Roles of the Distinct Electronic Structures of the {Fe(NO)₂}⁹ and {Fe(NO)₂}¹⁰ Dinitrosyliron Complexes in Modulating Nitrite Binding Modes and Nitrite Activation Pathways

Nitrosylation of [PPN]2[(ONO)2Fe(η2-ONO)2] [1; PPN = bis(triphenylphosphoranylidene)ammonium] yields the nitrite-containing {Fe(NO)}7 mononitrosyliron complex (MNIC) [PPN]2[(NO)Fe(ONO)3(η2-ONO)] (2). At 4 K, complex 2 exhibits an S = 3/2 axial EPR spectrum with principal g values of g⊥ = 3.971 and g∥ = 2.000, suggestive of the {FeIII(NO−)}7 electronic structure. Addition of 1 equiv of PPh3 to complex 2 triggers O-atom transfer of the chelating nitrito ligand under mild conditions to yield the {Fe(NO)2}9 dinitrosyliron complex (DNIC) [PPN][(ONO)2Fe(NO)2] (3). These results demonstrate that both electronic structure [{FeIII(NO−)}7, S = 3/2] and redox-active ligands ([RS]− for [(RS)3Fe(NO)]− and [NO−] for complex 2) are required for the transformation of {Fe(NO)}7 MNICs into {Fe(NO)2}9 DNICs. In comparison with the PPh3-triggered O-atom abstraction of the chelating nitrito ligand of the {Fe(NO)2}9 DNIC [(1-MeIm)2(η2-ONO)Fe(NO)2] (5; 1-MeIm = 1-methylimidazole) to generate the {Fe(NO)2}10 DNIC [(1-MeIm)(PPh3)Fe(NO)2] (6), glacial acetic acid protonation of the N-bound nitro ligand in the {Fe(NO)2}10 DNIC [PPN][(η1-NO2)(PPh3)Fe(NO)2] (7) produced the {Fe(NO)2}9 DNIC [PPN][(OAc)2Fe(NO)2] (8), nitric oxide, and H2O. These results demonstrate that the distinct electronic structures of {Fe(NO)2}9/10 motifs [{Fe(NO)2}9 vs {Fe(NO)2}10] play crucial roles in modulating nitrite binding modes (O-bound chelating/monodentate nitrito for {Fe(NO)2}9 DNICs vs N-bound nitro as a π acceptor for {Fe(NO)2}10 DNICs) and regulating nitrite activation pathways (O-atom abstraction by PPh3 leading to the intermediate with a nitroxyl-coordinated ligand vs protonation accompanied by dehydration leading to the intermediate with a nitrosonium-coordinated ligand). That is, the redox shuttling between the {Fe(NO)2}9 and {Fe(NO)2}10 DNICs modulates the nitrite binding modes and then triggers nitrite activation to generate nitric oxide

Roles of the Distinct Electronic Structures of the {Fe(NO)₂}⁹ and {Fe(NO)₂}¹⁰ Dinitrosyliron Complexes in Modulating Nitrite Binding Modes and Nitrite Activation Pathways

Nitrosylation of [PPN]2[(ONO)2Fe(η2-ONO)2] [1; PPN = bis(triphenylphosphoranylidene)ammonium] yields the nitrite-containing {Fe(NO)}7 mononitrosyliron complex (MNIC) [PPN]2[(NO)Fe(ONO)3(η2-ONO)] (2). At 4 K, complex 2 exhibits an S = 3/2 axial EPR spectrum with principal g values of g⊥ = 3.971 and g∥ = 2.000, suggestive of the {FeIII(NO−)}7 electronic structure. Addition of 1 equiv of PPh3 to complex 2 triggers O-atom transfer of the chelating nitrito ligand under mild conditions to yield the {Fe(NO)2}9 dinitrosyliron complex (DNIC) [PPN][(ONO)2Fe(NO)2] (3). These results demonstrate that both electronic structure [{FeIII(NO−)}7, S = 3/2] and redox-active ligands ([RS]− for [(RS)3Fe(NO)]− and [NO−] for complex 2) are required for the transformation of {Fe(NO)}7 MNICs into {Fe(NO)2}9 DNICs. In comparison with the PPh3-triggered O-atom abstraction of the chelating nitrito ligand of the {Fe(NO)2}9 DNIC [(1-MeIm)2(η2-ONO)Fe(NO)2] (5; 1-MeIm = 1-methylimidazole) to generate the {Fe(NO)2}10 DNIC [(1-MeIm)(PPh3)Fe(NO)2] (6), glacial acetic acid protonation of the N-bound nitro ligand in the {Fe(NO)2}10 DNIC [PPN][(η1-NO2)(PPh3)Fe(NO)2] (7) produced the {Fe(NO)2}9 DNIC [PPN][(OAc)2Fe(NO)2] (8), nitric oxide, and H2O. These results demonstrate that the distinct electronic structures of {Fe(NO)2}9/10 motifs [{Fe(NO)2}9 vs {Fe(NO)2}10] play crucial roles in modulating nitrite binding modes (O-bound chelating/monodentate nitrito for {Fe(NO)2}9 DNICs vs N-bound nitro as a π acceptor for {Fe(NO)2}10 DNICs) and regulating nitrite activation pathways (O-atom abstraction by PPh3 leading to the intermediate with a nitroxyl-coordinated ligand vs protonation accompanied by dehydration leading to the intermediate with a nitrosonium-coordinated ligand). That is, the redox shuttling between the {Fe(NO)2}9 and {Fe(NO)2}10 DNICs modulates the nitrite binding modes and then triggers nitrite activation to generate nitric oxide

Roles of the Distinct Electronic Structures of the {Fe(NO)₂}⁹ and {Fe(NO)₂}¹⁰ Dinitrosyliron Complexes in Modulating Nitrite Binding Modes and Nitrite Activation Pathways

Nitrosylation of [PPN]2[(ONO)2Fe(η2-ONO)2] [1; PPN = bis(triphenylphosphoranylidene)ammonium] yields the nitrite-containing {Fe(NO)}7 mononitrosyliron complex (MNIC) [PPN]2[(NO)Fe(ONO)3(η2-ONO)] (2). At 4 K, complex 2 exhibits an S = 3/2 axial EPR spectrum with principal g values of g⊥ = 3.971 and g∥ = 2.000, suggestive of the {FeIII(NO−)}7 electronic structure. Addition of 1 equiv of PPh3 to complex 2 triggers O-atom transfer of the chelating nitrito ligand under mild conditions to yield the {Fe(NO)2}9 dinitrosyliron complex (DNIC) [PPN][(ONO)2Fe(NO)2] (3). These results demonstrate that both electronic structure [{FeIII(NO−)}7, S = 3/2] and redox-active ligands ([RS]− for [(RS)3Fe(NO)]− and [NO−] for complex 2) are required for the transformation of {Fe(NO)}7 MNICs into {Fe(NO)2}9 DNICs. In comparison with the PPh3-triggered O-atom abstraction of the chelating nitrito ligand of the {Fe(NO)2}9 DNIC [(1-MeIm)2(η2-ONO)Fe(NO)2] (5; 1-MeIm = 1-methylimidazole) to generate the {Fe(NO)2}10 DNIC [(1-MeIm)(PPh3)Fe(NO)2] (6), glacial acetic acid protonation of the N-bound nitro ligand in the {Fe(NO)2}10 DNIC [PPN][(η1-NO2)(PPh3)Fe(NO)2] (7) produced the {Fe(NO)2}9 DNIC [PPN][(OAc)2Fe(NO)2] (8), nitric oxide, and H2O. These results demonstrate that the distinct electronic structures of {Fe(NO)2}9/10 motifs [{Fe(NO)2}9 vs {Fe(NO)2}10] play crucial roles in modulating nitrite binding modes (O-bound chelating/monodentate nitrito for {Fe(NO)2}9 DNICs vs N-bound nitro as a π acceptor for {Fe(NO)2}10 DNICs) and regulating nitrite activation pathways (O-atom abstraction by PPh3 leading to the intermediate with a nitroxyl-coordinated ligand vs protonation accompanied by dehydration leading to the intermediate with a nitrosonium-coordinated ligand). That is, the redox shuttling between the {Fe(NO)2}9 and {Fe(NO)2}10 DNICs modulates the nitrite binding modes and then triggers nitrite activation to generate nitric oxide

Roles of the Distinct Electronic Structures of the {Fe(NO)₂}⁹ and {Fe(NO)₂}¹⁰ Dinitrosyliron Complexes in Modulating Nitrite Binding Modes and Nitrite Activation Pathways

Nitrosylation of [PPN]2[(ONO)2Fe(η2-ONO)2] [1; PPN = bis(triphenylphosphoranylidene)ammonium] yields the nitrite-containing {Fe(NO)}7 mononitrosyliron complex (MNIC) [PPN]2[(NO)Fe(ONO)3(η2-ONO)] (2). At 4 K, complex 2 exhibits an S = 3/2 axial EPR spectrum with principal g values of g⊥ = 3.971 and g∥ = 2.000, suggestive of the {FeIII(NO−)}7 electronic structure. Addition of 1 equiv of PPh3 to complex 2 triggers O-atom transfer of the chelating nitrito ligand under mild conditions to yield the {Fe(NO)2}9 dinitrosyliron complex (DNIC) [PPN][(ONO)2Fe(NO)2] (3). These results demonstrate that both electronic structure [{FeIII(NO−)}7, S = 3/2] and redox-active ligands ([RS]− for [(RS)3Fe(NO)]− and [NO−] for complex 2) are required for the transformation of {Fe(NO)}7 MNICs into {Fe(NO)2}9 DNICs. In comparison with the PPh3-triggered O-atom abstraction of the chelating nitrito ligand of the {Fe(NO)2}9 DNIC [(1-MeIm)2(η2-ONO)Fe(NO)2] (5; 1-MeIm = 1-methylimidazole) to generate the {Fe(NO)2}10 DNIC [(1-MeIm)(PPh3)Fe(NO)2] (6), glacial acetic acid protonation of the N-bound nitro ligand in the {Fe(NO)2}10 DNIC [PPN][(η1-NO2)(PPh3)Fe(NO)2] (7) produced the {Fe(NO)2}9 DNIC [PPN][(OAc)2Fe(NO)2] (8), nitric oxide, and H2O. These results demonstrate that the distinct electronic structures of {Fe(NO)2}9/10 motifs [{Fe(NO)2}9 vs {Fe(NO)2}10] play crucial roles in modulating nitrite binding modes (O-bound chelating/monodentate nitrito for {Fe(NO)2}9 DNICs vs N-bound nitro as a π acceptor for {Fe(NO)2}10 DNICs) and regulating nitrite activation pathways (O-atom abstraction by PPh3 leading to the intermediate with a nitroxyl-coordinated ligand vs protonation accompanied by dehydration leading to the intermediate with a nitrosonium-coordinated ligand). That is, the redox shuttling between the {Fe(NO)2}9 and {Fe(NO)2}10 DNICs modulates the nitrite binding modes and then triggers nitrite activation to generate nitric oxide

Roles of the Distinct Electronic Structures of the {Fe(NO)₂}⁹ and {Fe(NO)₂}¹⁰ Dinitrosyliron Complexes in Modulating Nitrite Binding Modes and Nitrite Activation Pathways

Nitrosylation of [PPN]2[(ONO)2Fe(η2-ONO)2] [1; PPN = bis(triphenylphosphoranylidene)ammonium] yields the nitrite-containing {Fe(NO)}7 mononitrosyliron complex (MNIC) [PPN]2[(NO)Fe(ONO)3(η2-ONO)] (2). At 4 K, complex 2 exhibits an S = 3/2 axial EPR spectrum with principal g values of g⊥ = 3.971 and g∥ = 2.000, suggestive of the {FeIII(NO−)}7 electronic structure. Addition of 1 equiv of PPh3 to complex 2 triggers O-atom transfer of the chelating nitrito ligand under mild conditions to yield the {Fe(NO)2}9 dinitrosyliron complex (DNIC) [PPN][(ONO)2Fe(NO)2] (3). These results demonstrate that both electronic structure [{FeIII(NO−)}7, S = 3/2] and redox-active ligands ([RS]− for [(RS)3Fe(NO)]− and [NO−] for complex 2) are required for the transformation of {Fe(NO)}7 MNICs into {Fe(NO)2}9 DNICs. In comparison with the PPh3-triggered O-atom abstraction of the chelating nitrito ligand of the {Fe(NO)2}9 DNIC [(1-MeIm)2(η2-ONO)Fe(NO)2] (5; 1-MeIm = 1-methylimidazole) to generate the {Fe(NO)2}10 DNIC [(1-MeIm)(PPh3)Fe(NO)2] (6), glacial acetic acid protonation of the N-bound nitro ligand in the {Fe(NO)2}10 DNIC [PPN][(η1-NO2)(PPh3)Fe(NO)2] (7) produced the {Fe(NO)2}9 DNIC [PPN][(OAc)2Fe(NO)2] (8), nitric oxide, and H2O. These results demonstrate that the distinct electronic structures of {Fe(NO)2}9/10 motifs [{Fe(NO)2}9 vs {Fe(NO)2}10] play crucial roles in modulating nitrite binding modes (O-bound chelating/monodentate nitrito for {Fe(NO)2}9 DNICs vs N-bound nitro as a π acceptor for {Fe(NO)2}10 DNICs) and regulating nitrite activation pathways (O-atom abstraction by PPh3 leading to the intermediate with a nitroxyl-coordinated ligand vs protonation accompanied by dehydration leading to the intermediate with a nitrosonium-coordinated ligand). That is, the redox shuttling between the {Fe(NO)2}9 and {Fe(NO)2}10 DNICs modulates the nitrite binding modes and then triggers nitrite activation to generate nitric oxide

UF₃(H₂O)(C₂O₄)_0.5: A Fluorooxalate of Tetravalent Uranium with a Three-Dimensional Framework Structure

A new uranium(IV) fluorooxalate, UF3(H2O)(C2O4)0.5, has been synthesized by a hydrothermal method and structurally characterized by single-crystal X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. The structure consists of two-dimensional layers of corner- and edge-sharing tricapped trigonal prisms with the composition UF4/2F2/2O3 linked by bisbidentate oxalate ligands to form a three-dimensional framework. Magnetic susceptibilities were measured to confirm the tetravalent state of uranium. Crystal data:  monoclinic, space group C2/c, a = 17.246(3) Å, b = 6.088(1) Å, c = 8.589(2) Å, β = 95.43(3)°, and Z = 8

UF₃(H₂O)(C₂O₄)_0.5: A Fluorooxalate of Tetravalent Uranium with a Three-Dimensional Framework Structure

A new uranium(IV) fluorooxalate, UF3(H2O)(C2O4)0.5, has been synthesized by a hydrothermal method and structurally characterized by single-crystal X-ray diffraction, infrared spectroscopy, and thermogravimetric analysis. The structure consists of two-dimensional layers of corner- and edge-sharing tricapped trigonal prisms with the composition UF4/2F2/2O3 linked by bisbidentate oxalate ligands to form a three-dimensional framework. Magnetic susceptibilities were measured to confirm the tetravalent state of uranium. Crystal data:  monoclinic, space group C2/c, a = 17.246(3) Å, b = 6.088(1) Å, c = 8.589(2) Å, β = 95.43(3)°, and Z = 8

Enantioselective Synthesis of Nabscessin C

Enantioselective synthesis of nabscessin C (1), an aminocyclitol amide with antimicrobial activity, is reported. Starting from myo-inositol, (+)-nabscessin C was synthesized in 12 isolation steps. Desymmetrization of 2-deoxygenated 4,6-dibenzylinositol was achieved using lipase from porcine pancreas (PPL), and the stereochemistry was established by X-ray crystallography. This method has the potential for synthesizing other cyclitol-derived compounds

Ca₂[Ti(HPO₄)₂(PO₄)]·H₂O, Ca[Ti₂(H₂O)(HPO₃)₄]·H₂O, and Ti(H₂PO₂)₃: Solid-State Oxidation via Proton-Coupled Electron Transfer

Titanium phosphorus oxides (TiPOs) are promising energy-conversion materials, but most are of tetravalent titanium (TiIV), with the trivalent TiIIIPOs less explored because of instability and obstacles in synthesis. In this study, we used a simple synthetic strategy and prepared three new TiIIIPOs with different phosphorus oxoanions: the phosphate Ca2Ti­(HPO4)2(PO4)·H2O (1), the phosphite CaTi2(H2O)­(HPO3)4·H2O (2), and the hypophosphite Ti­(H2PO2)3 (3). Each possesses different structures in one, two, and three dimensions, yet they are related to one another because of their infinite chains. Compound 1 exhibits proton-coupled electron transfer (PCET) reactivity in a solid state, losing one proton from its own HPO4 in oxidation to yield Ca2Ti­(HPO4)­(PO4)2·H2O (designated as 1O), while compound 2 also exhibits PCET reactivity in which the octahedral core [TiIII(H2O)]3+ gives off two protons to become a titanyl unit [TiIVO]2+ under oxidation, yielding CaTi2O­(HPO3)4·H2O (2O). Both 1O and 2O retain their original frameworks from before oxidation, but there are some changes in the hydrogen and Ti–O bonds that affect the IR absorption and powder X-ray diffraction patterns. Compound 3 represents the first titanium hypophosphite, and two polymorphs were discovered that show structures related to 1 and 2. This work demonstrates a simple strategy that is effective for preparing titanium­(III) compounds in a pure phase; further, new findings in the pathways of solid-state PCET reactions promote a greater understanding of the self-sustaining oxidation behavior for TiIIIPO solid materials

Photoinduced Mechanical Motions of Biferrocene-Containing Pseudorotaxane Crystals

This study presents photoresponsive, dynamic pseudorotaxane crystals composed of axle molecules containing biferrocene or ferrocene groups threaded through a dibenzo[24]­crown-8 ether ring. A biferrocene-containing pseudorotaxane crystal is used for photomechanical conversion under 445 nm laser irradiation and provides a lifting force that is 2900 times the weight of the crystal itself