Synthesis and structure of 5,7-Di(<Emphasis Type="Italic">tert</Emphasis>-butyl)-2-(8-methanesulfonyloxyquinolin-2-yl)-1,3-tropolone

5,7-Di(tert-butyl)-2-(8-methanesulfonyloxyquinolin-2-yl)-1,3-tropolone whose structure was established by X-ray diffraction analysis and confirmed by ¹H and ¹³C NMR, IR spectroscopy, and mass spectrometry, was obtained by the reaction of 2-methyl-8-methanesulfonyloxyquinoline with 3,5-di(tert-butyl)-1,2-benzoquinone. According to X-ray diffraction study, this sulfonyloxyquinolinotropolone exists in the NH tautomeric form with methanesulfonyloxy group in the exo position to the tropolone ring and the sixmembered chelate ring produced by the quinoline and tropolone moieties stabilized by strong intramolecular hydrogen bond. The strong intramolecular hydrogen bond between the phenolic oxygen atom and the six-membered chelate ring provides supplementary contribution to the stabilization of the NH tautomeric form.     

Absorption and luminescence spectra of 5-aryl-3-methyl-1,2,4-oxadiazoles and their chelate complexes with Zinc(II) and copper(II)

5-(2-Hydroxyphenyl)-3-methyl-1,2,4-oxadiazole and its O-methyl and O-acyl derivatives, as well as zinc(II) and copper(II) chelates, were synthesized. All these compounds showed luminescence with the emission maxima ranging from λ = 332 to 490 nm, but only 5-(2-methoxyphenyl)- and 5-(2-acetoxyphenyl)-3-methyl-1,2,4-oxadiazoles and zinc(II) complex of 5-(2-hydroxyphenyl)-3-methyl-1,2,4-oxadiazole were characterized by high luminescence quantum yield (φ = 0.308–0.452, 0.089–0.153, and 0.115–0.334, respectively). Stable conformers of 5-(2-hydroxyphenyl)-3-methyl-1,2,4-oxadiazole with different structures of the coordination entity were identified by DFT quantum chemical calculations.     

Spectral luminescent properties of 2-(2-hydroxyphenyl)-5-methyl-1,3,4-oxadiazole and its acetyl(benzoyl)oxy derivatives

Russian Journal of Organic Chemistry -     

Theoretical and experimental studies on the structure and isomerization of isocyano and cyano cyclopolyenes

Quantum-chemical calculations in terms of the density functional theory showed that cyclopolyenyl isocyanides RNC are considerably less stable than the corresponding cyanides and that they are capable of undergoing RNC → RCN isomerization according to both 1,2-shift mechanism (cyclopropenyl and cyclopentadienyl isocyanides; ΔE ^≠ = 35.0 and 37.5 kcal/mol, respectively) and previously unknown 2,5-sigmatropic shift mechanism (cycloheptatrienyl isocyanide, ΔE ^≠ = 26.4 kcal/mol). Migration of cyano group in the cyclopentadiene and cycloheptatriene systems follows the 1,5-sigmatropic shift pattern. The activation barrier to 1,5-shift of cyano group around the cycloheptatriene ring was estimated by dynamic NMR in deuterated nitrobenzene (ΔG _190°C ^≠ = 26.5 kcal/mol).     

Structure and Rearrangements of 7-(Heptaphenylcycloheptatrienyl)isochalcogencyanates

According to DFT B3LYP/6-31G(d,p) calculations, the intramolecular migration of NCX groups (X = O, S, Se, Te) in 7-(heptaphenylcycloheptatrienyl)isochalcogencyanates in the gas phase proceeds via the dissociation–recombination mechanism. Structures were found of transition states preceding the formation of tight ion pairs. High activation barriers to the migration of isochalcogencyanate groups (\(\Delta E{^\neq_{\rm{ZPE}}}\) 26.7, 21.3, 20.5, 19.3 kcal mol^–1) originate from the existence of stable conformation of molecules with NCX groups located in the equatorial position and are in agreement with the data of dynamic NMR. For the transition of the molecule in the form favorable for the NCX group migration an inversion of the seven-membered ring and the rotation of the phenyl group are necessary.     

Structure and Fluxional Behavior of Phenylmercury Derivatives of N,N'-Diarylform(benz)amidines

Activation barriers for fast 1,3-N,N' migrations of phenylmercury groups in the corresponding derivatives of N,N'-di(p-tolyl)form(benz)amidines have been calculated by density functional theory B3LYP/Gen, 6-311++G(d,p)/SDD to be ΔE _ZPE ^≠ = 4.5 and 3.0 kcal/mol. The results correspond to the data of dynamic NMR, which have shown the upper limit of activation barriers of these rearrangements (ΔG^≠) to be below 8 kcal/mol. The calculations have shown that the most stable is the E-syn form of N-phenylmercury-N,N'-di(p-tolyl)form(benz)amidines stabilized by supplementary intramolecular coordination of mercury atom with imine nitrogen atom of the amidine triad.     

Conditions of the Formation of a Shock Wave under Cavitation in Hydrocarbon Solutions

Doklady Physics - We carried out a numerical study of the appearance of a shock wave during the collapse of a bubble in a hydrocarbon aqueous solution. The conditions for the appearance of a shock...     

Synthesis and Spectral-Luminescent Properties of 2,5-Diaryl-1,3,4-oxadiazoles and Their Chelate Complexes with Cadmium(II)

Russian Journal of General Chemistry - Cyclization of N′-(arylcarbonyl)benzohydrazides in SOCl2 has afforded 2-aryl-5-(4-octyloxyphenyl)-1H-1,3,4-oxadiazoles; the spectral-luminescent...