trihydroquinoline derivatives selectively dimerizing ethylene to 1‐butene. Appl Organomet Chem 2022. [DOI: 10.1002/aoc.6596] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Wenhua Lin
- School of Textiles Science and Engineering Jiangnan University Wuxi China
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry Chinese Academy of Sciences Beijing China
| | - Ming Liu
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry Chinese Academy of Sciences Beijing China
| | - Lei Xu
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry Chinese Academy of Sciences Beijing China
- College of Chemical Engineering Zhejiang University of Technology Hangzhou China
| | - Yanping Ma
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry Chinese Academy of Sciences Beijing China
| | - Liping Zhang
- School of Textiles Science and Engineering Jiangnan University Wuxi China
| | - Zygmunt Flisak
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry Chinese Academy of Sciences Beijing China
- Faculty of Chemistry University of Opole Opole Poland
| | - Xinquan Hu
- College of Chemical Engineering Zhejiang University of Technology Hangzhou China
| | - Tongling Liang
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry Chinese Academy of Sciences Beijing China
| | - Wen‐Hua Sun
- Key Laboratory of Engineering Plastics and Beijing National Laboratory for Molecular Science, Institute of Chemistry Chinese Academy of Sciences Beijing China
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12
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Tian J, Zhang X, Liu S, Li Z. Chromium Complexes Supported by NNO-Tridentate Ligands: An Unprecedent Activity with the Low Requirement of MAO. Polym Chem 2022. [DOI: 10.1039/d2py00125j] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The development of metal catalysts with high activity and thermal stability but low requirement of MAO as cocatalyst is highly desired for polyolefin industrial application. In this contribution, a series...
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13
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Petit J, Saffon-Merceron N, Magna L, Mézailles N. Synthesis of L2Ni(ORF)2 (RF = C(CF3)3) Complexes and Their Reactivity in Ethylene Oligomerization. Organometallics 2021. [DOI: 10.1021/acs.organomet.1c00575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Julien Petit
- Laboratoire Hétérochimie Fondamentale et Appliquée, UMR 5069 CNRS, Université Paul Sabatier, 118 Route de Narbonne; 31062 Toulouse, France
- IFP Energies Nouvelles Rond-point de l’échangeur de Solaize, BP3, 69360 Solaize, France
| | - Nathalie Saffon-Merceron
- Institut de Chimie de Toulouse ICT − FR2599, Université Paul Sabatier, 118 Route de Narbonne, 31062 Toulouse, France
| | - Lionel Magna
- IFP Energies Nouvelles Rond-point de l’échangeur de Solaize, BP3, 69360 Solaize, France
| | - Nicolas Mézailles
- Laboratoire Hétérochimie Fondamentale et Appliquée, UMR 5069 CNRS, Université Paul Sabatier, 118 Route de Narbonne; 31062 Toulouse, France
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Synthesis of Ethylene/1-Octene Copolymers with Ultrahigh Molecular Weights by Zr and Hf Complexes Bearing Bidentate NN Ligands with the Camphyl Linker. Catalysts 2021. [DOI: 10.3390/catal11020276] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Ultrahigh molecular weight polyethylene (UHMWPE) is a class of high-performance engineering plastics, exhibiting a unique set of properties and applications. Although many advances have been achieved in recent years, the synthesis of UHMWPE is still a great challenge. In this contribution, a series of zirconium and hafnium complexes, [2,6-(R1)2-4-R2-C6H2-N-C(camphyl)=C(camphyl)-N-2,6-(R1)2-4-R2-C6H2]MMe2(THF) (1-Zr: R1 = Me, R2 = H, M = Zr; 2-Zr: R1 = Me, R2 = Me, M = Zr; 1-Hf: R1 = Me, R2 = H, M = Hf; 2-Hf: R1 = Me, R2 = Me, M = Hf), bearing bidentate NN ligands with the bulky camphyl backbone were synthesized by the stoichiometric reactions of α-diimine ligands with MMe4 (M = Hf or Zr). All Zr and Hf metal complexes were analyzed using 1H and 13C NMR spectroscopy, and the molecular structures of complexes 1-Zr and 1-Hf were determined by single-crystal X-ray diffraction, revealing that the original α-diimine ligand was selectively reduced into the ene-diamido form and generated an 1,3-diaza-2-metallocyclopentene ring in the metal complexes. Zr complexes 1-Zr and 2-Zr showed moderate activity (up to 388 kg(PE)·mol−1(M)·h−1), poor copolymerization ability, but unprecedented molecular weight capability toward ethylene/1-octene copolymerization. Therefore, copolymers with ultrahigh molecular weights (>600 or 337 × 104 g∙mol−1) were successfully synthesized by 1-Zr or 2-Zr, respectively, with the borate cocatalyst [Ph3C][B(C6F5)4]. Surprisingly, Hf complexes 1-Hf and 2-Hf showed negligible activity under otherwise identical conditions, revealing the great influence of metal centers on catalytic performances.
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