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Khrizanforova VV, Fayzullin RR, Kartashov SV, Morozov VI, Khrizanforov MN, Gerasimova TP, Budnikova YH. Carbon Dioxide Electroreduction and Formic Acid Oxidation by Formal Nickel(I) Complexes of Di-isopropylphenyl Bis-iminoacenaphthene. Chemistry 2024; 30:e202400168. [PMID: 38380792 DOI: 10.1002/chem.202400168] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 02/20/2024] [Accepted: 02/20/2024] [Indexed: 02/22/2024]
Abstract
Processing CO2 into value-added chemicals and fuels stands as one of the most crucial tasks in addressing the global challenge of the greenhouse effect. In this study, we focused on the complex (dpp-bian)NiBr2 (where dpp-bian is di-isopropylphenyl bis-iminoacenaphthene) as a precatalyst for the electrochemical reduction of CO2 into CH4 as the sole product. Cyclic voltammetry results indicate that the realization of a catalytically effective pattern requires the three-electron reduction of (dpp-bian)NiBr2. The chemically reduced complexes [K(THF)6]+[(dpp-bian)Ni(COD)]- and [K(THF)6]+[(dpp-bian)2Ni]- were synthesized and structurally characterized. Analyzing the data from the electron paramagnetic resonance study of the complexes in solutions, along with quantum-chemical calculations, reveals that the spin density is predominantly localized at their metal centers. The superposition of trajectory maps of the electron density gradient vector field∇ ρ r ${\nabla \rho \left({\bf r}\right)}$ and the electrostatic force density fieldF e s r ${{{\bf F}}_{{\rm e}{\rm s}}\left({\bf r}\right)}$ per electron, as well as the atomic charges, discloses that, within the first coordination sphere, the interatomic charge transfer occurs from the metal atom to the ligand atoms and that the complex anions can thus be formally described by the general formulae (dpp-bian)2-Ni+(COD) and (dpp-bian)2 -Ni+. It was also shown that the reduced nickel complexes can be oxidized by formic acid; resulting from this reaction, the two-electron and two-proton addition product dpp-bian-2H is formed.
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Affiliation(s)
- Vera V Khrizanforova
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, 8 Arbuzov Street, Kazan, 420088, Russian Federation
| | - Robert R Fayzullin
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, 8 Arbuzov Street, Kazan, 420088, Russian Federation
| | - Sergey V Kartashov
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, 8 Arbuzov Street, Kazan, 420088, Russian Federation
| | - Vladimir I Morozov
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, 8 Arbuzov Street, Kazan, 420088, Russian Federation
| | - Mikhail N Khrizanforov
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, 8 Arbuzov Street, Kazan, 420088, Russian Federation
| | - Tatiana P Gerasimova
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, 8 Arbuzov Street, Kazan, 420088, Russian Federation
| | - Yulia H Budnikova
- Arbuzov Institute of Organic and Physical Chemistry, FRC Kazan Scientific Center, Russian Academy of Sciences, 8 Arbuzov Street, Kazan, 420088, Russian Federation
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Varga V, Pokorná K, Lamač M, Horáček M, Pinkas J. Preparation of silyl-terminated branched polyethylenes catalyzed by Brookhart's nickel diimine complex activated with hydrosilane/B(C 6F 5) 3. Dalton Trans 2024; 53:5249-5257. [PMID: 38406967 DOI: 10.1039/d3dt04200f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2024]
Abstract
Brookhart's nickel α-diimine complex [(κ2-N,N-BIAN)NiCl2] (1) (where BIAN = {Ar-NAceN-Ar}, Ace = acenaphthen-1,2-diyl, and Ar = 2,6-(iPr)2-C6H3) activated with a hydrosilane/B(C6F5)3 (SiHB) adduct forms a highly active catalytic system for ethylene polymerization. Under optimal conditions, the activity of the system depends on the nature of hydrosilane and decreases in the order R3SiH > Ph2SiH2 > PhSiH3. The decrease in system activity within the hydrosilane series is correlated with increasing formation of Ni(I) species. In addition to their activation effect, hydrosilanes act as efficient chain termination/chain transfer agents, with the Si/Ni ratio controlling the molecular weight of the resulting polyethylene (PE). The use of Et3SiH generated elastomeric, highly branched polymers with a saturated chain-end, while systems using Ph2SiH2 and PhSiH3 led to branched end-functionalized PEs terminated with the hydrosilyl functionality (i.e. br-PE-SiPh2H or br-PE-SiPhH2).
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Affiliation(s)
- Vojtech Varga
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.
| | - Kristýna Pokorná
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.
| | - Martin Lamač
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.
| | - Michal Horáček
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.
| | - Jiří Pinkas
- J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i., Dolejškova 3, 182 23 Prague 8, Czech Republic.
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New Ni(II)-Ni(II) Dinuclear Complex, a Resting State of the (α-diimine)NiBr2/AlMe3 Catalyst System for Ethylene Polymerization. Catalysts 2023. [DOI: 10.3390/catal13020333] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
A novel room-temperature stable diamagnetic nickel complex 2 was detected upon activation of Brookhart-type ethylene polymerization pre-catalyst LNiBr2 (1, L = 1,4-bis-2,4,6-trimethylphenyl-2,3-dimethyl-1,4-diazabuta-1,3-diene) with AlMe3. Using in situ 1H, 2H, and 13C NMR spectroscopy, as well as DFT calculations, this species has been identified as an antiferromagnetically coupled homodinuclear complex [LNiII(μ-Me)(μ-CH2)NiIIL]+Br−. Its behavior in the reaction solution is characteristic of the resting state of nickel catalyzed ethylene polymerization.
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Soshnikov IE, Semikolenova NV, Bryliakov KP, Antonov AA, Talsi EP. Ni(I) Intermediates Formed upon Activation of a Ni(II) α-Diimine Ethylene Polymerization Precatalyst with AlR 3 (R = Me, Et, and iBu), AlR 2Cl (R = Me, Et), and MMAO: A Comparative Study. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00065] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Igor E. Soshnikov
- Boreskov Institute of Catalysis, Pr. Lavrentieva, 5, 630090, Novosibirsk, Russian Federation
| | - Nina V. Semikolenova
- Boreskov Institute of Catalysis, Pr. Lavrentieva, 5, 630090, Novosibirsk, Russian Federation
| | - Konstantin P. Bryliakov
- Boreskov Institute of Catalysis, Pr. Lavrentieva, 5, 630090, Novosibirsk, Russian Federation
| | - Artem A. Antonov
- Boreskov Institute of Catalysis, Pr. Lavrentieva, 5, 630090, Novosibirsk, Russian Federation
| | - Evgenii P. Talsi
- Boreskov Institute of Catalysis, Pr. Lavrentieva, 5, 630090, Novosibirsk, Russian Federation
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Abstract
Nickel(II) complexes with bidentate N,N-α-diimine ligands constitute a broad class of promising catalysts for the synthesis of branched polyethylenes via ethylene homopolymerization. Despite extensive studies devoted to the rational design of new Ni(II) α-diimines with desired catalytic properties, the polymerization mechanism has not been fully rationalized. In contrast to the well-characterized cationic Ni(II) active sites of ethylene polymerization and their precursors, the structure and role of Ni(I) species in the polymerization process continues to be a “black box”. This perspective discusses recent advances in the understanding of the nature and role of monovalent nickel complexes formed in Ni(II) α-diimine-based ethylene polymerization catalyst systems.
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