27832-35-5Relevant articles and documents
Synthesis, Structure, and Catalytic Hydrogenation Activity of [NO]-Chelate Half-Sandwich Iridium Complexes with Schiff Base Ligands
Lv, Wen-Rui,Li, Rong-Jian,Liu, Zhen-Jiang,Jin, Yan,Yao, Zi-Jian
, p. 8181 - 8188 (2021/05/26)
A series of N,O-coordinate iridium(III) complexes with a half-sandwich motif bearing Schiff base ligands for catalytic hydrogenation of nitro and carbonyl substrates have been synthesized. All iridium complexes showed efficient catalytic activity for the hydrogenation of ketones, aldehydes, and nitro-containing compounds using clean H2 as reducing reagent. The iridium catalyst displayed the highest TON values of 960 and 950 in the hydrogenation of carbonyl and nitro substrates, respectively. Various types of substrates with different substituted groups afforded corresponding products in excellent yields. All N,O-coordinate iridium(III) complexes 1-4 were well characterized by IR, NMR, HRMS, and elemental analysis. The molecular structure of complex 1 was further characterized by single-crystal X-ray determination.
Tautomerism in hydroxynaphthaldehyde anils and azo analogues: A combined experimental and computational study
Fabian, Walter M.F.,Antonov, Liudmil,Nedeltcheva, Daniela,Kamounah, Fadhil S.,Taylor, Peter J.
, p. 7603 - 7612 (2007/10/03)
The enol imine ? enaminone tautomerization constants, K T, and thermodynamic parameters, ΔHT and ΔST, of 1-hydroxy-2-naphthaldehyde Schiff bases are determined by UV/vis spectroscopy. Polar solvents shift the equilibrium toward the quinone form (for the unsubstituted derivative 1c, KT = 0.20 (cyclohexane) and KT = 1.49 (ethanol)). Both donor (MeO, NMe2) and acceptor (CN, NO2) substituents lead to a decreased KT independent of solvent polarity. In apolar solvents, for all derivatives 1a-1e, the enol imine ? enaminone equilibria are endergonic but exothermic. Linear solvation energy relationships allow extrapolation of ΔG T to the gas phase. Density functional theory calculations (B3LYP/6-311+G**) yield good agreement with these extrapolated ΔGT values. Solvent effects on le are also successfully reproduced by the calculations. Geometric (0...N distance) and energetic criteria (conformer energy differences, homodesmotic reactions) establish the importance of intramolecular hydrogen bonding for the tautomerism of these compounds. The results obtained for 1a-1e are compared with tautomeric properties of the isomeric naphthaldehyde anils 2-4, the monocyclic analogues 5 and 6, the corresponding azo derivatives 7-9, and the N-alkyl derivative 10.
