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Manca L, Senzacqua G, Stoccoro S, Zucca A. Regioselective C(sp 2)-C(sp 3) Coupling Mediated by Classical and Rollover Cyclometalation. Molecules 2024; 29:707. [PMID: 38338451 PMCID: PMC10856536 DOI: 10.3390/molecules29030707] [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: 12/31/2023] [Revised: 01/26/2024] [Accepted: 01/30/2024] [Indexed: 02/12/2024] Open
Abstract
By taking advantage of a sequence of oxidative addition/reductive elimination reactions, Pt(II) cyclometalated derivatives are able to promote a rare C(sp2)-C(sp3) bond coupling, resulting in the production of novel methyl-substituted pyridines and bipyridines. Starting from 6-phenyl-2,2'-bipyridine, the step-by-step full sequence of reactions has been followed, leading to the unprecedented 3-methyl-6-phenyl-2,2'-bipyridine, which was isolated and fully characterized. The synthesis involves the following steps: (1) rollover cyclometalation to give the starting complex [Pt(N^C)(DMSO)Me]; (2) the synthesis of a more electron-rich complex [Pt(N^C)(PPh3)Me] by the substitution of DMSO with triphenylphosphine; (3) oxidative addition with methyl iodide to give the Pt(IV) complex [Pt(N^C)(PPh3)(Me)2(I)]; (4) iodide abstraction with silver tetrafluoborate to give an unstable pentacoordinate intermediate, which rapidly evolves through a carbon-carbon reductive coupling, forming a new C(sp3)-C(sp2) bond; (5) finally, the extrusion and characterization of the newly formed 3-methyl-6-phenyl-2,2'-bipyridine. The reaction has been therefore extended to a well-known classical cyclometalating ligand, 2-phenylpyridine, demonstrating that the method is not restricted to rollover derivatives. Following the same step-by-step procedure, 2-phenylpyridine was converted to 2-o-tolyl-pyridine, displaying the potential application of the method to the larger family of classical cyclometalated complexes. The application of this protocol may be useful to convert an array of heterocyclic compounds to their methyl- or alkyl-substituted analogs.
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Affiliation(s)
- Lorenzo Manca
- Dipartimento di Scienze Chimiche, Fisiche, Matematiche e Naturali, Università degli Studi di Sassari, Via Vienna 2, 07100 Sassari, Italy; (L.M.); (G.S.); (S.S.)
| | - Giacomo Senzacqua
- Dipartimento di Scienze Chimiche, Fisiche, Matematiche e Naturali, Università degli Studi di Sassari, Via Vienna 2, 07100 Sassari, Italy; (L.M.); (G.S.); (S.S.)
- Consorzio Interuniversitario Reattività Chimica e Catalisi (CIRCC), Villa La Rocca, Via Celso Ulpiani, 27, 70126 Bari, Italy
| | - Sergio Stoccoro
- Dipartimento di Scienze Chimiche, Fisiche, Matematiche e Naturali, Università degli Studi di Sassari, Via Vienna 2, 07100 Sassari, Italy; (L.M.); (G.S.); (S.S.)
- Consorzio Interuniversitario Reattività Chimica e Catalisi (CIRCC), Villa La Rocca, Via Celso Ulpiani, 27, 70126 Bari, Italy
| | - Antonio Zucca
- Dipartimento di Scienze Chimiche, Fisiche, Matematiche e Naturali, Università degli Studi di Sassari, Via Vienna 2, 07100 Sassari, Italy; (L.M.); (G.S.); (S.S.)
- Consorzio Interuniversitario Reattività Chimica e Catalisi (CIRCC), Villa La Rocca, Via Celso Ulpiani, 27, 70126 Bari, Italy
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2
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Babu US, Kotipalli R, Nanubolu JB, Reddy MS. Pd-Catalyzed Vicinal Intermolecular Annulations of Iodoarenes, Indoles, and Carbazoles with Enynes. Chemistry 2024; 30:e202302788. [PMID: 37929623 DOI: 10.1002/chem.202302788] [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: 08/31/2023] [Revised: 11/03/2023] [Accepted: 11/06/2023] [Indexed: 11/07/2023]
Abstract
Reaching the formidable C-H corners has been one of the top priorities of organic chemists in the recent past. This prompted us to disclose herein a vicinal annulation of 2-iodo benzoates, indoles, and carbazoles with N-embedded 1,6-enynes through 7-/8-membered palladacycles. The relay does not require the assistance of any directing group, leading to multicyclic scaffolds, which are readily diversified to an array of adducts (with new functional tethers and/or three contiguous stereocenters), in which we showcase a rare benzylic mono-oxygenation.
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Affiliation(s)
- Undamatla Suri Babu
- Department of Oraganic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India
- Academy of Scientific and Innovative Research, Ghaziabad, 201002, India
| | - Ramesh Kotipalli
- Department of Oraganic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India
- Academy of Scientific and Innovative Research, Ghaziabad, 201002, India
| | - Jagadeesh Babu Nanubolu
- Department of Oraganic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India
- Jagadeesh Babu Nanubolu, Analytical Department, CSIR-IICT, Hyderabad, 500007, India
| | - Maddi Sridhar Reddy
- Department of Oraganic Synthesis & Process Chemistry, CSIR-Indian Institute of Chemical Technology, Hyderabad, 500007, India
- Academy of Scientific and Innovative Research, Ghaziabad, 201002, India
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3
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Karak P, Sreelakshmi PA, Chakraborty B, Pal M, Khatua B, Lal Koner A, Choudhury J. Annulation-Induced Hidden Reactivity of the 1,2,4-Triazole Backbone. Angew Chem Int Ed Engl 2023; 62:e202310603. [PMID: 37610555 DOI: 10.1002/anie.202310603] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2023] [Revised: 08/18/2023] [Accepted: 08/23/2023] [Indexed: 08/24/2023]
Abstract
Triazoles are an important class of compounds with widespread applications. Functionalization of the triazole backbone is thus of significant interest. In comparison to 1,2,3-triazoles, C-H activation-functionalization of the congeners 1,2,4-triazoles is surprisingly underdeveloped. Indeed, no such C-H activation-functionalization has been reported for 4-substituted 1,2,4-triazole cores. Furthermore, although denitrogenative ring-opening of 1,2,3-triazoles is well-explored, 1,2,4-triazole/triazolium substrates have not been known to exhibit N-N bond-cleaving ring-opening reactivity so far. In this work, we unveiled an unusual hidden reactivity of the 1,2,4-triazole backbone involving the elusive N-N bond-cleaving ring-opening reaction. This new reactivity was induced by a Satoh-Miura-type C-H activation-annulation at the 1,2,4-triazole motif appended with a pyridine directing group. This unique reaction allowed ready access to a novel class of unsymmetrically substituted 2,2'-dipyridylamines, with one pyridine ring fully-substituted with alkyl groups. The unsymmetrical 2,2'-dipyridylamines were utilized to access unsymmetrical boron-aza-dipyridylmethene fluorescent dyes. Empowered with desirable optical/physical properties such as large Stokes shifts and suitable hydrophobicity arising from optimal alkyl chain length at the fully-substituted pyridine-ring, these dyes were used for intracellular lipid droplet-selective imaging studies, which provided useful information toward designing suitable lipid droplet-selective imaging probes for biomedical applications.
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Affiliation(s)
- Pirudhan Karak
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, 462 066, India
| | - P A Sreelakshmi
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, 462 066, India
| | - Barsha Chakraborty
- Bionanotechnology Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, 462 066, India
| | - Manisha Pal
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, 462 066, India
| | - Bitasik Khatua
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, 462 066, India
| | - Apurba Lal Koner
- Bionanotechnology Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, 462 066, India
| | - Joyanta Choudhury
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research Bhopal, Bhopal, 462 066, India
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4
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Momeni BZ, Abd-El-Aziz AS. Recent advances in the design and applications of platinum-based supramolecular architectures and macromolecules. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2023.215113] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
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5
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Suárez-Lustres A, Martínez-Yáñez N, Velasco-Rubio Á, Varela JA, Saá C. Palladium-Catalyzed [5 + 2] Rollover Annulation of 1-Benzylpyrazoles with Alkynes: A Direct Entry to Tricyclic 2-Benzazepines. Org Lett 2023; 25:794-799. [PMID: 36720009 PMCID: PMC9926515 DOI: 10.1021/acs.orglett.2c04300] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The first Pd-catalyzed [5 + 2] rollover annulation of 1-benzylpyrazoles with alkynes to assemble 10H-benzo[e]pyrazolo[1,5-a]azepines (tricyclic 2-benzazepines) has been developed. The rollover annulation implies a twofold C-H activation of aryl and heteroaryl Csp2-H bonds (C-H/C-H) of 1-benzylpyrazoles (five-atom partners) and alkynes to give the [5 + 2] annulated compounds.
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Maidich L, Pilo MI, Rourke JP, Clarkson GJ, Canu P, Stoccoro S, Zucca A. Classical vs. Non-Classical Cyclometalated Pt(II) Complexes. Molecules 2022; 27:7249. [PMID: 36364075 PMCID: PMC9654721 DOI: 10.3390/molecules27217249] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 10/18/2022] [Accepted: 10/19/2022] [Indexed: 09/10/2023] Open
Abstract
Rollover cyclometalated complexes constitute a family of derivatives which differ from classical cyclometalated species in certain aspects. Various potential application fields have been developed for both classes of compounds, which have both similarities and differences. In order to uncover the relationships and distinctions between these two families of compounds, four Pt(II) cyclometalated complexes derived from 2-phenylpyridine (ppy) and 2,2'-bipyridine (bpy), assumed as prototypical ligands, were compared. For this study, an electron rich isostructural and isoelectronic pair of compounds, [Pt(N^C)Me(PPh3)], and an electron-poorer compound, [Pt(N^C)Cl(PPh3)] were chosen (N^C = ppy or bpy). DFT calculations, cyclic voltammetry, and UV-Vis spectra also helped to shed light into these species. Due to the presence of the more electronegative nitrogen in place of a C-H group, the rollover bpy-H ligand becomes a slightly weaker donor than the classical ppy-H ligand, and hence, generates (slightly) more stable cyclometalated complexes, lower energy frontier molecular orbitals, and electron-poorer platinum centers. On the whole, it was revealed that classical and rollover complexes have overall structural similarity, which contrasts to their somewhat different chemical behavior.
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Affiliation(s)
- Luca Maidich
- Department of Chemical, Physical, Mathematical and Natural Sciences, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Maria I. Pilo
- Department of Chemical, Physical, Mathematical and Natural Sciences, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Jonathan P. Rourke
- School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, UK
| | - Guy J. Clarkson
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Patrizia Canu
- Department of Chemical, Physical, Mathematical and Natural Sciences, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Sergio Stoccoro
- Department of Chemical, Physical, Mathematical and Natural Sciences, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
| | - Antonio Zucca
- Department of Chemical, Physical, Mathematical and Natural Sciences, University of Sassari, Via Vienna 2, 07100 Sassari, Italy
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7
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Shu H, Guo M, Wang M, Zhou M, Zhou B, Xu L, Rao Y, Yin B, Osuka A, Song J. Efficient Synthesis of Multiply Seven‐Membered‐Ring Fused Porphyrins by Rhodium‐Catalyzed [5+2] Annulation. Angew Chem Int Ed Engl 2022; 61:e202209594. [DOI: 10.1002/anie.202209594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Indexed: 11/07/2022]
Affiliation(s)
- Hui Shu
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of China Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081 China
| | - Mengjie Guo
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of China Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081 China
| | - Machongyang Wang
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of China Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081 China
| | - Mingbo Zhou
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of China Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081 China
| | - Bixiang Zhou
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of China Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081 China
| | - Ling Xu
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of China Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081 China
| | - Yutao Rao
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of China Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081 China
| | - Bangshao Yin
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of China Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081 China
| | - Atsuhiro Osuka
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of China Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081 China
| | - Jianxin Song
- Key Laboratory of Chemical Biology and Traditional Chinese Medicine Ministry of Educational of China Key Laboratory of the Assembly and Application of Organic Functional Molecules of Hunan Province College of Chemistry and Chemical Engineering Hunan Normal University Changsha 410081 China
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8
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Shu H, Guo M, Wang M, Zhou M, Zhou B, Xu L, Rao Y, Yin B, Osuka A, Song J. Efficient Synthesis of Multiply Seven‐Membered‐Ring Fused Porphyrins by Rhodium‐Catalyzed [5+2] Annulation. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202209594] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Hui Shu
- Hunan Normal University - Erliban Campus: Hunan Normal University Chemistry CHINA
| | - Mengjie Guo
- Hunan Normal University - Erliban Campus: Hunan Normal University Chemistry CHINA
| | - Machongyang Wang
- Hunan Normal University - Erliban Campus: Hunan Normal University Chemistry CHINA
| | - Mingbo Zhou
- Hunan Normal University - Erliban Campus: Hunan Normal University Chemistry CHINA
| | - Bixiang Zhou
- Hunan Normal University - Erliban Campus: Hunan Normal University Chemistry CHINA
| | - Ling Xu
- Hunan Normal University - Erliban Campus: Hunan Normal University Chemistry CHINA
| | - Yutao Rao
- Hunan Normal University - Erliban Campus: Hunan Normal University Chemistry CHINA
| | - Bangshao Yin
- Hunan Normal University - Erliban Campus: Hunan Normal University Chemistry CHINA
| | - Atsuhiro Osuka
- Hunan Normal University - Erliban Campus: Hunan Normal University Chemistry CHINA
| | - Jianxin Song
- Hunan Normal University Chemistry Yue Lu Qu Lushan Road 36 410081 Changsha CHINA
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9
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Perutz RN, Sabo‐Etienne S, Weller AS. Metathesis by Partner Interchange in σ‐Bond Ligands: Expanding Applications of the σ‐CAM Mechanism. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202111462] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | - Sylviane Sabo‐Etienne
- CNRS LCC (Laboratoire de Chimie de Coordination) 205 route de Narbonne, BP 44099 F-31077 Toulouse Cedex 4 France
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10
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Karak P, Rana SS, Choudhury J. Cationic π-extended heteroaromatics via a catalytic C-H activation annulative alkyne-insertion sequence. Chem Commun (Camb) 2021; 58:133-154. [PMID: 34849515 DOI: 10.1039/d1cc05590a] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Cationic π-conjugated organic molecules have broad applications in materials science as next-generation organic materials. The annulative alkyne-insertion π-extension (AAIPEX) strategy has emerged as a promising synthetic approach for the rapid synthesis of cationic polycyclic heteroaromatic compounds (cPHACs) in a single step. The AAIPEX reaction provides a synthetic shortcut to achieve complex organic molecules from simple (hetero)arene templates and alkynes as π-extending partners, which would otherwise be difficult to achieve using traditional methods. In general, a step-economic AAIPEX protocol proceeds via C-H activation of unfunctionalized heteroarene templates, followed by alkyne insertion-annulation to furnish cPHACs. In this Feature Article, recent progress in the AAIPEX strategy to construct cPHACs is described along with brief illustrations of the resulting cPHACs in luminescence-related applications.
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Affiliation(s)
- Pirudhan Karak
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal 462 066, India.
| | - Samim Sohel Rana
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal 462 066, India.
| | - Joyanta Choudhury
- Organometallics & Smart Materials Laboratory, Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal 462 066, India.
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11
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Nabavizadeh SM, Molaee H, Haddadi E, Niroomand Hosseini F, Hoseini SJ, Abu-Omar MM. Tetranuclear rollover cyclometalated organoplatinum-rhenium compounds; C-I oxidative addition and C-C reductive elimination using a rollover cycloplatinated dimer. Dalton Trans 2021; 50:15015-15026. [PMID: 34609403 DOI: 10.1039/d1dt02086b] [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
The novel tetranuclear Pt(IV)-Re(VII) complex [Pt2Me4(OReO3)2(PMePh2)2(µ-bpy-2H)], 4, is synthesized through the reaction of silver perrhenate with a new rollover cycloplatinated(IV) complex [Pt2Me4I2(PMePh2)2(µ-bpy-2H)], 3. In complex 4, while 2,2'-bipyridine (bpy) acts as a linker between two Pt metal centers, oxygen acts as a mono-bridging atom between Pt and Re centers through an unsupported Pt(IV)-O-Re(VII) bridge. The precursor rollover cycloplatinated(IV) complex 3 is prepared by the MeI oxidative addition reaction of the rollover cycloplatinated(II) complex [Pt2Me2(PMePh2)2(µ-bpy-2H)], 2. Complex 2 shows a metal-to-ligand charge-transfer band in the visible region, which was used to investigate the kinetics and mechanism of its double MeI oxidative addition reaction. Based on the experimental findings, the classical SN2 mechanism was suggested for both steps and supported by computational studies. All complexes are fully characterized using multinuclear NMR spectroscopy and elemental analysis. Attempts to grow crystals of the rollover cycloplatinated(IV) dimer 3 yielded a new dimer rollover cyclometalated complex [Pt2I2(PMePh2)2(µ-bpy-2H)], 5, presumably from the C-C reductive elimination of ethane. The identity of complex 5 was confirmed by single crystal X-ray diffraction analysis.
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Affiliation(s)
- S Masoud Nabavizadeh
- Professor Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71467-13565, Iran.
| | - Hajar Molaee
- Professor Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71467-13565, Iran.
| | - Elahe Haddadi
- Professor Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71467-13565, Iran.
| | | | - S Jafar Hoseini
- Professor Rashidi Laboratory of Organometallic Chemistry, Department of Chemistry, College of Sciences, Shiraz University, Shiraz 71467-13565, Iran.
| | - Mahdi M Abu-Omar
- Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA.
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12
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Perutz RN, Sabo-Etienne S, Weller AS. Metathesis by Partner Interchange in σ-Bond Ligands: Expanding Applications of the σ-CAM Mechanism. Angew Chem Int Ed Engl 2021; 61:e202111462. [PMID: 34694734 PMCID: PMC9299125 DOI: 10.1002/anie.202111462] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Indexed: 12/13/2022]
Abstract
In 2007 two of us defined the σ‐Complex Assisted Metathesis mechanism (Perutz and Sabo‐Etienne, Angew. Chem. Int. Ed. 2007, 46, 2578–2592), that is, the σ‐CAM concept. This new approach to reaction mechanisms brought together metathesis reactions involving the formation of a variety of metal–element bonds through partner‐interchange of σ‐bond complexes. The key concept that defines a σ‐CAM process is a single transition state for metathesis that is connected by two intermediates that are σ‐bond complexes while the oxidation state of the metal remains constant in precursor, intermediates and product. This mechanism is appropriate in situations where σ‐bond complexes have been isolated or computed as well‐defined minima. Unlike several other mechanisms, it does not define the nature of the transition state. In this review, we highlight advances in the characterization and dynamic rearrangements of σ‐bond complexes, most notably alkane and zincane complexes, but also different geometries of silane and borane complexes. We set out a selection of catalytic and stoichiometric examples of the σ‐CAM mechanism that are supported by strong experimental and/or computational evidence. We then draw on these examples to demonstrate that the scope of the σ‐CAM mechanism has expanded to classes of reaction not envisaged in 2007 (additional σ‐bond ligands, agostic complexes, sp2‐carbon, surfaces). Finally, we provide a critical comparison to alternative mechanisms for metathesis of metal–element bonds.
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Affiliation(s)
- Robin N Perutz
- Department of Chemistry, University of York, York, YO10 5DD, UK
| | - Sylviane Sabo-Etienne
- CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, BP 44099, F-31077, Toulouse Cedex 4, France
| | - Andrew S Weller
- Department of Chemistry, University of York, York, YO10 5DD, UK
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13
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Medici S, Peana M, Pelucelli A, Zoroddu MA. Rh(I) Complexes in Catalysis: A Five-Year Trend. Molecules 2021; 26:2553. [PMID: 33925725 PMCID: PMC8125654 DOI: 10.3390/molecules26092553] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Revised: 04/23/2021] [Accepted: 04/24/2021] [Indexed: 11/16/2022] Open
Abstract
Rhodium is one of the most used metals in catalysis both in laboratory reactions and industrial processes. Despite the extensive exploration on "classical" ligands carried out during the past decades in the field of rhodium-catalyzed reactions, such as phosphines, and other common types of ligands including N-heterocyclic carbenes, ferrocenes, cyclopentadienyl anion and pentamethylcyclopentadienyl derivatives, etc., there is still lively research activity on this topic, with considerable efforts being made toward the synthesis of new preformed rhodium catalysts that can be both efficient and selective. Although the "golden age" of homogeneous catalysis might seem over, there is still plenty of room for improvement, especially from the point of view of a more sustainable chemistry. In this review, temporally restricted to the analysis of literature during the past five years (2015-2020), the latest findings and trends in the synthesis and applications of Rh(I) complexes to catalysis will be presented. From the analysis of the most recent literature, it seems clear that rhodium-catalyzed processes still represent a stimulating challenge for the metalloorganic chemist that is far from being over.
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Affiliation(s)
- Serenella Medici
- Department of Chemistry and Pharmacy, University of Sassari, Vienna 2, 07100 Sassari, Italy; (A.P.); (M.A.Z.)
| | - Massimiliano Peana
- Department of Chemistry and Pharmacy, University of Sassari, Vienna 2, 07100 Sassari, Italy; (A.P.); (M.A.Z.)
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14
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Pischedda S, Stoccoro S, Zucca A, Sciortino G, Ortu F, Clarkson GJ. Synthesis and characterization of new Pd(ii) and Pt(ii) complexes with 3-substituted 1-(2-pyridyl)imidazo[1,5-a]pyridine ligands. Dalton Trans 2021; 50:4859-4873. [PMID: 33877183 DOI: 10.1039/d1dt00546d] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Several palladium(ii) and platinum(ii) complexes (1-20) of general formula [M(Ln)(X)(Y)] [M = Pd, X = Y = Cl (1-Cl-4-Cl), X = Y = OAc (1-OAc-4-OAc); M = Pt: X = Y = Cl (5-8); M = Pd, X = Cl, Y = CH3 (9-12); M = Pt, X = Cl, Y = CH3 (13-16) or X = Y = CH3 (17-20); n = 1-4] have been synthesized by reaction of different Pd(ii) and Pt(ii) derivatives with various 3-substituted 1-(2-pyridyl)-imidazo[1,5-a]pyridines; i.e.Ln = 1-(2-pyridyl)-3-arylimidazo[1,5-a]pyridine (aryl = Phenyl, L1; 2-o-Tolyl, L2; Mesityl, L3) and 1-(2-pyridyl)-3-benzylimidazo[1,5-a]pyridine (L4). Detailed spectroscopic investigation (including IR, mono- and bi-dimensional 1H NMR) and elemental analysis has been performed for all these species, allowing their complete characterization. Ln act as N,N-bidentate ligands and coordinate the metal centers in a chelate fashion through the pyridyl (Npy) and the pyridine-like nitrogen atom of the imidazo[1,5-a]pyridine group (Nim). The X-ray structural analysis performed on two of Pd(ii) and three Pt(ii) complexes, namely [Pd(L2)(CH3)Cl] (10), [Pd(L3)(CH3)Cl] (11) and [Pt(L1)Cl2] (5), [Pt(L4)Cl2] (8), [Pt(L2)(CH3)Cl] (14) confirmed the spectroscopic and analytical data. Finally DFT studies unveiled the structural reasons behind the inertia of the synthesised compounds toward metalation, identified as the higher angle steric strain in comparison with the analogous bipyridine complexes.
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Affiliation(s)
- Sara Pischedda
- Dipartimento di Chimica e Farmacia, Università degli Studi di Sassari, via Vienna 2, 07100 Sassari, Italy.
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