- Role of the X Coligands in Cyclometalated [Ni(Phbpy)X] Complexes (HPhbpy = 6-Phenyl-2,2′-bipyridine)
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The coligand X was varied in the organonickel complexes [Ni(Phbpy)X] (X = F, Cl, Br, I, C6F5) carrying the anionic tridentate CNN ligand 6-(phen-2-ide)-2,2′-bipyridine (Phbpy-) to study its effect on electronic structures of these complexes and their activity in Negishi-like C-C cross-coupling catalysis. The complexes were synthesized from the precursor [Ni(COD)2] (COD = 1,5-cyclooctadiene) by chelate-assisted oxidative addition into the phenyl C-X bond of the protoligand 6-(2-halidophenyl)-2,2′-bipyridine) and were obtained as red powders. Protoligands X-Phbpy carrying the halide surrogates X = OMe, OTf (triflate) failed in this reaction. Single-crystal XRD allowed us to add the structures of [Ni(Phbpy)Cl] and [Ni(Phbpy)I] to the previously reported Br derivative. Cyclic voltammetry showed reversible reductions for X = C6F5, F, Cl, while for Br and I the reversibility is reduced through rapid splitting of X- after reduction (EC mechanism). UV-vis spectroelectrochemistry confirmed the decreasing degree of reversibility along the series C6F5 > F > Cl ? Br > I, which parallels the "leaving group character"of the X coligands. This method also revealed mainly bpy centered reduction and essentially Ni(II)/Ni(III) oxidations, as corroborated by DFT calculations. The rather X-invariant long-wavelength UV-vis absorptions and excited states were analyzed in detail using TD-DFT and were consistent with predominant metal to ligand charge transfer (MLCT) character. Initial catalytic tests under Negishi-like conditions showed the complexes to be active as catalysts in C-C cross-coupling reactions but did not display marked differences along the series from Ni-F to Ni-I.
- Chin, Mason T.,H?rner, Gerald,Klein, Axel,Kletsch, Lukas,Sandleben, Aaron,Sch?fer, Sascha,Vicic, David A.,Vogt, Nicolas
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p. 1776 - 1785
(2021/06/28)
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- A novel antifungal agent with broad spectrum: 1-(4-Biphenylyl)-3-(1H- imidazol-1-yl)-1-propanone
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A series of (1-substituted aryl)-3-(1H-imidazol-1-yl)-1-propanones was synthesized through the N-alkylation of imidazole with 3-dimethylamino-1- (substituted aryl)-1-propanone hydrochlorides (ketonic Mannich bases). A second series of N1-substituted imidazoles was obtained by the reduction of the carbonyl function of the imidazole-ketones in the previous series by means of NaBH4. All of the compounds were evaluated for antifungal activity against 16 strains of Candida, and 3-(1H-imidazol-1-yl)-1-(4-biphenylyl)-1- propanone emerged as a broad-spectrum antifungal agent. Several 3-(1H-imidazol-1-yl)-1-(2′-(substituted benzyl)oxyphenyl)-1-propanones were also active towards Candida kefyr. Copyright
- Roman, Gheorghe,Mare?, Mihai,Nǎstasǎ, Valentin
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p. 110 - 118
(2013/04/10)
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- A Modified Synthesis of 4-Chromanones
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Problems in the synthesis of 4-chromanones by condensation of 2-hydroxyacetophenones with formaldehyde can be avoided by the isolation of the Mannich base hydrochlorides and cyclization by titration with potassium hydroxide.
- Cox, Brian,Waigh, Roger D.
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p. 709 - 710
(2007/10/02)
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- N-Vinylimidazoles and -triazoles and pharmaceutical compositions containing them
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Described are N-vinylazoles of the general formula: (wherein R is hydrogen, hydroxy, halogen, C1-C5 alkoxy, C2-C5 alkenyloxy, optionally substituted benzyloxy, tetrahydropyranyl-oxy, difluoromethoxy, 2-(2,4-dich
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- Synthesis and Antifungal Activity of New 1-Vinylimidazoles
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Carbonyl compounds I were subjected to an imidazole transfer reaction with N,N'-sulfinyldiimidazole or N,N'-carbonyldiimidazole to obtain the diimidazole II and the monoimidazole III.Various 1-vinylimidazoles IV, derived from o-hydroxyacetophenones by imi
- Ogata, Masaru,Matsumoto, Hiroshi,Shimizu, Sumio,Kida, Shiro,Shiro, Motoo,Tawara, Katsuya
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p. 1348 - 1354
(2007/10/02)
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