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Predarska I, Körber W, Lönnecke P, Gelman D, Hey-Hawkins E. Synthesis and catalytic activity of heterobimetallic Au/M (M = Rh III, Ir III) complexes with ditopic mono- and triphosphane ligands. Dalton Trans 2024. [PMID: 38953230 DOI: 10.1039/d4dt01247j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/03/2024]
Abstract
A series of heterobimetallic complexes Au/M (M = RhIII, IrIII) were prepared on the basis of two ditopic ligands: a monophosphane ligand L1H and a triphosphane ligand L2H. The complexes were fully characterised, including single-crystal X-ray diffraction studies. Catalytic activity of cationic L1/AuI/IrIII and L2/AuI/IrIII bis(trifluoromethane)sulfonimide was analysed through their capacity to induce allenyl ether rearrangement and cycloisomerisation of N-propargyl benzamide. While cationic L1/AuI/IrIII showed some ability to induce allenyl ether rearrangement, no conversion was observed for cationic L2/AuI/IrIII. Similarly, N-propargyl benzamide could undergo cycloisomerisation in the presence of cationic L1/AuI/IrIII, whereas cationic L2/AuI/IrIII was again inactive. These findings highlight how crucial the surroundings of the metal centre are to the catalytic activity. Catalytic activity is only possible when Au has a free coordination site; the gold complex becomes inactive when the tridentate ligand is present.
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Affiliation(s)
- Ivana Predarska
- Leipzig University, Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103 Leipzig, Germany.
| | - Wieland Körber
- Leipzig University, Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103 Leipzig, Germany.
| | - Peter Lönnecke
- Leipzig University, Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103 Leipzig, Germany.
| | - Dmitri Gelman
- The Hebrew University, Institute of Chemistry, Edmond Safra Campus, 9190401 Jerusalem, Israel.
| | - Evamarie Hey-Hawkins
- Leipzig University, Faculty of Chemistry and Mineralogy, Institute of Inorganic Chemistry, Johannisallee 29, 04103 Leipzig, Germany.
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Campagnolo F, Aneggi E, Baratta W, Munir T, Zuccaccia D. Diffusion Nuclear Magnetic Resonance Measurements on Cationic Gold (I) Complexes in Catalytic Conditions: Counterion and Solvent Effects. Molecules 2024; 29:3018. [PMID: 38998970 PMCID: PMC11243661 DOI: 10.3390/molecules29133018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 06/18/2024] [Accepted: 06/20/2024] [Indexed: 07/14/2024] Open
Abstract
The amount of free ions, ion pairs, and higher aggregate of the possible species present in a solution during the gold(I)-catalyzed alkoxylation of unsaturated hydrocarbon, i.e., ISIP (inner sphere ion pair) [(NHC)AuX] and OSIP (outer sphere ion pairs) [(NHC)Au(TME)X] [NHC 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene; TME = tetramethylethylene (2,3-bis methyl-butene); X- = Cl-, BF4-, OTf-; and OTs- BArF4- (ArF = 3,5-(CF3)2C6H3)], has been determined. The 1H and 19F DOSY NMR measurements conducted in catalytic conditions indicate that the dissociation degree (α) of the equilibrium ion pair/free ions {[(NHC)Au(TME)X] [(NHC)Au(TME)]+ + X-} depends on the nature of the counterion (X-) when chloroform is the catalytic solvent: while the compounds containing OTs- and OTf- as the counterion gave a low α (which means a high number of ion pairs) of 0.13 and 0.24, respectively, the compounds containing BF4- and BArF4- showed higher α values of 0.36 and 0.32, respectively. These results experimentally confirm previous deductions based on catalytic and theoretical data: the lower the α value, the greater the catalytic activity because the anion that can activate methanol during a nucleophilic attack, although the lower propensity to activate methanol of BF4- and BArF4-, as suggested by the DFT calculations, cannot be completely overlooked. As for the effect of the solvent, α increases as the dielectric constant increases, as expected, and in particular, green solvents with high dielectric constants show a very high α (0.90, 0.84, 0.80, and 0.70 for propylene carbonate, γ-valerolactone, acetone, and methanol, respectively), thus confirming that the moderately high activity of NHC-Au-OTf in these solvents is due to the specific effect of polar functionalities (O-H, C=O, O-R) in activating methanol. Finally, the DOSY measurements conducted in p-Cymene show the formation of quadrupole species: under these conditions, the anion can better exercise its 'template' and 'activating' roles, giving the highest TOF.
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Affiliation(s)
- Filippo Campagnolo
- Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy
| | - Eleonora Aneggi
- Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy
| | - Walter Baratta
- Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy
| | - Talha Munir
- Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy
| | - Daniele Zuccaccia
- Dipartimento di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy
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Segato J, Aneggi E, Baratta W, Campagnolo F, Belpassi L, Belanzoni P, Zuccaccia D. Experimental and Theoretical Investigation of Ion Pairing in Gold(III) Catalysts. Organometallics 2023; 42:2973-2982. [PMID: 37886625 PMCID: PMC10599130 DOI: 10.1021/acs.organomet.3c00293] [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: 06/29/2023] [Indexed: 10/28/2023]
Abstract
The ion pairing structure of the possible species present in solution during the gold(III)-catalyzed hydration of alkynes: [(ppy)Au(NHC)Y]X2 and [(ppy)Au(NHC)X]X [ppy = 2-phenylpyridine, NHC = NHCiPr = 1,3-bis(2,6-di-isopropylphenyl)-imidazol-2-ylidene; NHC = NHCmes = 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene X = Cl-, BF4-, OTf-; Y = H2O and 3-hexyne] are determined. The nuclear overhauser effect nuclear magnetic resonance (NMR) experimental measurements integrated with a theoretical description of the system (full optimization of different ion pairs and calculation of the Coulomb potential surface) indicate that the preferential position of the counterion is tunable through the choice of the ancillary ligands (NHCiPr, NHCmes, ppy, and Y) in [(ppy)Au(NHC)(3-hexyne)]X2 activated complexes that undergo nucleophilic attack. The counterion can approach near NHC, pyridine ring of ppy, and gold atom. From these positions, the anion can act as a template, holding water in the right position for the outer-sphere attack, as observed in gold(I) catalysts.
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Affiliation(s)
- Jacopo Segato
- Dipartimento
di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy
| | - Eleonora Aneggi
- Dipartimento
di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy
| | - Walter Baratta
- Dipartimento
di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy
| | - Filippo Campagnolo
- Dipartimento
di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy
| | - Leonardo Belpassi
- Istituto
di Scienze e Tecnologie Chimiche (SCITEC), Consiglio Nazionale delle
Ricerche c/o Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
| | - Paola Belanzoni
- Istituto
di Scienze e Tecnologie Chimiche (SCITEC), Consiglio Nazionale delle
Ricerche c/o Dipartimento di Chimica, Biologia e Biotecnologie, Università degli Studi di Perugia, Via Elce di Sotto 8, 06123 Perugia, Italy
- Dipartimento
di Chimica, Biologia e Biotecnologie, Università
degli Studi di Perugia, 06123 Perugia, Italy
| | - Daniele Zuccaccia
- Dipartimento
di Scienze Agroalimentari, Ambientali e Animali, Sezione di Chimica, Università di Udine, Via Cotonificio 108, I-33100 Udine, Italy
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Tzouras NV, Gobbo A, Pozsoni NB, Chalkidis SG, Bhandary S, Van Hecke K, Vougioukalakis GC, Nolan SP. Hydrogen bonding-enabled gold catalysis: ligand effects in gold-catalyzed cycloisomerizations in hexafluoroisopropanol (HFIP). Chem Commun (Camb) 2022; 58:8516-8519. [PMID: 35801509 DOI: 10.1039/d2cc03056j] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Gold catalysis has witnessed immense evolution in recent years, yet it still requires the use of activators to render the common [AuCl(L)] complexes catalytically active. Herein, the H-bonding donor properties of hexafluoroisopropanol (HFIP) are utilized for Au-Cl bond activation and the ancillary ligand and counteranion effects on cycloisomerization reactions are showcased in HFIP as solvent.
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Affiliation(s)
- Nikolaos V Tzouras
- Department of Chemistry and Centre of Sustainable Chemistry, Ghent University, Krijgslaan 281, S-3, 9000, Ghent, Belgium. .,Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece.
| | - Alberto Gobbo
- Department of Chemistry and Centre of Sustainable Chemistry, Ghent University, Krijgslaan 281, S-3, 9000, Ghent, Belgium.
| | - Nestor Bracho Pozsoni
- Department of Chemistry and Centre of Sustainable Chemistry, Ghent University, Krijgslaan 281, S-3, 9000, Ghent, Belgium.
| | - Savvas G Chalkidis
- Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece.
| | - Subhrajyoti Bhandary
- Department of Chemistry and Centre of Sustainable Chemistry, Ghent University, Krijgslaan 281, S-3, 9000, Ghent, Belgium.
| | - Kristof Van Hecke
- Department of Chemistry and Centre of Sustainable Chemistry, Ghent University, Krijgslaan 281, S-3, 9000, Ghent, Belgium.
| | - Georgios C Vougioukalakis
- Department of Chemistry, National and Kapodistrian University of Athens, Panepistimiopolis, 15771, Athens, Greece.
| | - Steven P Nolan
- Department of Chemistry and Centre of Sustainable Chemistry, Ghent University, Krijgslaan 281, S-3, 9000, Ghent, Belgium.
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