- When Donors Turn into Acceptors: Ground and Excited State Properties of FeII Complexes with Amine-Substituted Tridentate Bis-imidazole-2-ylidene Pyridine Ligands
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In search of new ligand motifs for photoactive iron(II) complexes with long-lived MLCT states, a series of six complexes with tridentate amine-functionalized bis-n-heterocyclic carbene (NHC)-pyridine ligands is presented. In the homoleptic complexes imidazole-, methylimidazole-, or benzimidazole-2-ylidene, NHC donors are employed in combination with pyridine, functionalized in the 4-position by dimethylamine or dibenzylamine. The effects of these different functionalities on the electronic structure of the complexes are examined through detailed ground state characterization by NMR, single crystal X-ray diffraction, as well as electrochemical and spectroscopic methods. The net influence of these different functionalities on orbital-orbital and electrostatic ligand-iron interactions is investigated thoroughly by density functional theory, and changes in the excited state behavior and lifetimes are finally examined by ultrafast optical spectroscopy. Great deviations of the initially expected effects by substitution in 4-position on the photochemical properties are observed, together with a significantly increased -acceptor interaction strength in the benzimidazole-2-ylidene functionalized complexes.
- Altenburger, Bj?rn,Bauer, Matthias,Burkhardt, Lukas,Fritsch, Lorena,Lochbrunner, Stefan,Miletic, Anabel,Neuba, Adam,P?pcke, Ayla,Schoch, Roland,Vukadinovic, Yannik
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- Synthesis, Characterization, and DFT Analysis of Bis-Terpyridyl-Based Molecular Cobalt Complexes
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Terpyridine ligands are widely used in chemistry and material sciences owing to their ability to form stable molecular complexes with a large variety of metal ions. In that context, variations of the substituents on the terpyridine ligand allow modulation of the material properties. Applying the Stille cross-coupling reaction, we prepared with good yields a new series of terpyridine ligands possessing quinoline-type moieties in ortho, meta, and para positions and dimethylamino substituents at central or distal positions. The corresponding cobalt(II) complexes were synthesized and fully characterized by elemental analysis, single-crystal X-ray crystallography, mass spectrometry, and UV-vis, 1H NMR, and Fourier transform infrared (FT-IR) spectroscopy as well as by cyclic voltammetry (CV). Density functional theory (DFT) calculations were performed to investigate the electronic structure of all the Co(II) bis-terpyridyl molecular complexes. In this work, we show that terpyridine ligand functionalization allows tuning the redox potentials of the Co(III)/Co(II), Co(II)/Co(I), and Co(I)/Co(I) (tpy)?- couples over a 1 V range.
- Aroua, Safwan,Todorova, Tanya K.,Hommes, Paul,Chamoreau, Lise-Marie,Reissig, Hans-Ulrich,Mougel, Victor,Fontecave, Marc
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supporting information
p. 5930 - 5940
(2017/05/22)
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- Stereo- and Regioselective Alkyne Hydrometallation with Gold(III) Hydrides
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The hydroauration of internal and terminal alkynes by gold(III) hydride complexes [(C^N^C)AuH] was found to be mediated by radicals and proceeds by an unexpected binuclear outer-sphere mechanism to cleanly form trans-insertion products. Radical precursors such as azobisisobutyronitrile lead to a drastic rate enhancement. DFT calculations support the proposed radical mechanism, with very low activation barriers, and rule out mononuclear mechanistic alternatives. These alkyne hydroaurations are highly regio- and stereospecific for the formation of Z-vinyl isomers, with Z/E ratios of >99:1 in most cases.
- Pintus, Anna,Rocchigiani, Luca,Fernandez-Cestau, Julio,Budzelaar, Peter H. M.,Bochmann, Manfred
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p. 12321 - 12324
(2016/10/13)
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- Ligand-promoted ortho-C-H amination with Pd catalysts
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2,4,6-Trimethoxypyridine is identified as an efficient ligand for promoting a Pd-catalyzed ortho-C-H amination of both benzamides and triflyl-protected benzylamines. This finding provides guidance for the development of ligands that can improve or enable PdII-catalyzed Csp2-H activation reactions directed by weakly coordinating functional groups.
- Zhu, Dajian,Yang, Guoqiang,He, Jian,Chu, Ling,Chen, Gang,Gong, Wei,Chen, Ke,Eastgate, Martin D.,Yu, Jin-Quan
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supporting information
p. 2497 - 2500
(2015/02/19)
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- COMPOUNDS FOR THE TREATMENT OF PARAMOXYVIRUS VIRAL INFECTIONS
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Disclosed herein are new antiviral compounds, together with pharmaceutical compositions that include one or more antiviral compounds, and methods of synthesizing the same. Also disclosed herein are methods of ameliorating and/or treating a paramyxovirus viral infection with one or more small molecule compounds. Examples of paramyxovirus infection include an infection caused by human respiratory syncytial virus (RSV).
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Paragraph 0705
(2014/03/25)
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- Regiochemically flexible substitutions of di-, tri-, and tetrahalopyridines: The trialkylsilyl trick
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(Chemical Equation Presented) 2,4-Difluoropyridine, 2,4-dichloropyridine, 2,4,6-trifluoropyridine, 2,4,6-trichloropyridine and 2,3,4,6-tetrafluoropyridine react with standard nucleophiles exclusively at the 4-position under halogen displacement. However, the regioselectivity can be completely reversed if a trialkylsilyl group is introduced in the 5-position of the 2,4-dihalopyridines or in the 3-position of the 2,4,6-trihalopyridines or 2,3,4,6-tetrahalopyridine. Then only the halogen most remote from the bulky silyl unit (at the 2-position in the case of the 2,4-halopyridines, at the 6-position with the other substrates) gets involved in the exchange process. After removal of the silyl protective group the nucleophile is invariably found to occupy the nitrogen-neighboring position.
- Schlosser, Manfred,Bobbio, Carla,Rausis, Thierry
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p. 2494 - 2502
(2007/10/03)
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