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Newman PD, Platts JA, Alrashidi B, Pope SJA, Kariuki BM. A noble nexus: a phosphino-phen ligand for tethering precious metals. Dalton Trans 2024; 53:15539-15550. [PMID: 39229681 DOI: 10.1039/d4dt02130d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/05/2024]
Abstract
Controlled formation of mixed-metal bimetallics was achieved via two derivatised 1,10-phenanthroline ligands bearing an imino- or amino-phosphine appendage at the 5-position. Selective coordination of the phen group to the [Re(CO)3Cl] core was achieved enabling precise construction of bimetallic complexes with a second rhenium centre or with gold. The mixed Ru/Au complex was similarly obtained with the imino-phosphine but access to the heterobimetallic iridium systems required prior formation of the P-bound gold complexes subsequent to the introduction of the [Ir(Ppy)2]+ fragment. The Re/Pd, Re/Pt, Ir/Pd and Ir/Pt compounds were prepared from the combination of κ-N'',P-Pd(Pt)Cl2 and the appropriate rhenium or iridium precursors. Spectroscopic and theoretical analyses have been employed to investigate the structural and electronic impact of the second metal.
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Affiliation(s)
- Paul D Newman
- School of Chemistry, Cardiff University, Cardiff, Wales, UK, CF10 3AT.
| | - James A Platts
- School of Chemistry, Cardiff University, Cardiff, Wales, UK, CF10 3AT.
| | - Basheer Alrashidi
- School of Chemistry, Cardiff University, Cardiff, Wales, UK, CF10 3AT.
| | - Simon J A Pope
- School of Chemistry, Cardiff University, Cardiff, Wales, UK, CF10 3AT.
| | - Benson M Kariuki
- School of Chemistry, Cardiff University, Cardiff, Wales, UK, CF10 3AT.
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2
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Liu WC, Gabbaï FP. Characterization of a Lewis adduct in its inner and outer forms. Science 2024; 385:1184-1188. [PMID: 39265017 DOI: 10.1126/science.adp7465] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Accepted: 07/16/2024] [Indexed: 09/14/2024]
Abstract
The entrance channel of bimolecular reactions sometimes involves the formation of outer complexes as weakly bound, fleeting intermediates. Here, we characterize such an outer complex in a system that models the bimolecular, C-O bond-forming reaction of a phosphine oxide Lewis base with a carbenium Lewis acid. Crystallographic studies show that the C-O distance in the outer form exceeds that of the final or inner adduct by 1.1 angstroms. As the system samples the two forms of the complex, which correspond to minima on the corresponding potential energy surface, the C-O linkage switches from a secondary interaction in the outer complex to a dative bond in the inner complex. This phenomenon is harnessed as a functional feature to stabilize xanthylium-based photoredox catalysts.
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Affiliation(s)
- Wei-Chun Liu
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
| | - François P Gabbaï
- Department of Chemistry, Texas A&M University, College Station, TX 77843-3255, USA
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3
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Litle ED, Gabbaï FP. Double axial stabilization of a carbenium ion via convergent PO → C + tetrel bonding. Chem Commun (Camb) 2024; 60:690-693. [PMID: 38108149 DOI: 10.1039/d3cc04729f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Our efforts in carbocation chemistry have led us to target examples of such species stabilized intramolecularly by tetrel bonding. Described here is an example of such a compound in which a triaryl carbenium is stabilized intramolecularly by two convergent PO → Ccarbenium interactions, as confirmed by structural studies. The formation of this new motif favorably impacts the reversibility of the first and second reduction of the carbenium center. It also has profound influence on the Lewis acidity of the carbenium center which is lower than that of the unsubstituted parent carbenium by seven orders of magnitude.
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Affiliation(s)
- Elishua D Litle
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.
| | - François P Gabbaï
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.
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4
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Litle ED, Gabbaï FP. A cationic gold-fluorenyl complex with a dative Au → C + bond: synthesis, structure, and carbophilic reactivity. Chem Commun (Camb) 2023; 59:603-606. [PMID: 36533545 DOI: 10.1039/d2cc05436a] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aiming to study the interaction of gold with the highly Lewis acidic fluorenyl cation, we synthesised (o-[Ph2P(C6H4)Flu)AuCl(tht)][BF4] ([2][BF4]) and (o-Ph2P(C6H4)Flu)AuCl2 (3) (Flu = 9-fluorenyl) and found that the latter could be converted into [(o-Ph2P(C6H4)Flu)AuCl]+ ([4]+) upon treatment with NaBArF24 (BArF24 = B(3,5-C6H3(CF3)2)4). [4]+, which has been isolated as a chloride-bridged dimer, readily catalyses the cycloisomerisation of 2-allyl-2-(2-propynyl)malonate. Computational results show that [4]+ possesses a strong Au → C+ bond and readily activates enynes.
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Affiliation(s)
- Elishua D Litle
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.
| | - François P Gabbaï
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.
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5
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Liu WC, Gabbaï FP. Placing gold on a π +-surface: ligand design and impact on reactivity. Chem Sci 2023; 14:277-283. [PMID: 36687358 PMCID: PMC9811580 DOI: 10.1039/d2sc05574k] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2022] [Accepted: 11/21/2022] [Indexed: 11/24/2022] Open
Abstract
We describe a novel gold chloride complex supported by an ambiphilic phosphine/xanthylium ligand in which the AuCl moiety interacts with the π+ surface of the xanthylium unit as indicated by structural studies. Energy decomposition analyses carried out on a model system indicates the prevalence of non-covalent interactions in which the electrostatic and dispersion terms cumulatively dominate. The presence of these AuCl-π+ interactions correlates with the high catalytic activity of this complex in the cyclisation of 2-(phenylethynyl)phenylboronic acid, N-propargyl-t-butylamide, and 2-allyl-2-(2-propynyl)malonate. Comparison with the significantly less active acridinium and the 9-oxa-10-boraanthracene analogues reinforces this conclusion.
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Affiliation(s)
- Wei-Chun Liu
- Department of Chemistry, Texas A&M UniversityCollege StationTX 77843USA
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6
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Zheng C, Tang Y, Yu B. Tri( N-carbazolyl)phosphine Gold(I) Complexes: Structural and Catalytic Activity Studies. Inorg Chem 2022; 61:16874-16886. [PMID: 36219576 DOI: 10.1021/acs.inorgchem.2c02902] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Twelve tri(N-carbazolyl)phosphine gold(I) complexes, bearing both protonated and deuterated aryl phosphorous triamide-type ligands, have been synthesized and characterized. An elusive Au-H(D) interaction between the H(D) atoms of the tri(N-carbazolyl)phosphine ligand at the H-1(D-1) position of the carbazolyl ring and the central gold atom was observed. Complexes 5(H)/5(D) bearing the dibrominated tri(N-carbazolyl)phosphine ligand exhibit isotopic polymorphism, in which two dramatically different crystal-packing modes between the protonated and deuterated forms occur. The catalytic potential of these complexes has been showcased in the gold(I)-catalyzed glycosylation with glycosyl o-alkynylbenzoates as donors, with TON being up to 27 000.
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Affiliation(s)
- Chang Zheng
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China
| | - Yu Tang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
| | - Biao Yu
- School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou 310024, China.,State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai 200032, China
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7
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Park G, Karimi M, Liu W, Gabbaï FP. Green‐Light‐Driven Reductive Elimination of Chlorine from a Carbene‐Xanthylium Gold(III) Complex. Angew Chem Int Ed Engl 2022; 61:e202206265. [DOI: 10.1002/anie.202206265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2022] [Indexed: 11/07/2022]
Affiliation(s)
- Gyeongjin Park
- Department of Chemistry Texas A&M University College Station TX 77843 USA
| | | | - Wei‐Chun Liu
- Department of Chemistry Texas A&M University College Station TX 77843 USA
| | - François P. Gabbaï
- Department of Chemistry Texas A&M University College Station TX 77843 USA
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8
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Gryaznova TV, Nikanshina EO, Fayzullin RR, Islamov DR, Tarasov MV, Kholin KV, Budnikova YH. EPR-electrochemical monitoring of P–C coupling: Towards one-step electrochemical phosphorylation of acridine. Electrochim Acta 2022. [DOI: 10.1016/j.electacta.2022.140946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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9
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Liu WC, Gabbai F. Fluoride ion sensing with an acridinium borane. CAN J CHEM 2022. [DOI: 10.1139/cjc-2022-0080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
With our continuing interest in the chemistry of cationic boranes, we have synthesizedthe tetrafluoroborate salt of 1-dimesitylboron-4-(N-methyl-9-acridinium)-phenylene which acts as a turn-on fluoride anion sensor, visibly changing from yellow to orange upon binding fluoride. To understand this reactivity, we spectroscopically and computationally analyzed the cation and triarylfluoroborate adduct. UV-vis spectroscopy and TD-DFT revealed the basis of the color change to be a red shift in a low-energy absorption band resulting from intramolecular charge-transfer. Electrochemical studies were undertaken to further probe this system. Cyclic voltammetry indicated a reversible one-electron reduction for the cation and a cathodic shift of -0.12 V in the first reduction wave upon fluoride binding. Chemical reduction of the cation yielded the acridine borane radical which was verified by EPR spectroscopy.
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Affiliation(s)
- Wei-Chun Liu
- Texas A&M University, 14736, Department of Chemistry, College Station, United States
| | - Francois Gabbai
- Texas A&M University, 14736, Department of Chemistry, College Station, United States
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10
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Litle ED, Gabbaï FP. Metal→Carbon Dative Bonding. Angew Chem Int Ed Engl 2022; 61:e202201841. [DOI: 10.1002/anie.202201841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Indexed: 11/10/2022]
Affiliation(s)
- Elishua D. Litle
- Department of Chemistry Texas A&M University College Station TX 77843 USA
| | - François P. Gabbaï
- Department of Chemistry Texas A&M University College Station TX 77843 USA
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11
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Park G, Karimi M, Liu WC, Gabbai FP. Green‐Light‐Driven Reductive Elimination of Chlorine from a Carbene‐Xanthylium Gold(III) Complex. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202206265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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12
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Litle ED, Gabbaï FP. Metal→Carbon Dative Bonding. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202201841] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Elishua D. Litle
- Department of Chemistry Texas A&M University College Station TX 77843 USA
| | - François P. Gabbaï
- Department of Chemistry Texas A&M University College Station TX 77843 USA
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13
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Zhou J, Litle ED, Gabbaï FP. Isolation and reactivity of a gold(I) hydroxytrifluoroborate complex stabilized by anion-π + interactions. Chem Commun (Camb) 2021; 57:10154-10157. [PMID: 34486616 DOI: 10.1039/d1cc04105c] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A 9,9-dimethylxanthene-based ligand substituted at the 4- and 5-positions by a phosphine and a xanthylium unit, respectively, has been prepared and converted into an AuCl complex, the structure of which reveals an intramolecular Au-Cl⋯π+ interaction. This new ligand platform was also found to support the formation of an unprecedented hydroxytrifluoroborate derivative featuring a "hard/soft" mismatched Au-μ(OH)-BF3 motif. Despite its surprising stability, this gold hydroxytrifluoroborate complex is a remarkably potent carbophilic catalyst which readily activates alkynes, without activator.
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Affiliation(s)
- Jiliang Zhou
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.
| | - Elishua D Litle
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.
| | - François P Gabbaï
- Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.
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14
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Shaikh AC, Veleta JM, Moutet J, Gianetti TL. Trioxatriangulenium (TOTA +) as a robust carbon-based Lewis acid in frustrated Lewis pair chemistry. Chem Sci 2021; 12:4841-4849. [PMID: 34168760 PMCID: PMC8179643 DOI: 10.1039/d0sc05893a] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Accepted: 02/07/2021] [Indexed: 12/15/2022] Open
Abstract
We report the reactivity between the water stable Lewis acidic trioxatriangulenium ion (TOTA+) and a series of Lewis bases such as phosphines and N-heterocyclic carbene (NHC). The nature of the Lewis acid-base interaction was analyzed via variable temperature (VT) NMR spectroscopy, single-crystal X-ray diffraction, UV-visible spectroscopy, and DFT calculations. While small and strongly nucleophilic phosphines, such as PMe3, led to the formation of a Lewis acid-base adduct, frustrated Lewis pairs (FLPs) were observed for sterically hindered bases such as P( t Bu)3. The TOTA+-P( t Bu)3 FLP was characterized as an encounter complex, and found to promote the heterolytic cleavage of disulfide bonds, formaldehyde fixation, dehydrogenation of 1,4-cyclohexadiene, heterolytic cleavage of the C-Br bonds, and interception of Staudinger reaction intermediates. Moreover, TOTA+ and NHC were found to first undergo single-electron transfer (SET) to form [TOTA]·[NHC]˙+, which was confirmed via electron paramagnetic resonance (EPR) spectroscopy, and subsequently form a [TOTA-NHC]+ adduct or a mixture of products depending the reaction conditions used.
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Affiliation(s)
- Aslam C Shaikh
- University of Arizona, Department of Chemistry and Biochemistry Tucson AZ USA
| | - José M Veleta
- University of Arizona, Department of Chemistry and Biochemistry Tucson AZ USA
| | - Jules Moutet
- University of Arizona, Department of Chemistry and Biochemistry Tucson AZ USA
| | - Thomas L Gianetti
- University of Arizona, Department of Chemistry and Biochemistry Tucson AZ USA
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