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Collins Rice C, Hayden JA, Hawkins AD, Morris LJ, Turner ZR, Buffet JC, O’Hare D. Trends in Structure and Ethylene Polymerization Reactivity of Transition-Metal Permethylindenyl-phenoxy (PHENI*) Complexes. Organometallics 2024; 43:540-556. [PMID: 38425384 PMCID: PMC10900520 DOI: 10.1021/acs.organomet.3c00503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 01/24/2024] [Accepted: 01/24/2024] [Indexed: 03/02/2024]
Abstract
A family of ansa-permethylindenyl-phenoxy (PHENI*) transition-metal chloride complexes has been synthesized and characterized (1-7; {(η5-C9Me6)Me(R″)Si(2-R-4-R'-C6H2O)}MCl2; R,R' = Me, tBu, Cumyl (CMe2Ph); R″ = Me, nPr, Ph; M = Ti, Zr, Hf). The ancillary chloride ligands could readily be exchanged with halides, alkyls, alkoxides, aryloxides, or amides to form PHENI* complexes [L]TiX2 (8-17; X = Br, I, Me, CH2SiMe3, CH2Ph, NMe2, OEt, ODipp). The solid-state crystal structures of these PHENI* complexes indicate that one of two conformations may be preferred, parametrized by a characteristic torsion angle (TA'), in which the η5 system is either disposed away from the metal center or toward it. Compared to indenyl PHENICS complexes, the permethylindenyl (I*) ligand appears to favor a conformation in which the metal center is more accessible. When heterogenized on solid polymethylaluminoxane (sMAO), titanium PHENI* complexes exhibit exceptional catalytic activity toward the polymerization of ethylene. Substantially greater activities are reported than for comparable PHENICS catalysts, along with the formation of ultrahigh-molecular-weight polyethylenes (UHMWPE). Catalyst-cocatalyst ion pairing effects are observed in cationization experiments and found to be significant in homogeneous catalytic regimes; these effects are also related to the influence of the ancillary ligand leaving groups in slurry-phase polymerizations. Catalytic efficiency and polyethylene molecular weight are found to increase with pressure, and PHENI* catalysts can be categorized as being among the most active for the controlled synthesis of UHMWPE.
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Affiliation(s)
- Clement
G. Collins Rice
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.
| | - Justin A. Hayden
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.
| | - Adam D. Hawkins
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.
| | - Louis J. Morris
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.
| | - Zoë R. Turner
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.
| | - Jean-Charles Buffet
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.
| | - Dermot O’Hare
- Chemistry Research Laboratory, Department
of Chemistry, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K.
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Paul A, Martins LMDRS, Karmakar A, Kuznetsov ML, C. Guedes da Silva MF, Pombeiro AJL. Zn(II)-to-Cu(II) Transmetalation in an Amide Functionalized Complex and Catalytic Applications in Styrene Oxidation and Nitroaldol Coupling. Molecules 2020; 25:E2644. [PMID: 32517273 PMCID: PMC7321079 DOI: 10.3390/molecules25112644] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 06/03/2020] [Accepted: 06/04/2020] [Indexed: 11/16/2022] Open
Abstract
The mononuclear zinc(II) complex cis-[ZnL2(H2O)2] (1; L = 4-(pyridin-3-ylcarbamoyl)benzoate) was synthesized and characterized. By soaking crystals of 1 in a mixture of DMF-H2O solution containing a slight excess of Cu(NO3)2 × 3H2O a transmetalation reaction occurred affording the related copper(II) complex trans-[CuL2(H2O)2] (2). The structures of the compounds were authenticated by single crystal X-ray diffraction revealing, apart from a change in the isomerism, an alteration in the relative orientation of the chelating carboxylate groups and of the pyridine moieties. H-bond interactions stabilize both geometries and expand them into two-dimensional (2D) networks. The transmetalation was confirmed by SEM-EDS analysis. Moreover, the thermodynamic feasibility of the transmetalation is demonstrated by density-functional theory (DFT) studies. The catalytic activities of 1 and 2 for the oxidation of styrene and for the nitroaldol (Henry) C-C coupling reaction were investigated. The copper(II) compound 2 acts as heterogeneous catalyst for the microwave-assisted oxidation of styrene with aqueous hydrogen peroxide, yielding selectively (>99%) benzaldehyde up to 66% of conversion and with a turnover frequency (TOF) of 132 h-1. The zinc(II) complex 1 is the most active catalyst (up to 87% yield) towards the nitroaldol (Henry) coupling reaction between benzaldehyde and nitro-methane or -ethane to afford the corresponding β-nitro alcohols. The reaction of benzaldehyde with nitroethane in the presence of 1 produced 2-nitro-1-phenylpropanol in the syn and the anti diastereoisomeric forms, with a considerable higher selectivity towards the former (66:34).
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Affiliation(s)
- Anup Paul
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (A.K.); (M.L.K.)
| | - Luísa M. D. R. S. Martins
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (A.K.); (M.L.K.)
| | | | | | - M. Fátima C. Guedes da Silva
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (A.K.); (M.L.K.)
| | - Armando J. L. Pombeiro
- Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa, 1049-001 Lisboa, Portugal; (A.K.); (M.L.K.)
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Helland SD, Chang AS, Lee KW, Hutchison PS, Brennessel WW, Eckenhoff WT. Synthesis and Characterization of Strongly Solvatochromic Molybdenum(III) Complexes. Inorg Chem 2020; 59:705-716. [PMID: 31860297 DOI: 10.1021/acs.inorgchem.9b02955] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A series of seven molybdenum(III) complexes with the general formula of [Mo(diimine)Cl4]- were synthesized and characterized by X-ray diffraction, IR, cyclic voltammetry (CV), and UV-vis. The complexes were discovered to be highly solvatochromic, showing shifts in λmax between ∼120 and 170 nm in solvents ranging from water to acetone. Varying the substituents on the diimine ligand influenced the absorption energy such that electron-withdrawing groups induced a red shift while electron-donating groups exhibited the opposite effect. The complexes were surprisingly stable in both acidic and basic solutions, and in the case where carboxylic acid substituents were present, additional shifts in the absorption maxima were observed, corresponding to the state of protonation of these groups. Both the MoIV/III and MoIII/II redox couples were observed in CV experiments and were complemented with density functional theory (DFT) calculations.
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Affiliation(s)
- Sarah D Helland
- Department of Chemistry , Rhodes College , 2000 North Parkway , Memphis , Tennessee 38112 , United States
| | - Alison S Chang
- Department of Chemistry , Rhodes College , 2000 North Parkway , Memphis , Tennessee 38112 , United States
| | - Keren W Lee
- Department of Chemistry , Rhodes College , 2000 North Parkway , Memphis , Tennessee 38112 , United States
| | - Phillips S Hutchison
- Department of Chemistry , Rhodes College , 2000 North Parkway , Memphis , Tennessee 38112 , United States
| | - William W Brennessel
- Department of Chemistry , University of Rochester , 120 Trustee Road , Rochester , New York 14627 , United States
| | - William T Eckenhoff
- Department of Chemistry , Rhodes College , 2000 North Parkway , Memphis , Tennessee 38112 , United States
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Ju FY, Li GL, Li XL, Yin WD, Liu GZ. Syntheses, Structures, and Properties of Two Cd(II)/Zn(II) Complexes with 1,2,4-triazole Derivatives. RUSS J COORD CHEM+ 2019. [DOI: 10.1134/s1070328419080049] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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Hwang S, Byun YM, Ryu JY, Farwa U, Begum H, Lee J, Lee S, Park HR, Lee J. Potassium coordination polymer complex containing tetrazolyl ligand. J Mol Struct 2019. [DOI: 10.1016/j.molstruc.2019.02.064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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