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Zafar M, Subramaniyan V, Tibika F, Tulchinsky Y. Cationic ligands - from monodentate to pincer systems. Chem Commun (Camb) 2024. [PMID: 38920056 DOI: 10.1039/d4cc01489h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/27/2024]
Abstract
For a long time, the small group of cationic ligands stood out as obscure systems within the general landscape of coordinative chemistry. However, this situation has started to change rapidly during the last decade, with more and more examples of metal-coordinated cationic species being reported. The growing interest in these systems is not only of purely academic nature, but also driven by accumulating evidence of their high catalytic utility. Overcoming the inherently poor coordinating ability of cationic species often required additional structural stabilization. In numerous cases this was realized by functionalizing them with a pair of chelating side-arms, effectively constructing a pincer-type scaffold. This comprehensive review aims to encompass all cationic ligands possessing such pincer architecture reported to date. Herein every cationic species that has ever been embedded in a pincer framework is described in terms of its electronic structure, followed by an in-depth discussion of its donor/acceptor properties, based on computational studies (DFT) and available experimental data (IR, NMR or CV). We then elaborate on how the positive charge of these ligands affects the spectroscopic and redox properties, as well as the reactivity, of their complexes, compared to those of the structurally related neutral ligands. Among other systems discussed, this review also surveys our own contribution to this field, namely, the introduction of sulfonium-based pincer ligands and their complexes, recently reported by our group.
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Affiliation(s)
- Mohammad Zafar
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
| | | | - Françoise Tibika
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
| | - Yuri Tulchinsky
- Institute of Chemistry, The Hebrew University of Jerusalem, Jerusalem 9190401, Israel.
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Oliemuller LK, Moore CE, Thomas CM. Synthesis, Characterization, and Reactivity of a (PPP) Pincer-Ligated Manganese Carbonyl Complex: Polarity Reversal Imparted by the Electrophilic Nature of a Planar Mn-P(NR 2) 2 Fragment. Inorg Chem 2023; 62:13997-14009. [PMID: 37585359 DOI: 10.1021/acs.inorgchem.3c01988] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
The bonding interactions of a synthesized pincer-ligated manganese dicarbonyl complex featuring an N-heterocyclic phosphenium (NHP+) central moiety are explored. The pincer ligand [PPP]Cl was coordinated to a manganese center using Mn(CO)5Br and 254 nm light to afford the chlorophosphine complex (PPClP)Mn(CO)2Br (2) as a mixture of halide exchange products and stereoisomers. The target dicarbonyl species (PPP)Mn(CO)2 (3) was prepared by treatment of 2 with 2 equiv of the reductant KC8. Computational investigations and analysis of structural parameters were used to elucidate multiple bonding interactions between the Mn center and the PNHP atom in 3. The generation of a product of formal H2 addition, (PPHP)Mn(CO)2H (4), was achieved through the dehydrogenation of NH3BH3, affording a 2:1 mixture of 4syn:4anti stereoisomers. The nucleophilic nature of the Mn center and the electrophilic nature of the PNHP moiety were demonstrated through hydride addition and protonation of 3 to produce K(THF)2[(PPHP)Mn(CO)2] (6) and (PPClP)Mn(CO)2H (5), respectively. The observed reactivity suggests that 3 is best described as a Mn-I/NHP+ complex, in contrast to pincer-ligated dicarbonyl manganese analogues typically assigned as MnI species.
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Affiliation(s)
- Leah K Oliemuller
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Curtis E Moore
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
| | - Christine M Thomas
- Department of Chemistry and Biochemistry, The Ohio State University, 100 West 18th Avenue, Columbus, Ohio 43210, United States
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Lee B, Pabst TP, Hierlmeier G, Chirik PJ. Exploring the Effect of Pincer Rigidity on Oxidative Addition Reactions with Cobalt(I) Complexes. Organometallics 2023; 42:708-718. [PMID: 37223209 PMCID: PMC10201995 DOI: 10.1021/acs.organomet.3c00079] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Abstract
Cobalt complexes containing the 2,6-diaminopyridine-substituted PNP pincer (iPrPNMeNP = 2,6-(iPr2PNMe)2(C5H3N)) were synthesized. A combination of solid-state structures and investigation of the cobalt(I)/(II) redox potential established a relatively rigid and electron-donating chelating ligand as compared to iPrPNP (iPrPNP = 2,6-(iPr2PCH2)2(C5H3N)). Based on a buried volume analysis, the two pincer ligands are sterically indistinguishable. Nearly planar, diamagnetic, four-coordinate complexes were observed independent of the field strength (chloride, alkyl, aryl) of the fourth ligand completing the coordination sphere of the metal. Computational studies supported a higher barrier for C-H oxidative addition, largely a result of the increased rigidity of the pincer. The increased oxidative addition barrier resulted in stabilization of (iPrPNMeNP)Co(I) complexes, enabling the characterization of the cobalt boryl and the cobalt hydride dimer by X-ray crystallography. Moreover, (iPrPNMeNP)CoMe served as an efficient precatalyst for alkene hydroboration likely because of the reduced propensity to undergo oxidative addition, demonstrating that reactivity and catalytic performance can be tuned by rigidity of pincer ligands.
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Affiliation(s)
- Boran Lee
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Tyler P Pabst
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Gabriele Hierlmeier
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
| | - Paul J Chirik
- Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States
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Narro AL, Arman HD, Tonzetich ZJ. Insertion chemistry of iron(II) boryl complexes. Dalton Trans 2022; 51:15475-15483. [PMID: 36156616 DOI: 10.1039/d2dt02879d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Iron(II) boryl complexes of the pyrrole-based pincer ligand, CyPNP (CyPNP = anion of 2,5-bis(dicyclohexylphophinomethyl)pyrrole) have been synthesized and their insertion reactivity interrogated. Compounds of the type [Fe(BE)(CyPNP)] (E = pinacholato or catecholato) can be generated by treatment of the precursors, [Fe(OPh)(py)(CyPNP)] or [FeMe(CyPNP)], with B2E2. The boryl complexes are meta stable, but permit additional reactivity with several unsaturated substrates. Reaction with alkynes, RCCR', leads to rapid insertion into the Fe-B bond to generate stable vinyl boronate complexes of the type [Fe(C{R}C{R'}BE)(CyPNP)] (R, R' = H, Me, Ph, -CCPh). Each of the compounds is five-coordinate in the solid state by virtue of coordination of one of the oxygen atoms of the boronate ester. Similar reaction with nitriles, RCN (R = Ph, Me), results in facile de-cyanation to produce the correpsonding hydrocarbon complexes, [FeR(CyPNP)]. In the case of the bulky nitrile 1-AdCN, the insertion intermediate, [Fe(C{Ad}NBpin)(CyPNP)], has been isolated and structurally characterized. Treatment of the boryl complexes with styrene derivatives results in initial insertion to give an alkylboronate complex followed by either β-H elimination or protonation to give the products of C-H borylation and hydroboration, respectively.
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Affiliation(s)
- Ana L Narro
- Department of Chemistry, University of Texas at San Antonio (UTSA), San Antonio, TX 78249, USA.
| | - Hadi D Arman
- Department of Chemistry, University of Texas at San Antonio (UTSA), San Antonio, TX 78249, USA.
| | - Zachary J Tonzetich
- Department of Chemistry, University of Texas at San Antonio (UTSA), San Antonio, TX 78249, USA.
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Hollingsworth WM, Hill EA. Exploring the potential role of heavy pnictogen elements in ligand design for new metal-ligand cooperative chemistry. J COORD CHEM 2022. [DOI: 10.1080/00958972.2022.2124863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2022]
Affiliation(s)
- W. M. Hollingsworth
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL, USA
| | - E. A. Hill
- Department of Chemistry and Biochemistry, Auburn University, Auburn, AL, USA
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Gordon BM, Lease N, Emge TJ, Hasanayn F, Goldman AS. Reactivity of Iridium Complexes of a Triphosphorus-Pincer Ligand Based on a Secondary Phosphine. Catalytic Alkane Dehydrogenation and the Origin of Extremely High Activity. J Am Chem Soc 2022; 144:4133-4146. [DOI: 10.1021/jacs.1c13309] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Benjamin M. Gordon
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Nicholas Lease
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Thomas J. Emge
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
| | - Faraj Hasanayn
- Department of Chemistry, American University of Beirut, Beirut 1107 2020, Lebanon
| | - Alan S. Goldman
- Department of Chemistry and Chemical Biology, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, United States
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Newar R, Begum W, Akhtar N, Antil N, Chauhan M, Kumar A, Gupta P, Malik J, Kumar B, Manna K. Mono‐Phosphine Metal‐Organic Framework‐Supported Cobalt Catalyst for Efficient Borylation Reactions. Eur J Inorg Chem 2022. [DOI: 10.1002/ejic.202101019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Rajashree Newar
- Indian Institute of Technology Delhi Chemistry HAUZ KHASNew Delhi 110016 New Delhi INDIA
| | - Wahida Begum
- Indian Institute of Technology Delhi Chemistry Hauz KhasNew Delhi 110016 New Delhi INDIA
| | - Naved Akhtar
- Indian Institute of Technology Delhi Chemistry HAUZ KHASNew Delhi 110016 New Delhi INDIA
| | - Neha Antil
- Indian Institute of Technology Delhi Chemistry HAUZ KHASNew Delhi 110016 New Delhi INDIA
| | - Manav Chauhan
- Indian Institute of Technology Delhi Chemistry Hauz KhasIIT DELHI, HAUZ KHAS 110016 New Delhi INDIA
| | - Ajay Kumar
- Indian Institute of Technology Delhi Chemistry HAUZ KHASNew Delhi 110016 New Delhi INDIA
| | - Poorvi Gupta
- Indian Institute of Technology Delhi Chemistry HAUZ KHAS 110016 New Delhi INDIA
| | - Jaideep Malik
- Indian Institute of Technology Roorkee Chemistry Roorkee 247667 Roorkee INDIA
| | - Balendra Kumar
- Sri Venkateswara College Chemistry University of Delhi 110021 New Delhi INDIA
| | - Kuntal Manna
- Indian Institute of Technology Delhi Department of Chemistry CHEMISTRY IIT DELHI, HAUZ KHAS 110016 New Delhi INDIA
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Bose SK, Mao L, Kuehn L, Radius U, Nekvinda J, Santos WL, Westcott SA, Steel PG, Marder TB. First-Row d-Block Element-Catalyzed Carbon-Boron Bond Formation and Related Processes. Chem Rev 2021; 121:13238-13341. [PMID: 34618418 DOI: 10.1021/acs.chemrev.1c00255] [Citation(s) in RCA: 96] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Organoboron reagents represent a unique class of compounds because of their utility in modern synthetic organic chemistry, often affording unprecedented reactivity. The transformation of the carbon-boron bond into a carbon-X (X = C, N, and O) bond in a stereocontrolled fashion has become invaluable in medicinal chemistry, agrochemistry, and natural products chemistry as well as materials science. Over the past decade, first-row d-block transition metals have become increasingly widely used as catalysts for the formation of a carbon-boron bond, a transformation traditionally catalyzed by expensive precious metals. This recent focus on alternative transition metals has enabled growth in fundamental methods in organoboron chemistry. This review surveys the current state-of-the-art in the use of first-row d-block element-based catalysts for the formation of carbon-boron bonds.
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Affiliation(s)
- Shubhankar Kumar Bose
- Centre for Nano and Material Sciences (CNMS), Jain University, Jain Global Campus, Bangalore-562112, India
| | - Lujia Mao
- Key Laboratory of Tropical Translational Medicine of Ministry of Education, Hainan Key Laboratory for Research and Development of Tropical Herbs, School of Pharmacy, Hainan Medical University, 571199 Haikou, Hainan, P. R. China
| | - Laura Kuehn
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Udo Radius
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
| | - Jan Nekvinda
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Webster L Santos
- Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Stephen A Westcott
- Department of Chemistry and Biochemistry, Mount Allison University, Sackville, NB E4L 1G8, Canada
| | - Patrick G Steel
- Department of Chemistry, University of Durham, Science Laboratories South Road, Durham DH1 3LE, U.K
| | - Todd B Marder
- Institute of Inorganic Chemistry and Institute for Sustainable Chemistry & Catalysis with Boron, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074 Würzburg, Germany
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