Bis[2-(hy­droxy­imino­meth­yl)phenolato]nickel(II): a second monoclinic polymorph

The title compound, [Ni(C7H6NO2)2], (I), is a second monoclinic polymorph of the compound, (II), reported by Srivastava et al. [Acta Cryst. (1967), 22, 922] and Mereiter [Private communication (2002) CCDC refcode NISALO01]. The bond lengths and angles are similar in both structures. The mol­ecule in both structures lies on a crystallographic inversion center and both have an inter­nal hydrogen bond. The title compound crystallizes in the space group P21/c (Z = 2), whereas compound (II) is in the space group P21/n (Z = 2) with a similar cell volume but different cell parameters. In both polymorphs, mol­ecules are arranged in the layers but in contrast to the previously published compound (II) where the dihedral angle between the layers is 86.3°, in the title polymorph the same dihedral angle is 29.4°. The structure of (I) is stabilized by strong intra­molecular O—H⋯O hydrogen bonding between the O—H group and the phenolate O atom

Anionic lanthanide complexes with 3-methyl-1-phenyl-4-formylpyrazole-5-one and hydroxonium as counter ion

AbstractA series of [H3O]+[LnL4]−·nH2O complexes (n=1–3, Ln=Nd, (1), Sm (2), Eu (3), Tb (4); HL=3-methyl-1-phenyl-4-formylpyrazole-5-one) were synthesized and characterized. The structures of the SmIII and EuIII complexes were investigated by X-ray diffraction. The isostructutal crystalls 2 and 3 consist the tetrakis [LnL4]− anions which are linked by H-bonding with the hydroxonium counter-ion and water molecules. The lanthanide ion is situated in the center of distorted tetragonal antiprism formed by eight oxygen atoms of 4-formyl-5-hydroxypyrazolonate anions. The TbIII and SmIII complexes show strong luminescence in solid state, whereas the EuIII and NdIII complexes show low luminescence activity

Regioselective synthesis of bicyclic 1,3,5-triazepine system starting from tetrachloro-2-aza-1,3-butadienes

Readily available tetrachloro-2-aza-1,3-butadienes enter into directed cyclocondensation reaction with N-phenyl-1,2-cyclopentanediamine which leads to regioselective cyclopentane annulation by the 1,3,5-triazepine. The formation of the 1,3,5-triazepine derivatives was confirmed proved by 1H- and 13C-NMR spectral study, elemental analysis and, in one case, single-crystal x-ray crystallographic study

Novel unsymmetrically functionalized BEDT–TTF derivatives: synthesis, crystal structure and electrochemical characterization

Novel functionalized bis(ethylenedithio)tetrathiafulvalene (BEDT–TTF) derivatives 4 and 5 have been synthesized in good yields from cyano precursor via a cross-coupling reaction. Their redox potentials have been studied by cyclic voltammetry in a dichloromethane solution; this indicated that they are slightly weaker electron donors than BEDT–TTF. Compound 4 has been studied by X–ray crystallography; this revealed that, in the crystal, the molecules were held together by some unconventional C–H···N and C–H···S hydrogen bonds

Dichlorophosphoranides Stabilized by Formamidinium Substituents

Dichlorophosphoranides featuring N,N-dimethyl-N′-arylformamidine substituents were isolated as individual compounds. Dichlorophosphoranide 9 was prepared by the multicomponent reaction of C-trimethylsilyl-N,N-dimethyl-N′-phenylformamidine and N,N-dimethyl-N′-phenylformamidine with phosphorus trichloride. Its molecular structure derived from a single-crystal X-ray diffraction was compared to the analogous dibromophosphoranide prepared previously by us by the reaction of phosphorus tribromide with N,N-dimethyl-N′-phenylformamidine. It was shown that a chlorophosphine featuring two N,N-dimethyl-N′-mesitylformamidine substituents reacted with hydrogen chloride to form dichlorophosphoranide 11. Its molecular structure was also determined by X-ray analysis and compared with that of closely related dichlorophosphoranide C

Molecular and electronic structure of 1,3,2-diazaphosphinine derivatives

<p>Structure of 1,3,2-diazaphosphinine heterocyclic system was studied using quantum chemical calculations and X-ray diffraction method for one derivative. It was found that two P–N single bonds were different in their nature: one of them turned out to be significantly shorter and stronger, whereas the other one is longer and more diffused. The found effect is strengthened by π-donor substituents. The effect was interpreted by equilibrium of Lewis structures and analyzing the charge distribution by the NBO approach. The observed effect can be considered as the special form of π-conjugation in the heterocycles with the phosphorus (V) atom included.</p

Staightforward Synthesis of Halopyridine Aldehydes via Diaminomethylation

Koidan G, Zahorulko S, Hurieva A, et al. Staightforward Synthesis of Halopyridine Aldehydes via Diaminomethylation. Chemistry - A European Journal. 2023: e202301675.A novel two-step method for formylation of fluoropyridines with silylformamidine 1 under catalyst-free conditions was developed. A series of possible 18 fluoropyridines featuring one to four fluorine atoms were subjected to the reaction with 1 existing in equilibrium with its carbenic form 1'.12 Fluoropyridines were shown to react via C-H insertion. The reaction proceeded either at beta- or gamma-positions affording the corresponding aminals. The more fluorine atoms in pyridines, the easier the reaction proceeded. We also hypothesized that the pyridines in which the fluorine was substituted by other halogens would react in a similar manner. To test the hypothesis, a set of 3,5-disubstituted pyridines with various combination of halogen atoms was prepared. 3,5-Difluoropyridine was taken as a compound for comparison. All the pyridines in the series also reacted likewise. In most cases, hydrolysis of the aminals afforded the corresponding aldehydes. As DFT calculations indicate, the reaction mechanism includes deprotonation of pyridine by 1' as a strong base and the following rearrangement of the formed tight ionic pair to the final product. An alternative reaction pathway involving addition of 1' to the pyridine carbon with the following hydrogen transfer via a three-membered transition state structure required much higher activation energy. © 2023 Wiley-VCH GmbH