Efficient Nicotinamide Adenine Dinucleotide Regeneration with a Rhodium–Carbene Catalyst and Isolation of a Hydride Intermediate

Ganesan, V.; Kim, Jennifer Juhyun; Shin, Jeongcheol; Park, Kiyoung; Yoon, Sungho

doi:10.1021/acs.inorgchem.2c00059

Cited by 9 publications

(12 citation statements)

References 69 publications

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“…The 13 C{ 1 H} NMR spectra of the presented complexes show characteristic doublet signals in the range of 170-160 MHz with Rh-MIC coupling constants between J Rh;MIC = 53-48 Hz. [24,33] In the molecular structures in the crystal, the rhodium center in the complexes [Rh [34] The complexes show a η 5 mode from the Cp* ligand to the rhodium center with a metal-carbon bond length between 2.136(4)-2. [34] In contrast, an almost orthogonal geometry of the Cp* plane and the plane within the pyridyl-MIC coordination pocket (C1-N1-C4-N4) are observed in [Rh(CÀ N)H](PF 6 ) and [Rh(CÀ N)] (Figure 1).…”

Section: Synthesis and Characterizationmentioning

confidence: 99%

“…Recently, a [RhCp*] hydride complexes with a bis-NHC ligand (NHC = N-heterocyclic carbene) has been reported for the catalytic reduction of NAD + to NADH (= nicotinamide adenine dinucleotide) and crystallographically characterized. [24] However, very little information is available on their isolation and characterization, in particular with single crystal X-ray diffraction, and reactivity studies of such intermediates for complexes of pyridyl-MIC containing ligands. [25] The ligands (CÀ C = pyridyl-4-triazolylidene [26] and CÀ N = pyridyl-1-triazolylidene) [27] presented in this work show similar overall pÀ acceptor properties and a highly increased overall sÀ donor strength compared to the well-established bpy ligand.…”

Section: Introductionmentioning

confidence: 99%

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Isolation, Characterization and Reactivity of Key Intermediates Relevant to Reductive (Electro)catalysis with Cp*Rh Complexes Containing Pyridyl‐MIC (MIC=Mesoionic Carbene) Ligands

Bens,

Walter,

Beerhues

et al. 2023

Chemistry A European J

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In recent years, metal complexes of pyridyl‐mesoionic carbene (MIC) ligands have been reported as excellent homogeneous and molecular electrocatalysts. In combination with group 9 metals, such ligands form highly active catalysts for hydrogenation/transfer hydrogenation/hydrosilylation catalysis and electrocatalysts for dihydrogen production. Despite such progress, very little is known about the structural/electrochemical/spectroscopic properties of crucial intermediates for such catalytic reactions with these ligands: solvato complexes, reduced complexes and hydridic species. We present here a comprehensive study involving the isolation, crystallographic characterization, electrochemical/spectroelectrochemical/theoretical investigations, and in‐situ reactivity studies of all the aforementioned crucial intermediates involving Cp*Rh and pyridyl‐MIC ligands. A detailed mechanistic study of the precatalytic activation of [RhCp*] complexes with pyridyl‐MIC ligands is presented. Intriguingly, amphiphilicity of the [RhCp*]‐hydride complexes was observed, displaying the substrate dependent transfer of H+, H∙ or H−. To the best of our knowledge, this study is the first of its kind targeting intermediates and reactive species involving metal complexes of pyridyl‐MIC ligands and investigating the interconversion amongst them.

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Section: Synthesis and Characterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Isolation, Characterization and Reactivity of Key Intermediates Relevant to Reductive (Electro)catalysis with Cp*Rh Complexes Containing Pyridyl‐MIC (MIC=Mesoionic Carbene) Ligands

Bens,

Walter,

Beerhues

et al. 2023

Chemistry A European J

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“…24 Finally, in 2022, Yoon et al described a water-soluble carbene rhodium complex of formula [(η 5 -Cp*)Rh(MDI)Cl] + [MDI = 1,1′methylenebis(3,3′-dimethylimidazolium)] (Figure 1) as a catalyst for the reduction of NAD + to NADH, highlighting the evidence for the formation of a stable metal-hydride intermediate upon its isolation and characterization. 25 When studying the catalytic activity and cycle of [(Cp*)-Rh(bipy)Cl] + , Fish et al described the possibility of a reverse reaction, where NADH is oxidized to NAD + via the formation of a hydride complex. 7 Later, in 2012, Ru(II)-arene complexes containing bipyridyl bidentate ligands (Figure 1) were shown to oxidize NADH to generate NAD + .…”

Section: ■ Introductionmentioning

confidence: 99%

“…Interestingly, Pizarro et al reported on Os(II) complexes bearing picolinate N,O-chelates and studied their reactivity toward catalytic TH of pyruvate, producing quantifiable excess lactate inside cancer cells when using formate as the hydride source . Finally, in 2022, Yoon et al described a water-soluble carbene rhodium complex of formula [(η 5 -Cp*)Rh(MDI)Cl] + [MDI = 1,1′-methylenebis(3,3′-dimethylimidazolium)] (Figure ) as a catalyst for the reduction of NAD + to NADH, highlighting the evidence for the formation of a stable metal-hydride intermediate upon its isolation and characterization …”

Section: Introductionmentioning

confidence: 99%

Beyond Metal-Arenes: Monocarbonyl Ruthenium(II) Catalysts for Transfer Hydrogenation Reactions in Water and in Cells

Lovison,

Berghausen,

Thomas

et al. 2023

ACS Catal.

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With the aim to design water-soluble organometallic Ru(II) complexes acting as anticancer agents catalyzing transfer hydrogenation (TH) reactions with biomolecules, we have synthesized four Ru(II) monocarbonyl complexes (1–4), featuring the 1,4-bis(diphenylphosphino)butane (dppb) ligand and different bidentate nitrogen (N∧N) ligands, of general formula [Ru(OAc)CO(dppb)(N∧N)] n (n = +1, 0; OAc = acetate). The compounds have been characterized by different methods, including 1H and 31P NMR spectroscopies, electrochemistry, as well as single-crystal X-ray diffraction in the case of 1 and 4. The compounds have also been studied for their hydrolysis in an aqueous environment and for the catalytic regioselective reduction of nicotinamide adenine dinucleotide (NAD+) to 1,4-dihydronicotinamide adenine dinucleotide (1,4-NADH) in aqueous solution with sodium formate as a hydride source. Moreover, the stoichiometric and catalytic oxidation of 1,4-NADH have also been investigated by UV–visible spectrophotometry and NMR spectroscopy. The results suggest that the catalytic cycle can start directly from the intact Ru(II) compound or from its aquo/hydroxo species (in the case of 1–3) to afford the hydride ruthenium complex. Overall, initial structure–activity relationships could be inferred which point toward the influence of the extension of the aromatic N∧N ligand in the cationic complexes 1–3 on TH in both reduction/oxidation processes. While complex 3 is the most active in TH from NADH to O2, the neutral complex 4, featuring a picolinamidate N∧N ligand, stands out as the most active catalyst for the reduction of NAD+, while being completely inactive toward NADH oxidation. The compound can also convert pyruvate into lactate in the presence of formate, albeit with scarce efficiency. In any case, for all compounds, Ru(II) hydride intermediates could be observed and even isolated in the case of complexes 1–3. Together, insights from the kinetic and electrochemical characterization suggest that, in the case of Ru(II) complexes 1–3, catalytic NADH oxidation sees the H-transfer from 1,4-NADH as the rate-limiting step, whereas for NAD+ hydrogenation with formate as the H-donor, the rate-limiting step is the transfer of the ruthenium hydride to the NAD+ substrate, as also suggested by density functional theory (DFT) calculations. Compound 4, stable with respect to hydrolysis in aqueous solution, appears to operate via a different mechanism with respect to the other derivatives. Finally, the anticancer activity and ability to form reactive oxygen species (ROS) of complexes 1–3 have been studied in cancerous and nontumorigenic cells in vitro. Noteworthy, the conversion of aldehydes to alcohols could be achieved by the three Ru(II) catalysts in living cells, as assessed by fluorescence microscopy. Furthermore, the formation of Ru(II) hydride intermediate upon treatment of cancer cell extracts with complex 3 has been detected by 1H NMR spectroscopy. Overall, this study paves the way to the application of non-arene-based org...

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“…Finally, in 2022, Sungho Yoon et al described a water-soluble carbene rhodium complex of formula [(η 5 -Cp*)Rh(MDI)Cl] + [MDI = 1,1′-methylenebis(3,3′-dimethylimidazolium)] (Figure 1) as catalyst for the reduction of NAD + to NADH, highlighting the evidence of the formation of a stable metal hydride intermediate upon its isolation and characterization. 18 When studying the catalytic activity and cycle of [(Cp*)Rh(bipy)Cl] + , Fish et al described the possibility of a reverse reaction, where NADH is oxidized to NAD + via formation of a hydride complex 3 . Later in 2012, Ru(II)-arene complexes containing bipyridyl bidentate ligands (Figure 1) were shown to oxidize NADH to generate NAD + 19 .…”

Section: Introductionmentioning

confidence: 99%

Beyond Metal-Arenes: Monocarbonyl Ruthenium(II) Catalysts for Transfer Hydrogenation Reactions in Cancer Cells

Lovison

Berghausen

Thomas

et al. 2023

Preprint

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With the aim to design new water-soluble organometallic Ru(II) complexes acting as anticancer agents catalysing transfer hydrogenation (TH) reactions with biomolecules, we have synthesized four Ru(II) monocarbonyl complexes (1-4) featuring the 1,4-bis(diphenylphosphino)butane (dppb) ligand and different bidentate nitrogen (N^N) ligands, of general formula [Ru(OAc)CO(dppb)(N^N)]n (n = +1, 0; OAc = acetate). The compounds have been characterised by different methods, including 1H and 31P NMR spectroscopy, electrochemistry as well as single crystals X-ray diffraction in the case of 1 and 4. The compounds have also been studied for their hydrolysis in aqueous environment, and for the catalytic regioselective reduction of NAD+ to 1,4-NADH in aqueous solution with sodium formate as hydride source. Moreover, the stoichiometric and catalytic oxidation of 1,4-NADH have also been investigated by UV-Visible spectrophotometry and NMR spectroscopy. Overall, initial structure-activity relationships could be inferred which point towards the influence of the extension of the aromatic N^N ligand in the cationic complexes 1-3 on the TH in both reduction/oxidation processes. The neutral complex 4, featuring a picolinamidate N^N ligand, stands out as the most active catalyst for the reduction of NAD+, while being completely inactive towards NADH oxidation. The compound can also convert pyruvate into lactate in the presence of formate, albeit with scarce efficiency. In any case, for all compounds, Ru(II) hydride intermediates could be observed and even isolated in the case of complexes 1-3. Together, insight from the kinetic and electrochemical characterization suggests that, in the case of Ru(II) complexes 1-3, catalytic NADH oxidation sees the H-transfer from 1,4-NADH as the rate limiting step, whereas for NAD+ hydrogenation with formate as the H-donor, the rate limiting step is the transfer of the ruthenium hydride to the NAD+ substrate. The latter is further modulated by the presence of di-cationic aquo- or mono-cationic hydroxo-species of complexes 1-3. Instead, compound 4, stable with respect to hydrolysis in aqueous solution, appears to operate via a different mechanism. Finally, the anticancer activity and ability to form reactive oxygen species (ROS) of complexes 1-3 have been studied in cancerous and non-tumorigenic cells in vitro. Noteworthy, the conversion of aldehydes to alcohols could be achieved by the three Ru(II) catalysts in living cells, as assessed by fluorescence microscopy. Furthermore, the formation of Ru(II) hydride intermediate upon treatment of cancer cell extracts with complex 3 has been detected by 1H NMR spectroscopy. Overall, this study paves the way to the application of non-arene based organometallic complexes as TH catalysts in biological environment.

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Efficient Nicotinamide Adenine Dinucleotide Regeneration with a Rhodium–Carbene Catalyst and Isolation of a Hydride Intermediate

Cited by 9 publications

References 69 publications

Isolation, Characterization and Reactivity of Key Intermediates Relevant to Reductive (Electro)catalysis with Cp*Rh Complexes Containing Pyridyl‐MIC (MIC=Mesoionic Carbene) Ligands

Isolation, Characterization and Reactivity of Key Intermediates Relevant to Reductive (Electro)catalysis with Cp*Rh Complexes Containing Pyridyl‐MIC (MIC=Mesoionic Carbene) Ligands

Beyond Metal-Arenes: Monocarbonyl Ruthenium(II) Catalysts for Transfer Hydrogenation Reactions in Water and in Cells

Beyond Metal-Arenes: Monocarbonyl Ruthenium(II) Catalysts for Transfer Hydrogenation Reactions in Cancer Cells

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