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Prasanta Ghosh - One of the best experts on this subject based on the ideXlab platform.
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A Diruthenium Complex of an N-Pyridyl-o-Aminophenol Derivative: A Route to Mixed Valency.
Chemistry (Weinheim an der Bergstrasse Germany), 2019Co-Authors: Debarpan Dutta, Suman Kundu, Prasanta GhoshAbstract:An N-pyridyl-o-Aminophenol Derivative that stabilises mixed-valence states of ruthenium ions is disclosed. A diruthenium complex, [(LIQ 0 )Ru2 Cl5 ]⋅MeOH (1⋅MeOH) is successfully isolated, in which LIQ 0 is the o-iminobenzoquinone form of 2-[(3-nitropyridin-2-yl)amino]phenol (LAP H2 ). In 1, LIQ 0 oriented towards one ruthenium centre is a non-innocent NO-donor redox ligand, whereas another oriented towards another ruthenium centre is an innocent pyridine-donor redox ligand. Complex 1 is a diruthenium(II,III) mixed-valence complex, [RuII (LIQ 0 )(μ-Cl)2 RuIII ], with a minor contribution from the diruthenium(III,III) state. [RuIII (LISQ .- )(μ-Cl)2 RuIII ] contains LISQ .- , which is the o-iminobenzosemiquinonate anion radical form of the ligand. Complexes 1- and 1+ are diruthenium(II,II), [RuII (LIQ 0 )(μ-Cl)2 RuII ], and diruthenium(III,III), [RuIII (LIQ 0 )(μ-Cl)2 RuIII ], complexes, respectively, of LIQ 0 . Complex 12- is a diruthenium(II,II) complex of the o-iminobenzosemiquinonate anion radical (LISQ .- ), [RuII (LISQ .- )(μ-Cl)2 RuII ], with a minor contribution from the diruthenium(III,II) form, [RuIII (LAP 2- )(μ-Cl)2 RuII ]. Complex 12+ is a diruthenium(III,IV) mixed-valence complex of LIQ 0 , [RuIII (LIQ 0 )(μ-Cl)2 RuIV ]. Complexes 1 and 12+ exhibit inter-valence charge-transfer transitions at λ=1300 and 1370 nm, respectively.
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cobalt ion promoted redox cascade a route to spiro oxazine oxazepine Derivatives and a dinuclear cobalt iii complex of an n 1 4 naphthoquinone o Aminophenol Derivative
Inorganic Chemistry, 2017Co-Authors: Sandip Mondal, Sachinath Bera, Suvendu Maity, Prasanta GhoshAbstract:The study discloses that the redox activity of N-(1,4-naphthoquinone)-o-Aminophenol Derivatives (LRH2) containing a (phenol)-NH-(1,4-naphthoquinone) fragment is notably different from that of a (phenol)-NH-(phenol) precursor. The former is a platform for a redox cascade. LRH2 is redox noninnocent and exists in Cat-N-(1,4-naphthoquinone)(2−) (LR 2–) and SQ-N-(1,4-naphthoquinone) (LR •–) states in the complexes. Reactions of LRH2 with cobalt(II) salts in MeOH in air promote a cascade affording spiro oxazine-oxazepine Derivatives (OXLR) in good yields, when R = H, Me, tBu. Spiro oxazine-oxazepine Derivatives are bioactive, and such a molecule has so far not been isolated by a schematic route. In this context this cascade is significant. Dimerization of LRH2 → OXLR in MeOH is a (6H+ + 6e) oxidation reaction and is composed of formations of four covalent bonds and 6-exo-trig and 7-endo-trig cyclization based on C–O coupling reactions, where MeOH is the source of a proton and the ester function. It was establis...
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Cobalt Ion Promoted Redox Cascade: A Route to Spiro Oxazine-Oxazepine Derivatives and a Dinuclear Cobalt(III) Complex of an N‑(1,4-Naphthoquinone)‑o‑Aminophenol Derivative
2017Co-Authors: Sandip Mondal, Sachinath Bera, Suvendu Maity, Prasanta GhoshAbstract:The study discloses that the redox activity of N-(1,4-naphthoquinone)-o-Aminophenol Derivatives (LRH2) containing a (phenol)-NH-(1,4-naphthoquinone) fragment is notably different from that of a (phenol)-NH-(phenol) precursor. The former is a platform for a redox cascade. LRH2 is redox noninnocent and exists in Cat-N-(1,4-naphthoquinone)(2−) (LR 2–) and SQ-N-(1,4-naphthoquinone) (LR •–) states in the complexes. Reactions of LRH2 with cobalt(II) salts in MeOH in air promote a cascade affording spiro oxazine-oxazepine Derivatives (OXLR) in good yields, when R = H, Me, tBu. Spiro oxazine-oxazepine Derivatives are bioactive, and such a molecule has so far not been isolated by a schematic route. In this context this cascade is significant. Dimerization of LRH2 → OXLR in MeOH is a (6H+ + 6e) oxidation reaction and is composed of formations of four covalent bonds and 6-exo-trig and 7-endo-trig cyclization based on C–O coupling reactions, where MeOH is the source of a proton and the ester function. It was established that the active cascade precursor is [(LMe •–)CoIIICl2] (A). Notably, formation of a spiro Derivative was not detected in CH3CN and the reaction ends up furnishing A. The route of the reaction is tunable by R, when R = NO2, it is a (2e + 4H+) oxidation reaction affording a dinuclear LR 2– complex of cobalt(III) of the type [(LNO2 2–)2CoIII2(OMe)2(H2O)2] (1) in good yields. No cascade occurs with zinc(II) ion even in MeOH and produces a LMe •– complex of type [(LMe •–)ZnIICl2] (2). The intermediate A and 2 exhibit strong EPR signals at g = 2.008 and 1.999, confrming the existence of LMe •– coordinated to low-spin cobalt(III) and zinc(II) ions. The intermediates of LRH2 → OXLR conversion were analyzed by ESI mass spectrometry. The molecular geometries of OXLR and 1 were confirmed by X-ray crystallography, and the spectral features were elucidated by TD DFT calculations
Rabindra Nath Mukherjee - One of the best experts on this subject based on the ideXlab platform.
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Probing the electronic structure of [Ru(L1)2]Z (z = 0, 1+ and 2+) (H2L1: a tridentate 2-Aminophenol Derivative) complexes in three ligand redox levels
Dalton transactions (Cambridge England : 2003), 2020Co-Authors: Anannya Saha, Amit Rajput, Puneet Gupta, Rabindra Nath MukherjeeAbstract:Aerobic reaction between [RuII(DMSO)4Cl2], a redox-active 2-Aminophenol-based ligand (H2L1: 2-[2-(benzylthio)phenylamino]-4,6-di-tert-butylphenol) and Et3N in MeOH under refluxing conditions afforded a purple complex [Ru(L1)2] (S = 0). Structural analysis reveals that the tridentate ligand coordinates in a mer conformation providing a distorted octahedral RuN2O2S2 coordination. Cyclic voltammetry on 1 in CH2Cl2 reveals the accessability of the monocation, dication and monoanion forms. Reddish purple monocation [Ru(L1)2](PF6)·CH2Cl2 ([1OX1](PF6)·CH2Cl2; S = 1/2) and green dication [Ru(L1)2](BF4)2·H2O ([1OX2](BF4)2·H2O; S = 0) have been isolated through the chemical oxidation of 1 in CH2Cl2 by [FeIII(η5-C5H5)2](PF6) and AgBF4, respectively. A structural analysis of the single crystals of the monocation and the dication with the compositions [1OX1](PF6)·CH2Cl2·H2O (2) and [1OX2](BF4)2·1.7H2O (3), respectively, has been done. Metrical (metal–ligand and ligand backbone) parameters, values of metrical oxidation states of coordinated ligands, 1H NMR spectra of 1 and [1OX2](BF4)2·H2O, EPR spectra of [1OX1](PF6)·CH2Cl2, X-ray photoelectron and UV-VIS-NIR spectra of 1–3, spin population analysis from broken-symmetry (BS) density functional theory (DFT) calculations and quasi-restricted orbital (QRO) analysis have allowed us to assign the electronic structure of the complexes. The complexes exhibit highly covalent metal–ligand interactions. The electronic states of 1, [1OX1]1+ and [1OX2]2+ are best described as [RuII{(LISQ)˙−}2] ↔ [RuIII{(LAP)2−}{(LISQ)˙−}] (S = 0), [RuIII{(LISQ)˙−}2]1+ (S = 1/2) and [RuII{(LIBQ)0}2]2+ ↔ [RuIII{(LISQ)˙−}{(LIBQ)0}]2+ (S = 0), respectively. Notably, all redox processes are ligand-centred. Absorption spectral properties have been rationalized based on time-dependent (TD)-DFT calculations. For 1, the appearance of an IVCT band at 1100 nm supports its Class II–III (borderline) ligand-based mixed-valence character.
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probing the electronic structure of ru l1 2 z z 0 1 and 2 h2l1 a tridentate 2 Aminophenol Derivative complexes in three ligand redox levels
Dalton Transactions, 2020Co-Authors: Anannya Saha, Amit Rajput, Puneet Gupta, Rabindra Nath MukherjeeAbstract:Aerobic reaction between [RuII(DMSO)4Cl2], a redox-active 2-Aminophenol-based ligand (H2L1: 2-[2-(benzylthio)phenylamino]-4,6-di-tert-butylphenol) and Et3N in MeOH under refluxing conditions afforded a purple complex [Ru(L1)2] (S = 0). Structural analysis reveals that the tridentate ligand coordinates in a mer conformation providing a distorted octahedral RuN2O2S2 coordination. Cyclic voltammetry on 1 in CH2Cl2 reveals the accessability of the monocation, dication and monoanion forms. Reddish purple monocation [Ru(L1)2](PF6)·CH2Cl2 ([1OX1](PF6)·CH2Cl2; S = 1/2) and green dication [Ru(L1)2](BF4)2·H2O ([1OX2](BF4)2·H2O; S = 0) have been isolated through the chemical oxidation of 1 in CH2Cl2 by [FeIII(η5-C5H5)2](PF6) and AgBF4, respectively. A structural analysis of the single crystals of the monocation and the dication with the compositions [1OX1](PF6)·CH2Cl2·H2O (2) and [1OX2](BF4)2·1.7H2O (3), respectively, has been done. Metrical (metal–ligand and ligand backbone) parameters, values of metrical oxidation states of coordinated ligands, 1H NMR spectra of 1 and [1OX2](BF4)2·H2O, EPR spectra of [1OX1](PF6)·CH2Cl2, X-ray photoelectron and UV-VIS-NIR spectra of 1–3, spin population analysis from broken-symmetry (BS) density functional theory (DFT) calculations and quasi-restricted orbital (QRO) analysis have allowed us to assign the electronic structure of the complexes. The complexes exhibit highly covalent metal–ligand interactions. The electronic states of 1, [1OX1]1+ and [1OX2]2+ are best described as [RuII{(LISQ)˙−}2] ↔ [RuIII{(LAP)2−}{(LISQ)˙−}] (S = 0), [RuIII{(LISQ)˙−}2]1+ (S = 1/2) and [RuII{(LIBQ)0}2]2+ ↔ [RuIII{(LISQ)˙−}{(LIBQ)0}]2+ (S = 0), respectively. Notably, all redox processes are ligand-centred. Absorption spectral properties have been rationalized based on time-dependent (TD)-DFT calculations. For 1, the appearance of an IVCT band at 1100 nm supports its Class II–III (borderline) ligand-based mixed-valence character.
Sandip Mondal - One of the best experts on this subject based on the ideXlab platform.
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cobalt ion promoted redox cascade a route to spiro oxazine oxazepine Derivatives and a dinuclear cobalt iii complex of an n 1 4 naphthoquinone o Aminophenol Derivative
Inorganic Chemistry, 2017Co-Authors: Sandip Mondal, Sachinath Bera, Suvendu Maity, Prasanta GhoshAbstract:The study discloses that the redox activity of N-(1,4-naphthoquinone)-o-Aminophenol Derivatives (LRH2) containing a (phenol)-NH-(1,4-naphthoquinone) fragment is notably different from that of a (phenol)-NH-(phenol) precursor. The former is a platform for a redox cascade. LRH2 is redox noninnocent and exists in Cat-N-(1,4-naphthoquinone)(2−) (LR 2–) and SQ-N-(1,4-naphthoquinone) (LR •–) states in the complexes. Reactions of LRH2 with cobalt(II) salts in MeOH in air promote a cascade affording spiro oxazine-oxazepine Derivatives (OXLR) in good yields, when R = H, Me, tBu. Spiro oxazine-oxazepine Derivatives are bioactive, and such a molecule has so far not been isolated by a schematic route. In this context this cascade is significant. Dimerization of LRH2 → OXLR in MeOH is a (6H+ + 6e) oxidation reaction and is composed of formations of four covalent bonds and 6-exo-trig and 7-endo-trig cyclization based on C–O coupling reactions, where MeOH is the source of a proton and the ester function. It was establis...
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Cobalt Ion Promoted Redox Cascade: A Route to Spiro Oxazine-Oxazepine Derivatives and a Dinuclear Cobalt(III) Complex of an N‑(1,4-Naphthoquinone)‑o‑Aminophenol Derivative
2017Co-Authors: Sandip Mondal, Sachinath Bera, Suvendu Maity, Prasanta GhoshAbstract:The study discloses that the redox activity of N-(1,4-naphthoquinone)-o-Aminophenol Derivatives (LRH2) containing a (phenol)-NH-(1,4-naphthoquinone) fragment is notably different from that of a (phenol)-NH-(phenol) precursor. The former is a platform for a redox cascade. LRH2 is redox noninnocent and exists in Cat-N-(1,4-naphthoquinone)(2−) (LR 2–) and SQ-N-(1,4-naphthoquinone) (LR •–) states in the complexes. Reactions of LRH2 with cobalt(II) salts in MeOH in air promote a cascade affording spiro oxazine-oxazepine Derivatives (OXLR) in good yields, when R = H, Me, tBu. Spiro oxazine-oxazepine Derivatives are bioactive, and such a molecule has so far not been isolated by a schematic route. In this context this cascade is significant. Dimerization of LRH2 → OXLR in MeOH is a (6H+ + 6e) oxidation reaction and is composed of formations of four covalent bonds and 6-exo-trig and 7-endo-trig cyclization based on C–O coupling reactions, where MeOH is the source of a proton and the ester function. It was established that the active cascade precursor is [(LMe •–)CoIIICl2] (A). Notably, formation of a spiro Derivative was not detected in CH3CN and the reaction ends up furnishing A. The route of the reaction is tunable by R, when R = NO2, it is a (2e + 4H+) oxidation reaction affording a dinuclear LR 2– complex of cobalt(III) of the type [(LNO2 2–)2CoIII2(OMe)2(H2O)2] (1) in good yields. No cascade occurs with zinc(II) ion even in MeOH and produces a LMe •– complex of type [(LMe •–)ZnIICl2] (2). The intermediate A and 2 exhibit strong EPR signals at g = 2.008 and 1.999, confrming the existence of LMe •– coordinated to low-spin cobalt(III) and zinc(II) ions. The intermediates of LRH2 → OXLR conversion were analyzed by ESI mass spectrometry. The molecular geometries of OXLR and 1 were confirmed by X-ray crystallography, and the spectral features were elucidated by TD DFT calculations
Anannya Saha - One of the best experts on this subject based on the ideXlab platform.
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Probing the electronic structure of [Ru(L1)2]Z (z = 0, 1+ and 2+) (H2L1: a tridentate 2-Aminophenol Derivative) complexes in three ligand redox levels
Dalton transactions (Cambridge England : 2003), 2020Co-Authors: Anannya Saha, Amit Rajput, Puneet Gupta, Rabindra Nath MukherjeeAbstract:Aerobic reaction between [RuII(DMSO)4Cl2], a redox-active 2-Aminophenol-based ligand (H2L1: 2-[2-(benzylthio)phenylamino]-4,6-di-tert-butylphenol) and Et3N in MeOH under refluxing conditions afforded a purple complex [Ru(L1)2] (S = 0). Structural analysis reveals that the tridentate ligand coordinates in a mer conformation providing a distorted octahedral RuN2O2S2 coordination. Cyclic voltammetry on 1 in CH2Cl2 reveals the accessability of the monocation, dication and monoanion forms. Reddish purple monocation [Ru(L1)2](PF6)·CH2Cl2 ([1OX1](PF6)·CH2Cl2; S = 1/2) and green dication [Ru(L1)2](BF4)2·H2O ([1OX2](BF4)2·H2O; S = 0) have been isolated through the chemical oxidation of 1 in CH2Cl2 by [FeIII(η5-C5H5)2](PF6) and AgBF4, respectively. A structural analysis of the single crystals of the monocation and the dication with the compositions [1OX1](PF6)·CH2Cl2·H2O (2) and [1OX2](BF4)2·1.7H2O (3), respectively, has been done. Metrical (metal–ligand and ligand backbone) parameters, values of metrical oxidation states of coordinated ligands, 1H NMR spectra of 1 and [1OX2](BF4)2·H2O, EPR spectra of [1OX1](PF6)·CH2Cl2, X-ray photoelectron and UV-VIS-NIR spectra of 1–3, spin population analysis from broken-symmetry (BS) density functional theory (DFT) calculations and quasi-restricted orbital (QRO) analysis have allowed us to assign the electronic structure of the complexes. The complexes exhibit highly covalent metal–ligand interactions. The electronic states of 1, [1OX1]1+ and [1OX2]2+ are best described as [RuII{(LISQ)˙−}2] ↔ [RuIII{(LAP)2−}{(LISQ)˙−}] (S = 0), [RuIII{(LISQ)˙−}2]1+ (S = 1/2) and [RuII{(LIBQ)0}2]2+ ↔ [RuIII{(LISQ)˙−}{(LIBQ)0}]2+ (S = 0), respectively. Notably, all redox processes are ligand-centred. Absorption spectral properties have been rationalized based on time-dependent (TD)-DFT calculations. For 1, the appearance of an IVCT band at 1100 nm supports its Class II–III (borderline) ligand-based mixed-valence character.
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probing the electronic structure of ru l1 2 z z 0 1 and 2 h2l1 a tridentate 2 Aminophenol Derivative complexes in three ligand redox levels
Dalton Transactions, 2020Co-Authors: Anannya Saha, Amit Rajput, Puneet Gupta, Rabindra Nath MukherjeeAbstract:Aerobic reaction between [RuII(DMSO)4Cl2], a redox-active 2-Aminophenol-based ligand (H2L1: 2-[2-(benzylthio)phenylamino]-4,6-di-tert-butylphenol) and Et3N in MeOH under refluxing conditions afforded a purple complex [Ru(L1)2] (S = 0). Structural analysis reveals that the tridentate ligand coordinates in a mer conformation providing a distorted octahedral RuN2O2S2 coordination. Cyclic voltammetry on 1 in CH2Cl2 reveals the accessability of the monocation, dication and monoanion forms. Reddish purple monocation [Ru(L1)2](PF6)·CH2Cl2 ([1OX1](PF6)·CH2Cl2; S = 1/2) and green dication [Ru(L1)2](BF4)2·H2O ([1OX2](BF4)2·H2O; S = 0) have been isolated through the chemical oxidation of 1 in CH2Cl2 by [FeIII(η5-C5H5)2](PF6) and AgBF4, respectively. A structural analysis of the single crystals of the monocation and the dication with the compositions [1OX1](PF6)·CH2Cl2·H2O (2) and [1OX2](BF4)2·1.7H2O (3), respectively, has been done. Metrical (metal–ligand and ligand backbone) parameters, values of metrical oxidation states of coordinated ligands, 1H NMR spectra of 1 and [1OX2](BF4)2·H2O, EPR spectra of [1OX1](PF6)·CH2Cl2, X-ray photoelectron and UV-VIS-NIR spectra of 1–3, spin population analysis from broken-symmetry (BS) density functional theory (DFT) calculations and quasi-restricted orbital (QRO) analysis have allowed us to assign the electronic structure of the complexes. The complexes exhibit highly covalent metal–ligand interactions. The electronic states of 1, [1OX1]1+ and [1OX2]2+ are best described as [RuII{(LISQ)˙−}2] ↔ [RuIII{(LAP)2−}{(LISQ)˙−}] (S = 0), [RuIII{(LISQ)˙−}2]1+ (S = 1/2) and [RuII{(LIBQ)0}2]2+ ↔ [RuIII{(LISQ)˙−}{(LIBQ)0}]2+ (S = 0), respectively. Notably, all redox processes are ligand-centred. Absorption spectral properties have been rationalized based on time-dependent (TD)-DFT calculations. For 1, the appearance of an IVCT band at 1100 nm supports its Class II–III (borderline) ligand-based mixed-valence character.
Sachinath Bera - One of the best experts on this subject based on the ideXlab platform.
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cobalt ion promoted redox cascade a route to spiro oxazine oxazepine Derivatives and a dinuclear cobalt iii complex of an n 1 4 naphthoquinone o Aminophenol Derivative
Inorganic Chemistry, 2017Co-Authors: Sandip Mondal, Sachinath Bera, Suvendu Maity, Prasanta GhoshAbstract:The study discloses that the redox activity of N-(1,4-naphthoquinone)-o-Aminophenol Derivatives (LRH2) containing a (phenol)-NH-(1,4-naphthoquinone) fragment is notably different from that of a (phenol)-NH-(phenol) precursor. The former is a platform for a redox cascade. LRH2 is redox noninnocent and exists in Cat-N-(1,4-naphthoquinone)(2−) (LR 2–) and SQ-N-(1,4-naphthoquinone) (LR •–) states in the complexes. Reactions of LRH2 with cobalt(II) salts in MeOH in air promote a cascade affording spiro oxazine-oxazepine Derivatives (OXLR) in good yields, when R = H, Me, tBu. Spiro oxazine-oxazepine Derivatives are bioactive, and such a molecule has so far not been isolated by a schematic route. In this context this cascade is significant. Dimerization of LRH2 → OXLR in MeOH is a (6H+ + 6e) oxidation reaction and is composed of formations of four covalent bonds and 6-exo-trig and 7-endo-trig cyclization based on C–O coupling reactions, where MeOH is the source of a proton and the ester function. It was establis...
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Cobalt Ion Promoted Redox Cascade: A Route to Spiro Oxazine-Oxazepine Derivatives and a Dinuclear Cobalt(III) Complex of an N‑(1,4-Naphthoquinone)‑o‑Aminophenol Derivative
2017Co-Authors: Sandip Mondal, Sachinath Bera, Suvendu Maity, Prasanta GhoshAbstract:The study discloses that the redox activity of N-(1,4-naphthoquinone)-o-Aminophenol Derivatives (LRH2) containing a (phenol)-NH-(1,4-naphthoquinone) fragment is notably different from that of a (phenol)-NH-(phenol) precursor. The former is a platform for a redox cascade. LRH2 is redox noninnocent and exists in Cat-N-(1,4-naphthoquinone)(2−) (LR 2–) and SQ-N-(1,4-naphthoquinone) (LR •–) states in the complexes. Reactions of LRH2 with cobalt(II) salts in MeOH in air promote a cascade affording spiro oxazine-oxazepine Derivatives (OXLR) in good yields, when R = H, Me, tBu. Spiro oxazine-oxazepine Derivatives are bioactive, and such a molecule has so far not been isolated by a schematic route. In this context this cascade is significant. Dimerization of LRH2 → OXLR in MeOH is a (6H+ + 6e) oxidation reaction and is composed of formations of four covalent bonds and 6-exo-trig and 7-endo-trig cyclization based on C–O coupling reactions, where MeOH is the source of a proton and the ester function. It was established that the active cascade precursor is [(LMe •–)CoIIICl2] (A). Notably, formation of a spiro Derivative was not detected in CH3CN and the reaction ends up furnishing A. The route of the reaction is tunable by R, when R = NO2, it is a (2e + 4H+) oxidation reaction affording a dinuclear LR 2– complex of cobalt(III) of the type [(LNO2 2–)2CoIII2(OMe)2(H2O)2] (1) in good yields. No cascade occurs with zinc(II) ion even in MeOH and produces a LMe •– complex of type [(LMe •–)ZnIICl2] (2). The intermediate A and 2 exhibit strong EPR signals at g = 2.008 and 1.999, confrming the existence of LMe •– coordinated to low-spin cobalt(III) and zinc(II) ions. The intermediates of LRH2 → OXLR conversion were analyzed by ESI mass spectrometry. The molecular geometries of OXLR and 1 were confirmed by X-ray crystallography, and the spectral features were elucidated by TD DFT calculations