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Race JJ, Hudson LA, Albrecht M. Stable CAAC-Triazenes: A New Nitrogen Ligand System With Donor and Conformational Flexibility, and With Application in Olefin Activation Catalysis. Chemistry 2024; 30:e202400400. [PMID: 38687878 DOI: 10.1002/chem.202400400] [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: 01/30/2024] [Revised: 04/30/2024] [Accepted: 04/30/2024] [Indexed: 05/02/2024]
Abstract
N-heterocyclic imines such as pyridylidene amines impart high catalytic activity when coordinated to a transition metal, largely imposed by their electronic flexibility. Here, this donor flexibility has been applied for the first time to CAAC-based systems through the synthesis of CAAC-triazenes. These new ligands offer a larger π-conjugation that extends from the N-heterocyclic carbene through three nitrogens rather than just one, as observed in N-heterocyclic imines. We demonstrate the straightforward synthesis of three new CAAC-triazenes containing different substituents on the terminal triazene nitrogen. These compounds are remarkably stable up to 120 °C without loss of N2 as typically observed with similar triazenes. E-to-Z isomerization within the triazene is instigated by UV light and is partially reversible dependent on the triazene substituent. The quinoline-substituted CAAC-triazene 1-Q has been applied as an L,L'-type ligand in the synthesis of [PdCl2(1-Q)], [PdCl(Me)(1-Q)] and [Pd(Me)(H2O(1-Q)]+. E-to-Z ligand isomerization also occurs when coordinated to PdCl2, providing access to on-metal manipulation. The cationic complex [PdMe(H2O)(1-Q)]+ is a precatalyst for oligomerization of ethylene to form initially 2-butene and subsequently linear and branched C8-C12 products from butene activation. Moreover, isomerization of 1-hexene takes place efficiently with exceptionally low catalyst loading (10 ppm) and up to 74,000 turnover numbers.
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Affiliation(s)
- James J Race
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012, Bern
| | - Luke A Hudson
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012, Bern
| | - Martin Albrecht
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012, Bern
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2
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Bukvic AJ, Kesselring V, Aeschlimann M, Albrecht M. Pincer Platinum(II) Hydrides: High Stability Imparted by Donor-Flexible Pyridylidene Amide Ligands and Evidence for Adduct Formation before Protonation. Inorg Chem 2023; 62:2905-2912. [PMID: 36719961 DOI: 10.1021/acs.inorgchem.2c04363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Donor-flexible ligands are an emerging class of noninnocent ligands. Their ability to adapt their donating strength toward a metal center has had numerous catalytic advantages yet has never been utilized to stabilize and isolate intermediate complexes within these processes. We demonstrate through the use of a pincer ligand containing two donor-flexible pyridylidene amide (PYA) arms in coordination with platinum(II) that this ligand adaptability revealed remarkably stable hydride and formate complexes. These are typically fleeting catalytic intermediates within formic acid dehydrogenation and CO2 hydrogenation catalytic cycles. The PYA platinum hydride complexes are indefinitely stable in air, while formate complexes show no sign of β-hydrogen elimination. This robustness allowed us to investigate hydride protonation as a seemingly simple reaction, though in-depth kinetic analysis reveals a pre-equilibrium step prior to platinum hydride protonation. This initial step has been attributed to adduct formation and is slower than the protonation, and therefore a relevant aspect when designing catalytic cycles for hydrogen release and its microscopic reverse, viz., hydrogen uptake.
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Affiliation(s)
- Alexander J Bukvic
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Vera Kesselring
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Michael Aeschlimann
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Martin Albrecht
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
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3
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Lentz N, Albrecht M. A Low-Coordinate Iridium Complex with a Donor-Flexible O,N-Ligand for Highly Efficient Formic Acid Dehydrogenation. ACS Catal 2022. [DOI: 10.1021/acscatal.2c04113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Nicolas Lentz
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Martin Albrecht
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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4
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Bukvic AJ, Albrecht M. Pincer and Macrocyclic Pyridylidene Amide (PYA) Au III Complexes. Inorg Chem 2022; 61:14038-14045. [PMID: 35994319 DOI: 10.1021/acs.inorgchem.2c02030] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Gold-based homogeneous catalysis is dominated by redox neutral AuI systems. Redox-active gold-based catalysts are less common, principally because of redox cycles between AuI and AuIII being hampered by unfavorable potentials. We report gold(III) complexes containing pincer-based, donor-flexible pyridylidene amide (PYA) ligands to address these issues. These complexes act as electron reservoirs through two limiting resonance structures consisting of either soft, imine coordination sites or harder, zwitterionic amide donors. We further alter the donor properties by using the ortho-, meta-, and para-pyridylidene amide variants of the PYA pincer arms. These bis-PYA pincer ligands exhibited a high contribution of amide coordination in the solid-state of the gold(III) complexes; however, the solution data suggests a high contribution from the neutral L-type resonance forms. This L-type contribution, primarily shown through cyclic voltammetry studies, prevents reversible gold(III) reduction and also disfavors abstraction of the ancillary chloride ligand. Furthermore, a novel macrocyclic-PYA ligand is introduced, which shows secondary metal-ligand interactions.
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Affiliation(s)
- Alexander J Bukvic
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Martin Albrecht
- Department of Chemistry, Biochemistry and Pharmaceutical Sciences, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland
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5
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Ritleng V, Michon C. Bidentate Donor-Functionalized N-Heterocyclic Carbenes: Valuable Ligands for Ruthenium-Catalyzed Transfer Hydrogenation. Molecules 2022; 27:molecules27154703. [PMID: 35897879 PMCID: PMC9329912 DOI: 10.3390/molecules27154703] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 07/20/2022] [Accepted: 07/21/2022] [Indexed: 11/23/2022] Open
Abstract
Ruthenium complexes are by far the most studied compounds that catalyze hydrogen transfer reactions. In this review, we describe the use in this field of ruthenium complexes bearing bidentate donor-functionalized N-heterocyclic carbene ligands. The review specifically covers the application in transfer hydrogenations of (κ2-CNHC,Y)-ruthenacyclic compounds where the Y donor atom is a N, P, O, or S atom, and where the N-heterocyclic carbene ligand is a classical imidazol-2-ylidene, a benzimidazol-2-ylidene, a mesoionic 1,2,3-triazolylidene, or an imidazol-4-ylidene ligand. Tridentate donor-functionalized N-heterocyclic carbene complexes thus fall outside the scope of the review. Applications in (asymmetric) transfer hydrogenation of ketones, aldehydes, imines, alkenes, and nitrobenzene are discussed.
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6
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Patra K, Laskar RA, Nath A, Bera JK. A Protic Mn(I) Complex Based on a Naphthyridine- N-oxide Scaffold: Protonation/Deprotonation Studies and Catalytic Applications for Alkylation of Ketones. Organometallics 2022. [DOI: 10.1021/acs.organomet.2c00085] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Kamaless Patra
- Department of Chemistry and Centre for Environmental Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Roshayed Ali Laskar
- Department of Chemistry and Centre for Environmental Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Anubhav Nath
- Department of Chemistry and Centre for Environmental Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
| | - Jitendra K. Bera
- Department of Chemistry and Centre for Environmental Science and Engineering, Indian Institute of Technology Kanpur, Kanpur 208016, India
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7
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Prakasham AP, Ta S, Dey S, Ghosh P. One pot tandem dual CC and CO bond reductions in the β-alkylation of secondary alcohols with primary alcohols by ruthenium complexes of amido and picolyl functionalized N-heterocyclic carbenes. Dalton Trans 2021; 50:15640-15654. [PMID: 34673856 DOI: 10.1039/d1dt02849a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Two different classes of ruthenium complexes, namely, [1-mesityl-3-(2,6-Me2-phenylacetamido)-imidazol-2-ylidene]Ru(p-cymene)Cl (1c) and {[1-(pyridin-2-ylmethyl)-3-(2,6-Me2-phenyl)-imidazol-2-ylidene]Ru(p-cymene)Cl}Cl (2c), successfully catalyzed the one-pot tandem alcohol-alcohol coupling reactions of a variety of secondary and primary alcohols, in moderate to good yields of ca. 63-89%. The mechanistic investigation performed on two representative catalytic substrates, 1-phenylethanol and benzyl alcohol using the neutral ruthenium (1c) complex showed that the catalysis proceeded via a partially reduced CC hydrogenated carbonyl species, [PhCOCH2CH2Ph] (3'), to the fully reduced CO and CC hydrogenated secondary alcohol, [PhCH(OH)CH2CH2Ph] (3). Furthermore, the time dependent study showed that the major product of the catalysis modulated between (3') and (3) during the catalysis run performed over an extended period of 120 hours. Finally, the practical utility of the alcohol-alcohol coupling reaction was demonstrated by preparing five different flavan derivatives (13-17) related to various bioactive flavonoid natural products, in a one-pot tandem fashion.
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Affiliation(s)
- A P Prakasham
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
| | - Sabyasachi Ta
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
| | - Shreyata Dey
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
| | - Prasenjit Ghosh
- Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai 400 076, India.
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8
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Huang M, Liu J, Li Y, Lan XB, Su P, Zhao C, Ke Z. Recent advances on N-heterocyclic carbene transition metal complexes for dehydrogenative catalysis using alcohols. Catal Today 2021. [DOI: 10.1016/j.cattod.2020.10.022] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
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9
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Munz D, Meyer K. Charge frustration in ligand design and functional group transfer. Nat Rev Chem 2021; 5:422-439. [PMID: 37118028 DOI: 10.1038/s41570-021-00276-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/25/2021] [Indexed: 02/08/2023]
Abstract
Molecules with different resonance structures of similar importance, such as heterocumulenes and mesoionics, are prominent in many applications of chemistry, including 'click chemistry', photochemistry, switching and sensing. In coordination chemistry, similar chameleonic/schizophrenic entities are referred to as ambidentate/ambiphilic or cooperative ligands. Examples of these had remained, for a long time, limited to a handful of archetypal compounds that were mere curiosities. In this Review, we describe ambiphilicity - or, rather, 'charge frustration' - as a general guiding principle for ligand design and functional group transfer. We first give a historical account of organic zwitterions and discuss their electronic structures and applications. Our discussion then focuses on zwitterionic ligands and their metal complexes, such as those of ylidic and redox-active ligands. Finally, we present new approaches to single-atom transfer using cumulated small molecules and outline emerging areas, such as bond activation and stable donor-acceptor ligand systems for reversible 1e- chemistry or switching.
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10
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Ó Máille GM, Dall'Anese A, Grossenbacher P, Montini T, Milani B, Albrecht M. Modulation of N^N'-bidentate chelating pyridyl-pyridylidene amide ligands offers mechanistic insights into Pd-catalysed ethylene/methyl acrylate copolymerisation. Dalton Trans 2021; 50:6133-6145. [PMID: 33973584 DOI: 10.1039/d1dt00389e] [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
The efficient copolymerisation of functionalised olefins with alkenes continues to offer considerable challenges to catalyst design. Based on recent work using palladium complexes containing a dissymmetric N^N'-bidentate pyridyl-PYA ligand (PYA = pyridylidene amide), which showed a high propensity to insert methyl acrylate, we have here modified this catalyst structure by inserting shielding groups either into the pyridyl fragment, or the PYA unit, or both to avoid fast β-hydrogen elimination. While a phenyl substituent at the pyridyl side impedes catalytic activity completely and leads to an off-cycle cyclometallation, the introduction of an ortho-methyl group on the PYA side of the N^N'-ligand was more prolific and doubled the catalytic productivity. Mechanistic investigations with this ligand system indicated the stabilisation of a 4-membered metallacycle intermediate at room temperature, which has previously been postulated and detected only at 173 K, but never observed at ambient temperature so far. This intermediate was characterised by solution NMR spectroscopy and rationalises, in part, the formation of α,β-unsaturated esters under catalytic conditions, thus providing useful principles for optimised catalyst design.
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Affiliation(s)
- Gearóid M Ó Máille
- Department of Chemistry & Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
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11
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Abdolla NSY, Davies DL, Singh K. Bis‐Cyclometallated Iridium(III) Complexes with Bidentate Ligands Containing One or Two Pyridylideneamine (PYE) Donors: Influence of PYE Substitution (
para
or
ortho
) on Complexation. Eur J Inorg Chem 2021. [DOI: 10.1002/ejic.202001054] [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)
- Noreldin S. Y. Abdolla
- School of Chemistry University of Leicester Leicester LE1 7RH UK
- Current address: Chemistry Department Faculty of Science Omar Al-Mukhtar University Tobruk Libya
| | - David L. Davies
- School of Chemistry University of Leicester Leicester LE1 7RH UK
| | - Kuldip Singh
- School of Chemistry University of Leicester Leicester LE1 7RH UK
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12
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Verhoeven DGA, Albrecht M. Modular O- vs. N-coordination of pyridylidene amide ligands to iron determines activity in alcohol oxidation catalysis. Dalton Trans 2020; 49:17674-17682. [PMID: 33232405 DOI: 10.1039/d0dt02818e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A family of polydentate pyridine-substituted pyridylidene amide (PYA) complexes bound to iron(ii) was developed. The variation of the coordination set from NN-bidentate PYA to tridentate pincer-type pyPYA2 systems (pyPYA2 = 2,6-bis(PYA)pyridine) had a large influence on the binding mode to iron(ii), including a change from the N- to rare O-coordination of the PYA site and a concomitant shift of the predominant ligand resonance structure. These binding mode variations invoke changes in the reactivity of the complexes, which were probed in the peroxide-mediated oxidation of 1-phenylethanol to acetophenone. A comparison with uncomplexed FeCl2 indicated that bidentate NN coordination is unstable and presumably leads to the dissociation of FeCl2. In contrast, the tridentate ligand binding is robust. Remarkably, the tridentate PYA pincer coordination inhibits catalytic activity in the NNN binding mode, while the ONO coordination greatly enhances catalytic performance. Under optimized conditions, the bis-ligated ONO pincer iron complex [Fe(pyPYA2)2][2PF6] reaches full conversion within one hour (0.5 mol% catalyst loading) and under dilute conditions turnover numbers over 20 000 (0.005 mol% catalyst loading).
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Affiliation(s)
- Dide G A Verhoeven
- Departement für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
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13
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Melle P, Thiede J, Hey DA, Albrecht M. Highly Efficient Transfer Hydrogenation Catalysis with Tailored Pyridylidene Amide Pincer Ruthenium Complexes. Chemistry 2020; 26:13226-13234. [PMID: 32452600 DOI: 10.1002/chem.202001145] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 05/25/2020] [Indexed: 11/09/2022]
Abstract
The rational optimization of homogeneous catalysts requires ligand platforms that are easily tailored to improve catalytic performance. Here, it is demonstrated that pyridylidene amides (PYAs) provide such a platform to custom-shape transfer hydrogenation catalysts with exceptional activity. Specifically, a series of meta-PYA pincer ligands with differently substituted PYA units has been synthezised and coordinated to ruthenium(II) centres to form bench-stable tris-acetonitrile complexes [Ru(R-PYA-pincer)(MeCN)3 ](PF6 )2 (R=OMe, Me, H, Cl, CF3 ). Analytic studies including 1 H NMR spectroscopy, cyclic voltammetry, and X-ray crystallography reveal a direct influence of the substituents on the electronic properties of the ruthenium center. The complexes are active in the catalytic transfer hydrogenation of ketones, with activities directly encoded by the PYA substitution pattern. Their perfomance improves further upon exchange of an ancillary MeCN ligand with PPh3 . While complexes [Ru(R-PYA-pincer)(PPh3 )(MeCN)2 ](PF6 )2 were only isolated for R=H, Me, an in situ protocol was developed to generate these complexes in situ for R=OMe, Cl, CF3 by using a 1:2 ratio of the complexes and PPh3 . This in situ protocol together with a short catalyst pre-activation provided highly active catalytic systems. The most active pre-catalyst featured the methoxy-substituted PYA ligand and reached turnover frenquencies of 210 000 h-1 under an exceptionally low catalyst loading of 25 ppm for the benchmark substrate benzophenone, representing one of the most active transfer hydrogenation systems known to date.
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Affiliation(s)
- Philipp Melle
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Jan Thiede
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
| | - Daniela A Hey
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland.,Fakultät für Chemie, Technische Universität München, Lichtenbergstrasse 4, 85748, Garching, Germany
| | - Martin Albrecht
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, 3012, Bern, Switzerland
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14
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Melle P, Ségaud N, Albrecht M. Ambidentate bonding and electrochemical implications of pincer-type pyridylidene amide ligands in complexes of nickel, cobalt and zinc. Dalton Trans 2020; 49:12662-12673. [PMID: 32959829 DOI: 10.1039/d0dt02482a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Pincer-type tridentate pyridyl bis(pyridylidene amide) (pyPYA2) ligand systems were coordinated to the Earth-abundant first row transition metals nickel, cobalt and zinc. A one-pot synthesis in water/ethanol afforded octahedral homoleptic bis-PYA complexes, [M(pyPYA2)2](PF6)2, whereas five-coordinate mono-PYA dichloride complexes, [M(pyPYA2)Cl2], were obtained upon slow addition of the ligand to the metal chlorides in DMF. Electrochemical measurements further revealed a facile oxidation of the metal centers from Ni2+ to Ni4+ and Co2+ to Co3+, respectively, while the Zn2+ system was redox inactive. These experiments further allowed for quantification of the much stronger electron donor properties of neutral N,N,N-tridentate pyPYA2 pincer ligands as compared to terpy. Remarkably, ortho-PYA pincer ligands feature amide coordination to the metal center via oxygen or nitrogen. This ambidentate ligand binding constitutes another mode of donor flexibility of the PYA ligand system, complementing the resonance structure dynamics established previously. NMR spectroscopic and MS analysis reveal that the meta-PYA ligand undergoes selective deuteration when coordinated to cobalt. This reactivity suggests the potential of this ligand as a transient proton reservoir for HX bond activation and, moreover, indicates the relevance of several resonance structures and therefore supports the notion that meta-PYA ligands are mesoionic.
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Affiliation(s)
- Philipp Melle
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
| | - Nathalie Ségaud
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
| | - Martin Albrecht
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland.
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15
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Huynh HV, Vossen JT. Donor Strength Determination of Pyridinylidene-amide Ligands using Their Palladium-NHC Complexes. Inorg Chem 2020; 59:12486-12493. [PMID: 32805994 DOI: 10.1021/acs.inorgchem.0c01585] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pyridinylidene-amides (PYAs) are a relatively new type of N-donor ligands that can exist in three isomeric forms and adopt various resonance structures. This makes them electronically flexible, and in order to evaluate their electronic profile using the Huynh electronic parameter (HEP), seven structurally diverse mixed N-heterocyclic carbenes (NHCs)/PYA palladium complexes of the type trans-[PdBr2(iPr2-bimy)(PYA)] were prepared and fully characterized by various spectroscopic and spectrometric methods. This study shows that PYAs are among the strongest, formally neutral N-donors, but they are still weaker than phosphines and organometallic ligands such as NHCs. Notably, the donating abilities of isomeric PYAs are distinct and can be further fine-tuned by the choice of two substituents making them structurally and electronically versatile. These characteristics and the ease of their preparation hold promise for a wide applicability in coordination chemistry.
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Affiliation(s)
- Han Vinh Huynh
- Department of Chemistry, National University of Singapore3 Science Drive 3, 117543 Singapore
| | - Jeroen Thomas Vossen
- Department of Chemistry, National University of Singapore3 Science Drive 3, 117543 Singapore
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16
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Navarro M, Segarra C, Pfister T, Albrecht M. Structural, Electronic, and Catalytic Modulation of Chelating Pyridylideneamide Ruthenium(II) Complexes. Organometallics 2020. [DOI: 10.1021/acs.organomet.0c00205] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Affiliation(s)
- Miquel Navarro
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Candela Segarra
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Tim Pfister
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Martin Albrecht
- Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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17
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Salzmann K, Segarra C, Albrecht M. Donor‐Flexible Bis(pyridylidene amide) Ligands for Highly Efficient Ruthenium‐Catalyzed Olefin Oxidation. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202002014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Kevin Salzmann
- Department of Chemistry and Biochemistry University of Bern Freiestrasse 3 3012 Bern Switzerland
| | - Candela Segarra
- Department of Chemistry and Biochemistry University of Bern Freiestrasse 3 3012 Bern Switzerland
| | - Martin Albrecht
- Department of Chemistry and Biochemistry University of Bern Freiestrasse 3 3012 Bern Switzerland
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18
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Weilhard A, Salzmann K, Navarro M, Dupont J, Albrecht M, Sans V. Catalyst design for highly efficient carbon dioxide hydrogenation to formic acid under buffering conditions. J Catal 2020. [DOI: 10.1016/j.jcat.2020.02.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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19
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Salzmann K, Segarra C, Albrecht M. Donor‐Flexible Bis(pyridylidene amide) Ligands for Highly Efficient Ruthenium‐Catalyzed Olefin Oxidation. Angew Chem Int Ed Engl 2020; 59:8932-8936. [DOI: 10.1002/anie.202002014] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Kevin Salzmann
- Department of Chemistry and Biochemistry University of Bern Freiestrasse 3 3012 Bern Switzerland
| | - Candela Segarra
- Department of Chemistry and Biochemistry University of Bern Freiestrasse 3 3012 Bern Switzerland
| | - Martin Albrecht
- Department of Chemistry and Biochemistry University of Bern Freiestrasse 3 3012 Bern Switzerland
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20
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Navarro M, Rosar V, Montini T, Milani B, Albrecht M. Olefin Dimerization and Isomerization Catalyzed by Pyridylidene Amide Palladium Complexes. Organometallics 2018. [DOI: 10.1021/acs.organomet.8b00422] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Miquel Navarro
- Department für Chemie und Biochemie, Universität Bern, CH−3012 Bern, Switzerland
| | - Vera Rosar
- Department für Chemie und Biochemie, Universität Bern, CH−3012 Bern, Switzerland
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, via Licio Giorgieri 1, 34127 Trieste, Italy
| | - Tiziano Montini
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, via Licio Giorgieri 1, 34127 Trieste, Italy
| | - Barbara Milani
- Department of Chemical and Pharmaceutical Sciences, University of Trieste, via Licio Giorgieri 1, 34127 Trieste, Italy
| | - Martin Albrecht
- Department für Chemie und Biochemie, Universität Bern, CH−3012 Bern, Switzerland
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21
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Melle P, Manoharan Y, Albrecht M. Modular Pincer-type Pyridylidene Amide Ruthenium(II) Complexes for Efficient Transfer Hydrogenation Catalysis. Inorg Chem 2018; 57:11761-11774. [DOI: 10.1021/acs.inorgchem.8b01895] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Philipp Melle
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Yanisha Manoharan
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Martin Albrecht
- Department für Chemie und Biochemie, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
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22
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Navarro M, Smith CA, Li M, Bernhard S, Albrecht M. Optimization of Synthetically Versatile Pyridylidene Amide Ligands for Efficient Iridium‐Catalyzed Water Oxidation. Chemistry 2018; 24:6386-6398. [DOI: 10.1002/chem.201705619] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Indexed: 01/08/2023]
Affiliation(s)
- Miquel Navarro
- Department of Chemistry & Biochemistry University of Bern Freiestrasse 3 3012 Bern Switzerland
| | - Christene A. Smith
- Department of Chemistry & Biochemistry University of Bern Freiestrasse 3 3012 Bern Switzerland
- Permanent address: Department of Chemistry Queen's University 90 Bader Lane Kingston Ontario Canada
| | - Mo Li
- Department of Chemistry Carnegie Mellon University 4400 Fifth Avenue Pittsburgh PA 15213 USA
| | - Stefan Bernhard
- Department of Chemistry Carnegie Mellon University 4400 Fifth Avenue Pittsburgh PA 15213 USA
| | - Martin Albrecht
- Department of Chemistry & Biochemistry University of Bern Freiestrasse 3 3012 Bern Switzerland
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23
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Navarro M, Li M, Bernhard S, Albrecht M. A mesoionic nitrogen-donor ligand: structure, iridium coordination, and catalytic effects. Dalton Trans 2018; 47:659-662. [PMID: 29239436 DOI: 10.1039/c7dt04555g] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A first example of a mesoionic ligand with a nitrogen coordination site was prepared by a simple and robust synthesis and is shown to have excellent properties for promoting iridium-catalyzed water oxidation.
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Affiliation(s)
- Miquel Navarro
- Department of Chemistry & Biochemistry
- University of Bern
- CH-3012 Bern
- Switzerland
| | - Mo Li
- Department of Chemistry
- Carnegie Mellon University
- Pittsburgh
- USA
| | - Stefan Bernhard
- Department of Chemistry
- Carnegie Mellon University
- Pittsburgh
- USA
| | - Martin Albrecht
- Department of Chemistry & Biochemistry
- University of Bern
- CH-3012 Bern
- Switzerland
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24
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Gonçalves TP, Huang KW. Metal–Ligand Cooperative Reactivity in the (Pseudo)-Dearomatized PNx(P) Systems: The Influence of the Zwitterionic Form in Dearomatized Pincer Complexes. J Am Chem Soc 2017; 139:13442-13449. [DOI: 10.1021/jacs.7b06305] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Théo P. Gonçalves
- KAUST Catalysis Center and
Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
| | - Kuo-Wei Huang
- KAUST Catalysis Center and
Division of Physical Sciences and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Saudi Arabia
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25
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Navarro M, Smith CA, Albrecht M. Enhanced Catalytic Activity of Iridium(III) Complexes by Facile Modification of C,N-Bidentate Chelating Pyridylideneamide Ligands. Inorg Chem 2017; 56:11688-11701. [PMID: 28898071 DOI: 10.1021/acs.inorgchem.7b01654] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A set of aryl-substituted pyridylideneamide (PYA) ligands with variable donor properties owing to a pronounced zwitterionic and a neutral diene-type resonance structure were used as electronically flexible ligands at a pentamethylcyclopentadienyl (Cp*) iridium center. The straightforward synthesis of this type of ligand allows for an easy incorporation of donor substituents such as methoxy groups in different positions of the phenyl ring of the C,N-bidentate chelating PYA. These modifications considerably enhance the catalytic activity of the coordinated iridium center toward the catalytic aerobic transfer hydrogenation of carbonyls and imines as well as the hydrosilylation of phenylacetylene. Moreover, these PYA iridium complexes catalyze the base-free transfer hydrogenation of aldehydes, and to a lesser extent also of ketones. Under standard transfer hydrogenation conditions including base, aldehydes are rapidly oxidized to carboxylic acids rather than reduced to the corresponding alcohol, as is observed under base-free conditions.
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Affiliation(s)
- Miquel Navarro
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Christene A Smith
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Martin Albrecht
- Department of Chemistry and Biochemistry, University of Bern , Freiestrasse 3, CH-3012 Bern, Switzerland
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26
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Chen C, Ni S, Zheng Q, Yu M, Wang H. Synthesis, Structure, Biological Evaluation, and Catalysis of Two Pyrazole-Functionalized NHC-RuIIComplexes. Eur J Inorg Chem 2017. [DOI: 10.1002/ejic.201601116] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Chao Chen
- College of Life Sciences; Huzhou University; East 2nd Road 313000 Huzhou China
| | - Shengliang Ni
- College of Life Sciences; Huzhou University; East 2nd Road 313000 Huzhou China
| | - Qing Zheng
- College of Life Sciences; Huzhou University; East 2nd Road 313000 Huzhou China
| | - Meifang Yu
- College of Life Sciences; Huzhou University; East 2nd Road 313000 Huzhou China
| | - Hangxiang Wang
- The First Affiliated Hospital; School of Medicine; Zhejiang University; 310003 Hangzhou China
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27
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Navarro M, Wang S, Müller-Bunz H, Redmond G, Farràs P, Albrecht M. Triazolylidene Metal Complexes Tagged with a Bodipy Chromophore: Synthesis and Monitoring of Ligand Exchange Reactions. Organometallics 2017. [DOI: 10.1021/acs.organomet.6b00672] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- Miquel Navarro
- Department für
Chemie und Biochemie, Universität Bern, CH−3012 Bern, Switzerland
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
| | - Suxiao Wang
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
| | - Helge Müller-Bunz
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
| | - Gareth Redmond
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
| | - Pau Farràs
- School of
Chemistry, NUI Galway, Galway, Ireland
| | - Martin Albrecht
- Department für
Chemie und Biochemie, Universität Bern, CH−3012 Bern, Switzerland
- School of Chemistry, University College Dublin, Belfield, Dublin 4, Ireland
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28
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Muller CM, Babak MV, Kubanik M, Hanif M, Jamieson SM, Hartinger CG, Wright LJ. Reprint of: Pt(II) pyridinium amidate (PYA) complexes: Preparation and in vitro anticancer activity studies. Inorganica Chim Acta 2017. [DOI: 10.1016/j.ica.2016.09.045] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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29
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Hollering M, Albrecht M, Kühn FE. Bonding and Catalytic Application of Ruthenium N-Heterocyclic Carbene Complexes Featuring Triazole, Triazolylidene, and Imidazolylidene Ligands. Organometallics 2016. [DOI: 10.1021/acs.organomet.6b00504] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Manuela Hollering
- Department of Chemistry & Catalysis Research Center, Molecular Catalysis, Technische Universität München, Lichtenbergstraße 4, D-85747 Garching bei München, Germany
- SC
XRD Laboratory, Catalysis Research Center, Technische Universität München, Ernst-Otto-Fischer-Straße 1, 85747 Garching bei München, Germany
| | - Martin Albrecht
- Department of Chemistry & Biochemistry, Universität Bern, Freiestrasse 3, CH-3012 Bern, Switzerland
| | - Fritz E. Kühn
- Department of Chemistry & Catalysis Research Center, Molecular Catalysis, Technische Universität München, Lichtenbergstraße 4, D-85747 Garching bei München, Germany
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30
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Muller CM, Babak MV, Kubanik M, Hanif M, Jamieson SM, Hartinger CG, Wright LJ. Pt(II) pyridinium amidate (PYA) complexes: Preparation and in vitro anticancer activity studies. Inorganica Chim Acta 2016. [DOI: 10.1016/j.ica.2016.05.025] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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31
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Gülcemal S, Gülcemal D, Whitehead GFS, Xiao J. Acceptorless Dehydrogenative Oxidation of Secondary Alcohols Catalysed by Cp*IrIII
-NHC Complexes. Chemistry 2016; 22:10513-22. [DOI: 10.1002/chem.201601648] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2016] [Indexed: 01/20/2023]
Affiliation(s)
- Süleyman Gülcemal
- Department of Chemistry; University of Liverpool; Liverpool L69 7ZD UK
- Department of Chemistry; Ege University; 35100 Bornova-Izmir Turkey
| | - Derya Gülcemal
- Department of Chemistry; University of Liverpool; Liverpool L69 7ZD UK
- Department of Chemistry; Ege University; 35100 Bornova-Izmir Turkey
| | | | - Jianliang Xiao
- Department of Chemistry; University of Liverpool; Liverpool L69 7ZD UK
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32
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Zafar MN, Nazar MF, Sumrra SH, Gul-E-Saba, Yasmin A, Atif AH. Development of some important nitrogen donor ligands for transition metal homogeneous catalysis. RUSS J COORD CHEM+ 2016. [DOI: 10.1134/s1070328416040072] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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33
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Navarro M, Li M, Müller-Bunz H, Bernhard S, Albrecht M. Donor-Flexible Nitrogen Ligands for Efficient Iridium-Catalyzed Water Oxidation Catalysis. Chemistry 2016; 22:6740-5. [DOI: 10.1002/chem.201600875] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2016] [Indexed: 11/07/2022]
Affiliation(s)
- Miquel Navarro
- Department of Chemistry & Biochemistry; University of Bern; Freiestrasse 3 3012 Bern Switzerland
- School of Chemistry and Chemical Biology; University College Dublin; Belfield Dublin 4 Ireland
| | - Mo Li
- Department of Chemistry; Carnegie Mellon University; 4400 Fifth Avenue Pittsburgh PA 15213 USA
| | - Helge Müller-Bunz
- School of Chemistry and Chemical Biology; University College Dublin; Belfield Dublin 4 Ireland
| | - Stefan Bernhard
- Department of Chemistry; Carnegie Mellon University; 4400 Fifth Avenue Pittsburgh PA 15213 USA
| | - Martin Albrecht
- Department of Chemistry & Biochemistry; University of Bern; Freiestrasse 3 3012 Bern Switzerland
- School of Chemistry and Chemical Biology; University College Dublin; Belfield Dublin 4 Ireland
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34
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Donnelly KF, Segarra C, Shao LX, Suen R, Müller-Bunz H, Albrecht M. Adaptive N-Mesoionic Ligands Anchored to a Triazolylidene for Ruthenium-Mediated (De)Hydrogenation Catalysis. Organometallics 2015. [DOI: 10.1021/acs.organomet.5b00533] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Affiliation(s)
- Kate F. Donnelly
- School
of Chemistry and Chemical Biology, University College Dublin, Belfied, Dublin
4, Ireland
| | - Candela Segarra
- School
of Chemistry and Chemical Biology, University College Dublin, Belfied, Dublin
4, Ireland
- Department
of Chemistry and Biochemistry, Universität Bern, Freiestrasse 3, 3012 Bern, Switzerland
| | - Li-Xiong Shao
- School
of Chemistry and Chemical Biology, University College Dublin, Belfied, Dublin
4, Ireland
| | - Rachelle Suen
- School
of Chemistry and Chemical Biology, University College Dublin, Belfied, Dublin
4, Ireland
| | - Helge Müller-Bunz
- School
of Chemistry and Chemical Biology, University College Dublin, Belfied, Dublin
4, Ireland
| | - Martin Albrecht
- School
of Chemistry and Chemical Biology, University College Dublin, Belfied, Dublin
4, Ireland
- Department
of Chemistry and Biochemistry, Universität Bern, Freiestrasse 3, 3012 Bern, Switzerland
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35
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Butschke B, Fillman KL, Bendikov T, Shimon LJW, Diskin-Posner Y, Leitus G, Gorelsky SI, Neidig ML, Milstein D. How Innocent are Potentially Redox Non-Innocent Ligands? Electronic Structure and Metal Oxidation States in Iron-PNN Complexes as a Representative Case Study. Inorg Chem 2015; 54:4909-26. [DOI: 10.1021/acs.inorgchem.5b00509] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
| | - Kathlyn L. Fillman
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | | | | | | | | | - Serge I. Gorelsky
- Centre for Catalysis Research and Innovation, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada
| | - Michael L. Neidig
- Department of Chemistry, University of Rochester, Rochester, New York 14627, United States
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36
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Albrecht M. Normal and Abnormal N-Heterocyclic Carbene Ligands. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2014. [DOI: 10.1016/b978-0-12-800976-5.00002-3] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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