NHC Metal (Silver, Mercury, and Nickel) Complexes Based on Quinoxaline–Dibenzimidazolium Salts: Synthesis, Structural Studies, and Fluorescent Chemosensors for Cu²⁺ by Charge Transfer

The two dibenzimidazolium salts 2,3-bis­[(1-ⁿPr-benzimidazoliumyl)­methyl]­quinoxaline hexafluorophosphate (<b>H</b>_<b>2</b><b>-1a</b>) and 2,3-bis­[(1-Pi-benzimidazoliumyl)­methyl]­quinoxaline hexafluorophosphate (<b>H</b>_<b>2</b><b>-1b</b>) (ⁿPr = <i>n</i>-propyl and Pi = picolyl) and their four NHC metal complexes [Ag₂(<b>1a</b>)₂]­(PF₆)₂ (<b>2a</b>), [Hg­(<b>1a</b>)­(OAc)­(H₂O)]₂(PF₆)₂ (<b>2b</b>), [Ag₂(<b>1b</b>)₂]­(PF₆)₂ (<b>2c</b>) and [Ni­(<b>1b</b>)]­(NiCl₄) (<b>2d</b>) have been synthesized and characterized. Each cation in <b>2a</b>,<b>c</b> possesses a boxlike structure with different sizes. In <b>2b</b>, one 18-membered macrometallacycle is formed by two bidentate NHC ligands and two mercury­(II) atoms, in which an inversion center is observed. In <b>2d</b>, one nickel­(II) atom is surrounded by two carbene carbon atoms and two nitrogen atoms from two pyridine rings to adopt a square geometry. The recognition of Cu²⁺ using <b>2a</b>,<b>c</b> as chemosensors by charge transfer was investigated on the basis of fluorescence and UV/vis spectroscopic titrations. The results show that complexes <b>2a</b>,<b>c</b> are effective chemosensors for Cu²⁺

NHC Metal (Silver, Mercury, and Nickel) Complexes Based on Quinoxaline–Dibenzimidazolium Salts: Synthesis, Structural Studies, and Fluorescent Chemosensors for Cu²⁺ by Charge Transfer

The two dibenzimidazolium salts 2,3-bis­[(1-ⁿPr-benzimidazoliumyl)­methyl]­quinoxaline hexafluorophosphate (<b>H</b>_<b>2</b><b>-1a</b>) and 2,3-bis­[(1-Pi-benzimidazoliumyl)­methyl]­quinoxaline hexafluorophosphate (<b>H</b>_<b>2</b><b>-1b</b>) (ⁿPr = <i>n</i>-propyl and Pi = picolyl) and their four NHC metal complexes [Ag₂(<b>1a</b>)₂]­(PF₆)₂ (<b>2a</b>), [Hg­(<b>1a</b>)­(OAc)­(H₂O)]₂(PF₆)₂ (<b>2b</b>), [Ag₂(<b>1b</b>)₂]­(PF₆)₂ (<b>2c</b>) and [Ni­(<b>1b</b>)]­(NiCl₄) (<b>2d</b>) have been synthesized and characterized. Each cation in <b>2a</b>,<b>c</b> possesses a boxlike structure with different sizes. In <b>2b</b>, one 18-membered macrometallacycle is formed by two bidentate NHC ligands and two mercury­(II) atoms, in which an inversion center is observed. In <b>2d</b>, one nickel­(II) atom is surrounded by two carbene carbon atoms and two nitrogen atoms from two pyridine rings to adopt a square geometry. The recognition of Cu²⁺ using <b>2a</b>,<b>c</b> as chemosensors by charge transfer was investigated on the basis of fluorescence and UV/vis spectroscopic titrations. The results show that complexes <b>2a</b>,<b>c</b> are effective chemosensors for Cu²⁺

A mesitylene-bridged bis-benzimidazolyl ligand and six metal coordination compounds

<p>The mesitylene-bridged bis-benzimidazolyl ligand 1,3-bis(benzimidazol-1′-yl-methyl)mesitylene (<b>L</b>) and six metal complexes, [Cu₉L₆(OH)₇Cl₈] (<b>1</b>), [Co₂L₄(NO₃)(H₂O)₂](NO₃)₃ (<b>2</b>), [Zn₂L₂Cl₄] (<b>3</b>), [CdL₂(NO₃)₂]_n (<b>4</b>), [MnL(L_A)(CH₃OH)]_n (<b>5</b>), and [CoLCl₂]_n (<b>6</b>) (L_<b>A</b> = terephthalate), have been prepared and characterized. Complex <b>1</b> is a football-like cluster formed by six <b>L</b>s, nine Cu(II) ions, eight chlorides, and seven hydroxides, in which the size of the football is about 13.9 × 15.4 Å. Complex <b>2</b> contains a cage-like ball formed by four <b>L</b>s and two Co(II) ions, in which the external and internal sizes of the ball are about 12.2 × 14.6 Å and 6.5 × 10.7 Å, respectively. In this complex, one nitrate is fixed in the middle of the cage through two Co–O bonds. The 24-membered metallomacrocycle of <b>3</b> is formed by two <b>L</b>s and two Zn(II) ions. In <b>4</b>, 2-D layers with 48-membered metallomacrocycles are formed via <b>L</b>s and Cd(II) ions. In <b>5</b>, <b>L</b> and terephthalate ions (<b>L</b>_<b>A</b>) participate in coordination with Mn(II) to afford 2-D network layers. The 1-D polymeric chain of <b>6</b> is formed via <b>L</b> and Co(II) chloride moieties. In the crystal packing of <b>1</b>–<b>6</b>, 2-D supramolecular layers and 3-D supramolecular frameworks are formed via intermolecular weak interactions, including hydrogen bonds, <i>π</i>–<i>π</i> interactions, and C–H⋯<i>π</i> contacts. The conformations of metal complexes from <b>L</b> are described. Additionally, the fluorescence emission spectra of <b>L</b> and <b>1</b>–<b>6</b> are reported.</p> <p><b>Software of Graphics:</b> Ligand <b>L</b>, <b>H2LA</b> and Schemes 1–3: Chem Draw 8.0</p> <p>Figures 1–6: Diamand 3.0</p> <p>Figure 7: Origin 8.0</p

NHC Tetranuclear Silver(I) Complexes and Intramolecular Extended π–π Interactions

A series of new acyclic tetrazolium salts featuring a central anthracence building block which were 9,10-substituted with (N-R-azoliumCH₂CH₂)₂NCH₂– groups were prepared (azolium = benzimidazolium or imidazolium, R = picolyl, ethyl, ^<i>n</i>butyl, or benzyl). These tetrazolium salts were metalated with silver­(I) leading to four novel NHC tetranuclear complexes <b>1</b>–<b>4</b>. Molecular structures of <b>1</b>–<b>4</b> and one tetraimidazolium salt <b>L</b>^<b>1</b><b>H</b>_<b>4</b><b>·(HgI</b>_<b>4</b><b>)</b>_<b>2</b> were established by ¹H NMR, ¹³C NMR spectroscopy and X-ray crystallography. Silver­(I) η³-arene interactions exist in complex <b>1</b>. Each molecule of complexes <b>2</b>–<b>4</b> contains one 42-membered and two 21-membered macrometallocycles. It was interesting to observe intramolecular extended π–π interactions originated from imidazole–anthracene–anthracene–imidazole in complexes <b>3</b> and <b>4</b>. In addition, the fluorescence emission spectra of the complexes and the tetrazolium salts were studied

Zinc(II), Cobalt(II), and Copper(II) Complexes Based on Dibenzimidazolyl Bidentate Ligands with Oligoether Linkers: Crystal Structure and Weak Interactions

The seven metal complexes, [Zn(L₁)₂]_<i>n</i> (<b>1</b>), [Co(L₂)(L_A)]_<i>n</i> (<b>2</b>), [Zn(L₂)(L_B)]_<i>n</i> (<b>3</b>), [Cu(L₂)(SO₄)]₂ (<b>4</b>), [Co₂(L₁)₂Cl₄] (<b>5</b>), [Co(L₂)(L_C)₂] (<b>6</b>), and [Zn(L₂)(NO₃)₂] (<b>7</b>) (<b>L</b>_<b>1</b> = 2,2′-bis(benzimidazol-l-yl)ethylether, <b>L</b>_<b>2</b> = 1,2-bis[2′-(benzimidazol-1-yl)ethoxy]ethane, <b>L</b>_<b>A</b> = succinate, <b>L</b>_<b>B</b> = terephthalate, and <b>L</b>_<b>C</b> = 4-aminobenzoate) have been prepared by means of self-assemblies of Zn(II), Cu(II), or Co(II) salts, dibenzimidazolyl bidentate ligands with oligoether linkers, and organic acids (succinic acid (H₂L_A) for <b>2</b>, terephthalic acid (H₂L_B) for <b>3</b>, and 4-aminobenzoic acid (HL_C) for <b>6</b>). These complexes are structurally characterized by X-ray diffraction analyses. In complexes <b>1</b>–<b>3</b>, one-dimensional (1D) polymeric chains are formed via metal centers and ligands. In complex <b>4</b>, two 15-membered metallomacrocycles are connected by two sulfate groups to form a dimer. Complex <b>5</b> contains a 24-membered metallomacrocycle formed by two ligands and two Co(II) atoms. Each of complexes <b>6</b> and <b>7</b> contains a 15-membered metallomacrocycle formed by one ligand and one metal atom. In the crystal packings of complexes <b>1</b>–<b>7</b>, two-dimensional (2D) supramolecular layers and three-dimensional (3D) supramolecular frameworks are formed via intermolecular weak interactions, including π–π interactions, hydrogen bonds, and C–H···π contacts. Additionally, the fluorescence emission spectra and quantum yields of ligands and metal complexes are described

NHC Pd(II) and Ag(I) Complexes: Synthesis, Structure, and Catalytic Activity in Three Types of C–C Coupling Reactions

Four bis-benzimidazolium salts, 1,4-bis­[1′-(<i>N</i>-R-benzimidazoliumyl)­methyl]-2,3,5,6-tetramethylbenzene 2X^– (<b>L</b>^<b>1</b><b>H</b>_<b>2</b><b>·(PF</b>_<b>6</b><b>)</b>_<b>2</b>: R = ethyl, X = PF₆; <b>L</b>^<b>2</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = picolyl, X = Br; <b>L</b>^<b>3</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = benzyl, X = Br; and <b>L</b>^<b>4</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = allyl, X = Br), and their three <i>N</i>-heterocyclic carbene (NHC) Pd­(II) and Ag­(I) complexes, <b>L</b>^<b>1</b><b>Pd</b>_<b>2</b><b>Cl</b>_<b>4</b> (<b>1</b>), <b>L</b>^<b>2</b><b>Ag</b>_<b>2</b><b>Br</b>_<b>2</b> (<b>2</b>), and <b>L</b>^<b>4</b><b>(AgBr)</b>_<b>2</b> (<b>3</b>), as well as one anionic complex <b>L</b>^<b>3</b><b>H</b>_<b>2</b><b>·(Ag</b>_<b>4</b><b>Br</b>_<b>8</b><b>)</b>_<b>0.5</b> (<b>4</b>), have been synthesized and characterized. Complex <b>1</b> adopts a funnel-like type of structure, complex <b>2</b> adopts a cyclic structure, and complex <b>3</b> is an open structure. In the crystal packing of <b>1</b>–<b>4</b>, one-dimensional polymeric chains and two-dimensional supramolecular layers are formed via intermolecular weak interactions, including hydrogen bonds, π–π interactions, and C–H···π contacts. The catalytic activities of NHC Pd­(II) complex <b>1</b> in three types of C–C coupling reactions (Suzuki–Miyaura, Heck–Mizoroki, and Sonogashira reactions) were studied. The results show that this catalytic system is efficient for these C–C coupling reactions

NHC Pd(II) and Ag(I) Complexes: Synthesis, Structure, and Catalytic Activity in Three Types of C–C Coupling Reactions

Four bis-benzimidazolium salts, 1,4-bis­[1′-(<i>N</i>-R-benzimidazoliumyl)­methyl]-2,3,5,6-tetramethylbenzene 2X^– (<b>L</b>^<b>1</b><b>H</b>_<b>2</b><b>·(PF</b>_<b>6</b><b>)</b>_<b>2</b>: R = ethyl, X = PF₆; <b>L</b>^<b>2</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = picolyl, X = Br; <b>L</b>^<b>3</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = benzyl, X = Br; and <b>L</b>^<b>4</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = allyl, X = Br), and their three <i>N</i>-heterocyclic carbene (NHC) Pd­(II) and Ag­(I) complexes, <b>L</b>^<b>1</b><b>Pd</b>_<b>2</b><b>Cl</b>_<b>4</b> (<b>1</b>), <b>L</b>^<b>2</b><b>Ag</b>_<b>2</b><b>Br</b>_<b>2</b> (<b>2</b>), and <b>L</b>^<b>4</b><b>(AgBr)</b>_<b>2</b> (<b>3</b>), as well as one anionic complex <b>L</b>^<b>3</b><b>H</b>_<b>2</b><b>·(Ag</b>_<b>4</b><b>Br</b>_<b>8</b><b>)</b>_<b>0.5</b> (<b>4</b>), have been synthesized and characterized. Complex <b>1</b> adopts a funnel-like type of structure, complex <b>2</b> adopts a cyclic structure, and complex <b>3</b> is an open structure. In the crystal packing of <b>1</b>–<b>4</b>, one-dimensional polymeric chains and two-dimensional supramolecular layers are formed via intermolecular weak interactions, including hydrogen bonds, π–π interactions, and C–H···π contacts. The catalytic activities of NHC Pd­(II) complex <b>1</b> in three types of C–C coupling reactions (Suzuki–Miyaura, Heck–Mizoroki, and Sonogashira reactions) were studied. The results show that this catalytic system is efficient for these C–C coupling reactions

NHC Pd(II) and Ag(I) Complexes: Synthesis, Structure, and Catalytic Activity in Three Types of C–C Coupling Reactions

Four bis-benzimidazolium salts, 1,4-bis­[1′-(<i>N</i>-R-benzimidazoliumyl)­methyl]-2,3,5,6-tetramethylbenzene 2X^– (<b>L</b>^<b>1</b><b>H</b>_<b>2</b><b>·(PF</b>_<b>6</b><b>)</b>_<b>2</b>: R = ethyl, X = PF₆; <b>L</b>^<b>2</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = picolyl, X = Br; <b>L</b>^<b>3</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = benzyl, X = Br; and <b>L</b>^<b>4</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = allyl, X = Br), and their three <i>N</i>-heterocyclic carbene (NHC) Pd­(II) and Ag­(I) complexes, <b>L</b>^<b>1</b><b>Pd</b>_<b>2</b><b>Cl</b>_<b>4</b> (<b>1</b>), <b>L</b>^<b>2</b><b>Ag</b>_<b>2</b><b>Br</b>_<b>2</b> (<b>2</b>), and <b>L</b>^<b>4</b><b>(AgBr)</b>_<b>2</b> (<b>3</b>), as well as one anionic complex <b>L</b>^<b>3</b><b>H</b>_<b>2</b><b>·(Ag</b>_<b>4</b><b>Br</b>_<b>8</b><b>)</b>_<b>0.5</b> (<b>4</b>), have been synthesized and characterized. Complex <b>1</b> adopts a funnel-like type of structure, complex <b>2</b> adopts a cyclic structure, and complex <b>3</b> is an open structure. In the crystal packing of <b>1</b>–<b>4</b>, one-dimensional polymeric chains and two-dimensional supramolecular layers are formed via intermolecular weak interactions, including hydrogen bonds, π–π interactions, and C–H···π contacts. The catalytic activities of NHC Pd­(II) complex <b>1</b> in three types of C–C coupling reactions (Suzuki–Miyaura, Heck–Mizoroki, and Sonogashira reactions) were studied. The results show that this catalytic system is efficient for these C–C coupling reactions

NHC Pd(II) and Ag(I) Complexes: Synthesis, Structure, and Catalytic Activity in Three Types of C–C Coupling Reactions

Four bis-benzimidazolium salts, 1,4-bis­[1′-(<i>N</i>-R-benzimidazoliumyl)­methyl]-2,3,5,6-tetramethylbenzene 2X^– (<b>L</b>^<b>1</b><b>H</b>_<b>2</b><b>·(PF</b>_<b>6</b><b>)</b>_<b>2</b>: R = ethyl, X = PF₆; <b>L</b>^<b>2</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = picolyl, X = Br; <b>L</b>^<b>3</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = benzyl, X = Br; and <b>L</b>^<b>4</b><b>H</b>_<b>2</b><b>·Br</b>_<b>2</b>: R = allyl, X = Br), and their three <i>N</i>-heterocyclic carbene (NHC) Pd­(II) and Ag­(I) complexes, <b>L</b>^<b>1</b><b>Pd</b>_<b>2</b><b>Cl</b>_<b>4</b> (<b>1</b>), <b>L</b>^<b>2</b><b>Ag</b>_<b>2</b><b>Br</b>_<b>2</b> (<b>2</b>), and <b>L</b>^<b>4</b><b>(AgBr)</b>_<b>2</b> (<b>3</b>), as well as one anionic complex <b>L</b>^<b>3</b><b>H</b>_<b>2</b><b>·(Ag</b>_<b>4</b><b>Br</b>_<b>8</b><b>)</b>_<b>0.5</b> (<b>4</b>), have been synthesized and characterized. Complex <b>1</b> adopts a funnel-like type of structure, complex <b>2</b> adopts a cyclic structure, and complex <b>3</b> is an open structure. In the crystal packing of <b>1</b>–<b>4</b>, one-dimensional polymeric chains and two-dimensional supramolecular layers are formed via intermolecular weak interactions, including hydrogen bonds, π–π interactions, and C–H···π contacts. The catalytic activities of NHC Pd­(II) complex <b>1</b> in three types of C–C coupling reactions (Suzuki–Miyaura, Heck–Mizoroki, and Sonogashira reactions) were studied. The results show that this catalytic system is efficient for these C–C coupling reactions