Application of Open Chain Tetraimidazolium Salts as Precursors for the Synthesis of Silver Tetra(NHC) Complexes

Weiss, Daniel T.; Haslinger, Stefan; Jandl, Christian; Pöthig, Alexander; Cokoja, Mirza; Kühn, Fritz E.

doi:10.1021/ic502838x

Cited by 40 publications

(28 citation statements)

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“…ESI-MS data for 4 confirms the dimeric, tetranuclear structure with m/z = 1894.60. In analogy to 1, 38 variable temperature (VT) 1 H NMR spectra of coinage metal complexes 3 and 4 reveal the existence of different conformers in solution (see Figure S3 and S6 in the Supporting Information, SI). For complex 3, an elevation of the temperature from -40 °C to 0 °C results in peak broadening, while a further increase in temperature to 70 °C leads to sharp signals.…”

Section: Resultsmentioning

confidence: 99%

“…In contrast to 1, silver complex 2 exhibits a monomeric, dinuclear structure with linear coordination of the coinage metal ions due to the longer and more flexible propylene bridge of ligand L2. 38 Silver complex 2 was treated with CuCl and Au(SMe 2 )Cl to yield complexes 5 and 6, respectively (Scheme 2). As observed for 3 and 4, copper complex 5 is only stable under inert conditions while gold complex 6 is air stable.…”

Section: Resultsmentioning

confidence: 99%

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Structural diversity of late transition metal complexes with flexible tetra-NHC ligands

et al. 2015

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The synthesis of copper, gold, nickel, palladium, platinum, and iron complexes with open chain tetra-N-heterocyclic carbene (NHC) ligands via transmetalation using silver NHC complexes is presented. The obtained complexes show differing coordination geometries depending on both ligand structure and metal. While the complexes of the coinage metals form di- or tetranuclear structures, the group 10 metal complexes exhibit a distorted square planar coordination geometry at the metal centers. In the case of iron an enhanced flexibility of the ligand - caused by a longer alkyl bridge - leads to octahedral complexes with a sawhorse-type coordination by the tetracarbene ligand and two cis acetonitrile ligands. To the best of our knowledge, this is the first known example of a tetracarbene ligand in sawhorse-type coordination within an octahedral coordination sphere. The remaining cis-labile sites are prone to exchange reactions as shown by addition of trimethylphosphine.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Structural diversity of late transition metal complexes with flexible tetra-NHC ligands

et al. 2015

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“…Multidentate N-heterocyclic compounds are often employed as ligands to produce polymeric networks due to their rich coordination sites and various coordination modes [1][2][3][4][5][6]. Recently, our group synthesized 1-[(benzotriazol-1-yl)methyl]-1-H-1,3-(2-methyl-imdazol), and studied its coordination behavior with transitional metal halides (such as ZnCl 2 , CoCl 2 , CdI 2 , HgBr 2 ), obtaining a series of coordination compounds [7][8][9][10].…”

Section: Discussionmentioning

confidence: 99%

Crystal structure of aquadichloridobis(1-((2-methyl-1H-imidazol-1-yl)methyl)-1H-benotriazole-κN)mercury(II), C₂₂H₂₄Cl₂HgN₁₀O

Yang

2016

Zeitschrift Für Kristallographie - New Crystal Structures

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Source of materialA methanol solution (5 mL) of 1-((benzotriazol-1-yl)methyl)-1-H-1,3-(2-methyl-imdazol) (0.1 mmol) was added dropwise into a methanol solution (3 mL) of HgCl 2 (0.05 mmol). The resulting solution was left at room temperature. After ve days, colorless crystals were obtained and dried in air. Experimental detailsH atoms were generated geometrically, with C-H = 0.96, 0.97 and 0.93 Å for methyl, methylene and aromatic H, respectively, and constrained to ride their parent atoms with

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“…24 Acyclic tetra-NHC ligands (D) are highly flexible, and complexes are known for coinage metals, group 10 metals, and iron. 29,46 For macrocyclic ligands of type E and F a broad range of square-planar as well as linearly coordinated metal complexes is known. 10,11,17,28,30−32,47−54 In this work, the synthesis of a series of open-chain, tetradentate NHC/pyridine hybrid ligands with different NHC/pyridyl ratios and their application in the coordination of iron(II) is presented.…”

Section: ■ Introductionmentioning

confidence: 99%

“…61 Nevertheless, a combination of two recently developed strategies to access nonsymmetrically substituted diimidazolium salts was found to be successful. 29,62,63 Following the initial work of Nozaki et al, 62 who targeted asymmetrically substituted monoimidazolium salts, the group of Gardiner was able to access N,N′-asymmetrically substituted di-NHC ligands by isolating halo-methylated imidazolium salts. 63 Instead of the arylimidazole precursors used in their work, we reacted 2-imidazolylpyridine with chloroiodomethane.…”

Section: ■ Introductionmentioning

confidence: 99%

NHC Versus Pyridine: How “Teeth” Change the Redox Behavior of Iron(II) Complexes

et al. 2015

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A series of octahedral iron(II) complexes with tetradentate NHC/pyridine hybrid ligands containing up to three pyridyl units was designed to study the influence of NHC and pyridine donors on the electronic structure of the metal center. Structural analysis of the iron complexes by NMR spectroscopy and single-crystal X-ray diffraction reveals different coordination modes of the ligand depending on the linkage of the different donor moieties. The oxidation potentials of all complexes correlate linearly with the number of NHC moieties coordinated to iron, as shown by cyclic voltammetry. The influence, although minor, of structural properties on the oxidation potential and (in one case) the influence of the oxidation state of the coordination geometry of the hybrid ligand are also demonstrated. ■ INTRODUCTIONN-heterocyclic carbene (NHC) ligands have become a multifunctional tool in organometallic chemistry and homogeneous catalysis, as steric and electronic properties can be easily influenced by modification of the substituents. 1−6 During the past decade, iron NHC complexes have especially received increasing attention. 7−9 Examples of remarkable reactivity were obtained on the basis of the use of chelating, polydentate NHC ligands, 10−17 including oxidation catalysis with NHC/pyridine hybrid ligands. 18,19 Recently, it could be shown that replacing acetonitrile ligands of the catalytically active iron(II) NCCN complex has a strong influence on the electronic structure of the metal center. 20 However, the literature lacks comprehensive studies on the influence of NHC/pyridine hybrid ligands with different NHC/pyridyl ratios on the oxidation potential of the metal. Such manipulations would allow fine-tuning of the metal center without blocking labile binding sites.Several alkylene-bridged tetradentate NHC/pyridine hybrid ligands are known (Figure 1). Ligands of the general types A (NCCN) and B and C (both CNNC) as well as their arylated derivatives 21−27 count for open-chain structures, while E fits into the class of macrocyclic ligands. 28 Three types of alkylenebridged tetra-NHC ligands (CCCC) have been described so far: open-chain (D), 29 macrocyclic (F), 30−32 and mixed aryl-or heteroatom-bridged ligands. 33−38 The coordination chemistry of the aforementioned acyclic type A di-NHC ligand derivatives has been well investigated. Complexes are known for group 10 metals, 21,22,25,26,39−41 coinage metals, 22,42 cobalt, 41 ruthenium, 43 and iron. 41,44 Only one example of class B is known; it is a highly rigid ligand and does not permit mononuclear, chelated metal complexes, with only a silver complex being reported. 23 The more flexible skeletal structure of type C offers chelating abilities, 24,27,45 although the reported palladium complex is strongly distorted with N−Pd−N and N−Pd−C angles of 80°in comparison to C−Pd−C angles of 120°. 24 Acyclic tetra-NHC ligands (D) are highly flexible, and complexes are known for coinage metals, group 10 metals, and iron. 29,46 For macrocyclic ligands of type E and F a broad r...

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Application of Open Chain Tetraimidazolium Salts as Precursors for the Synthesis of Silver Tetra(NHC) Complexes

Cited by 40 publications

References 38 publications

Structural diversity of late transition metal complexes with flexible tetra-NHC ligands

Structural diversity of late transition metal complexes with flexible tetra-NHC ligands

Crystal structure of aquadichloridobis(1-((2-methyl-1H-imidazol-1-yl)methyl)-1H-benotriazole-κN)mercury(II), C₂₂H₂₄Cl₂HgN₁₀O

NHC Versus Pyridine: How “Teeth” Change the Redox Behavior of Iron(II) Complexes

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Application of Open Chain Tetraimidazolium Salts as Precursors for the Synthesis of Silver Tetra(NHC) Complexes

Cited by 40 publications

References 38 publications

Structural diversity of late transition metal complexes with flexible tetra-NHC ligands

Structural diversity of late transition metal complexes with flexible tetra-NHC ligands

Crystal structure of aquadichloridobis(1-((2-methyl-1H-imidazol-1-yl)methyl)-1H-benotriazole-κN)mercury(II), C22H24Cl2HgN10O

NHC Versus Pyridine: How “Teeth” Change the Redox Behavior of Iron(II) Complexes

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Crystal structure of aquadichloridobis(1-((2-methyl-1H-imidazol-1-yl)methyl)-1H-benotriazole-κN)mercury(II), C₂₂H₂₄Cl₂HgN₁₀O