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3,1,2,4-Benzothiaselenadiazines, 1,3,2,4-benzodithiadiazines and 1,2,4,3,5-benzotrithiadiazepines are synthesized from Ar–NSN–SiMe3 and chalcogen chlorides, and converted into Herz salts, radicals and molecular complexes, and S- and Se-Bunte salts.

Herein, we describe the synthesis of coordination compounds starting from carbohydrazide ((H2NHN)2C=O (CHZ)) and the Zn2+ salt of dinitramic acid (HDN), which are high-nitrogen substances that exhibit properties similar to those of a burning-rate inhibitor of pyrotechnic compositions. This study demonstrates that these compounds react with glyoxal to furnish adducts of metal–organic macrocyclic cages bearing the elements of carbohydrazide, complexing metals and the HDN anion, depending on the ratio of the starting reactants. The assembled macrocyclic cage has “host–guest” properties and is a safe container for the storage of HDN salts. X-ray crystallographic analysis of the resultant coordination compound, [Zn(chz)3(N(NO2)2)2]), indicated that the metal–ligand association occurs via the N and O atoms of carbohydrazide. The zinc salt of dinitramic acid, which is enclosed into adducts with a macrocycle, is thermally stable and insensitive to mechanical impacts. The complex zinc salt of dinitramide was shown herein to exhibit inhibitory activity towards the burning rate of pyrotechnic compositions.

A new approach is suggested herein for the synthesis of pyrazole derivatives by reacting 4-nitrosemicarbazide with acetylacetone. Additional studies were done on the reaction of acetylacetone with semicarbazide and its derivatives (4-aminosemicarbazide, methylsemicarbazide, and dimethylsemicarbazide). The study on the reaction with acetylacetone resulted in monocyclic 3,5-dimethyl-N-nitropyrazole-1-carboxamide, monocyclic 5-hydroxy-3,5-dimethyl-2-pyrazoline, and bicyclic bis(3,5-dimethylpyrazole-1-carbonyl)hydrazine, and conditions for the formation of acetone semicarbazone were identified. The structures of the resultant compounds were validated by physicochemical analytical methods, including X-ray diffraction. The computer-aided screening in the PASS prediction software discovered a high biological activity of the newly obtained compounds.

The Claisen–Schmidt condensation reaction of 3,5-diacetyl-2,6-dimethylpyridine with salicylic aldehyde in the presence of an acid unexpectedly afforded 1-((5S,11S)-2,5-dimethyl-11,12-dihydro-5H-5,11-epoxybenzo[7,8]oxocino[4,3-b]pyridin-3-yl)ethan-1-one as the product of intramolecular cyclization instead of α,β-unsaturated ketones (mono- or bis-azachalcones). The obtained 1-((5S,11S)-2,5-dimethyl-11,12-dihydro-5H-5,11-epoxybenzo[7,8]oxocino[4,3-b]pyridin-3-yl)ethan-1-one is a close nitrogen-containing structural analogue of natural inhibitors of HIV-1 integrase, namely integrastatins A and B, epicoccolide A and epicocconigrone A, containing a tetracyclic epoxybenzooxocine fragment. Substrate scope and mechanistic insights into the cyclization reaction were investigated. A possibility of selective oxidation of the methylene group of the oxocine ring with selenous acid to the carbonyl group was shown to prove structural similarity of the synthesized pyridine-containing analogs with the integrastatin scaffold.

The regularities and synthetic potentialities of the alkylation of 4(5)-nitro-1,2,3-triazole in basic media were explored, and new energetic ionic and nitrotriazole-based coordination compounds were synthesized in this study. The reaction had a general nature and ended with the formation of N1-, N2-, and N3-alkylation products, regardless of the conditions and reagent nature (alkyl- or aryl halides, alkyl nitrates, dialkyl sulfates). This reaction offers broad opportunities for expanding the variability of substituents on the nitrotriazole ring in the series of primary and secondary aliphatic, alicyclic, and aromatic substituents, which is undoubtedly crucial for solving the problems related to both high-energy materials development and medicinal chemistry when searching for new efficient bioactive compounds. An efficient methodology for the separation of regioisomeric N-alkyl(aryl)nitrotriazoles has been devised and relies on the difference in their basicity and reactivity during quaternization and complexation reactions. Based on the inaccessible N3-substitution products that exhibit a combination of properties of practical importance, a series of energy-rich ionic systems and coordination compounds were synthesized that are gaining ever-increasing interest for the chemistry of energy-efficient materials, coordination chemistry, and chemistry of ionic liquids.

The regularities and synthetic potentialities of the alkylation of 4(5)-nitro-1,2,3-triazole in basic media were explored, and new energetic ionic and nitrotriazole-based coordination compounds were synthesized in this study. The reaction had a general nature and ended with the formation of

A number of framework amides with a ginsenol backbone have been synthesized using the Ritter reaction. We named the acetamide as Ginsamide. A method was developed for the synthesis of the corresponding amine and thioacetamide. The new compounds revealed a high activity against H1N1 influenza, which was confirmed using an animal model. Biological experiments were performed to determine the mechanism of action of the new agents, a ginsamide-resistant strain of influenza virus was obtained, and the pathogenicity of the resistant strain and the control strain was studied. It was shown that the emergence of resistance to Ginsamide was accompanied by a reduction in the pathogenicity of the influenza virus.

The possibility of a single-stage solvent-free stereoselective synthesis of a spirocyclic compound from the natural bicyclic monoterpenoid (−)-fenchone and anthranilamide has been shown for the first time. The molecular and crystal structure of (1R,2S,4S)-1,3,3-trimethyl-1′H-spiro[bicyclo[2.2.1]heptane-2,2′-quinazolin]-4′(3′H)-one, C17H22N2O, was established by X-ray diffraction though the chirality was assumed via the known reactant connectivity and 1H and 13C NMR spectroscopy. It has shown that in the molecule, for steric reasons, there is an elongation of the Me2C—C(N)N bond to 1.603 (5) Å. The formation of dimers via N—H...O=C hydrogen bonds with an interaction energy of 93.30 kJ mol−1 and through cavities (33.7% of the unit-cell volume) was established in the packing of the molecules. There are no π-stacking interactions in the structure.

The unexpected formation of a highly strained polycyclic amine was observed in a one-pot synthesis from cyclopentanone, dimethyl fumarate and ammonium acetate. This multistep reaction includes 1,3-dipolar cycloaddition of dimethyl fumarate to the cyclic azomethine ylide formed in situ from cyclopentanone and ammonia. The polycyclic amine product was easily converted into a sterically shielded polycyclic nitroxide. The EPR spectra and spin relaxation behavior of the nitroxide were studied in solution. The spin relaxation seems well suited for the use as a biological spin label and are comparable with those of cyclic nitroxides with two spirocyclic moieties adjacent to the N–O· group.

Successive interaction of pentafluorobenzonitrile with resorcinol, orcinol and tetrafluororesorcinol in Et3N−CH3CN system gives fluorinated tetraoxacalix[4]arenes ABAB and ABAC type in a good yield. Further reaction of obtained products with new additional equivalent of tetrafluororesorcinol or orcinol leads to the formation of the fluorine-containing bicyclooxacalixarenes. The ESI-MS method shows the possibility of fluorinated tetraoxacalixarenes and bicyclooxacalixarenes complexes formation with metal cations.

Perfluorinated tetrathiacalix[4]arene was obtained by heating perfluoro-m-xylene with thiourea or 2,5-difluoro-4,6-bis(trifluoromethyl)benzene-1,3-dithiol at 90 &deg, C. Interaction of perfluoro-m-xylene with resorcinol or orcinol under mild conditions and subsequent heating of the mixture with 2,5-difluoro-4,6-bis(trifluoromethyl)benzene-1,3-dithiol leads to polyfluorinated dioxadithiacalix[4]arenes. Triphenyl and pentaphenyl ethers formed by the interaction of perfluoro-m-xylene with resorcinol under heating with thiourea gives polyfluorinated oxathiacalixarenes containing six and five aromatic nuclei, respectively.

We synthesized fluoro- and hydroxy-containing octahydro-2H-chromenes by the Prins reaction starting from a monoterpenoid (–)-isopulegol and a wide range of aromatic aldehydes in the presence of the BF3∙Et2O/H2O system acting as both an acid catalyst and a fluorine source. Activity of the produced compounds against the influenza A/Puerto Rico/8/34 (H1N1) virus was studied. The highest activity was demonstrated by fluoro- (11i) and hydroxy-containing (10i) derivatives of 2,4,6-trimethoxybenzaldehyde. The most pronounced virus-inhibiting effect of compounds 10i and 11i was observed at an early stage of infection. These compounds were supposed to be capable of binding to viral hemagglutinin, which is an agreement with data on the effect of compounds 10i and 11i on the viral fusogenic activity as well as by molecular docking studies.

A series of stable and genuinely organic open-shell systems, π-conjugated phenoxyl-nitroxide free radicals (hybrid phenoxyl-nitroxide radicals), have been synthesized and their magnetic properties in the crystalline state investigated, revealing their usefulness as new building blocks for molecular magnetic materials. The salient electronic structure of the hybrid phenoxyl-nitroxide radicals is extended π-spin delocalization from the nitroxide moiety, mediating the localization effect intrinsic to nitroxide radicals. Five representative hybrid radicals containing an aliphatic, aromatic, and heteroaromatic substituent in the side part of the compact hybrid radical centers were synthesized, and their molecular/crystal structures in the crystalline state were determined by X-ray diffraction analyses. CW X-band ESR, 1H-ENDOR spectroscopy, and DFT calculations for the hybrid radicals confirmed that an unpaired spin delocalizes over the whole molecular frame including the nonconjugated fragments, suggesting the possibility of tuning their electronic properties through substituent effects in the crystalline state. Significant influence of the phenoxyl moiety on the electronic structure was analyzed in terms of the g-tensor calculations. The SQUID magnetization measurements revealed that the nitroxides bearing alkyl or aromatic substituents behave as 3D Curie-Weiss paramagnets with weak antiferromagnetic (AFM) (Θ = -1 to -2.6 K) or ferromagnetic (FM) (Θ = +0.33 K) spin-spin exchange interactions. On the other hand, heteroaromatically substituted hybrid phenoxyl-nitroxide showed significant AFM interactions with J/kB = -25.6 K. The analysis of the bulk magnetic properties based on the crystallographic data and DFT calculations revealed competition between the intermolecular AFM and FM interactions which originate from the C-O(phenoxyl)···Me(nitroxide) or (N)O-C(arom) infinite 1D head-to-tail chains and the C(arom)-C(arom) head-over-tail dimers forming 3D networks in their crystal lattices.

1,1-Difluoronaphthalen-2(1H)-ones were used as building blocks for synthesis of functionalized fluorinated tetraphenones via Diels-Alder reaction. Two effective methods of tetraphenone reductive aromatization were proposed. Fully aromatic stable fluorinated tetraphene derivative with high solubility and HOMO-LUMO gap of 3.08 eV was obtained.

A simple method for the synthesis of sterically shielded pyrrolidine nitroxides, including the title compound, has been suggested. The key procedure implies assembling the pyrrolidine ring from α-amino acid, ketone, and activated alkene in a three-component domino process, followed by oxidation to nitrone and Grignard reagent addition. The new nitroxides demonstrate very high stability against reduction with ascorbate.

Birch's reductive alkylation of biphenyl-4-carbonitrile (1) provides alkylated 1,4-dihydroderivatives of various structural types: 4-alkyl-4-phenylcyclohexa-2,5-dienone, 1,4-dialkyl-4-phenylcyclohexa-2,5-dienecarbonitrile (with the same or different alkyl fragments), and 4-(1-alkylcyclohexa-2,5-dienyl)benzonitrile. Each of these products become dominant depending on the nature of long-living anionic form generated from 1, namely, the stable product of two-electrons reduction – dianion (12−); 1-alkyl-4-cyano-1-phenylcyclohexa-2,5-dien-4-yl anion (1-Alk1–), originated due to the alkylation of dianion 12− at the position 1 of biphenyl moiety; or 1-(4-cyanophenyl)cyclohexa-2,5-dien-1-yl anion (1-H4’–), being the product of dianion 12− protonation at position 4′ by protonating reagent (MeOH or NH4Cl). The orientation of alkyl fragment incorporation into biphenyl-4-carbonitrile scaffold is in agreement with calculated electronic structure of the anionic species under investigation. The dominating type of their reactivity towards alkyl halides proved to be nucleophilic (SN2 mechanism).

Two mononuclear iron(ii) complexes with isomeric N,N,N-tridentate pyrimidine-based ligands were synthesized. Both complexes show reproducible hysteretic spin crossover. Low spin state to high spin state switching is cooperative due to autocatalysis.

Interaction of perfluorotetralin with 1,2,3,4-tetrafluorobenzene (1 mol) in the presence of SbF5 at 50–55 °C gives, after treatment of the reaction mixture with HF–pyridine, perfluoro-1,2,3,10b-tetrahydrofluoranthene. When the reaction mixture was treated with water, perfluoro-5,6-dihydrofluoranthen-6a(4H)-ol was obtained. The reaction of perfluorotetralin with 2 moles of 1,2,3,4-tetrafluorobenzene leads, after treatment with H2O, to a mixture of perfluorinated 5,6-dihydrofluoranthen-6a(4H)-ol, 8,13-dihydro-7bH-8,13-methanobenzo[5,6]cyclohepta[1,2,3-jk]fluoren-7b-ol and 13-(2,3,4,5-tetrafluorophenyl)-perfluoro-8,13-dihydro-7bH-8,13-methanobenzo[5,6]cyclohepta[1,2,3-jk]fluoren-7b-ol. When 1-(2,3,4,5-tetrafluorophenyl)perfluorotetralin was dissolved in SbF5–SO2ClF, 1-(2,3,4,5-tetrafluorophenyl)perfluoro-1-tetralinyl cation was generated. The latter undergoes cyclization at ambient temperature to form perfluoro-1,2,3,10b-tetrahydrofluoranthen-10b-yl cation, which was also generated from perfluoro-1,2,3,10b-tetrahydrofluoranthene in a separate experiment.

Iron(II) hexafluorophosphate complexes with N,N,N-tridentate ligands, 2-(pyridin-2-yl)-4-(1H-pyrazol-1-yl)-6-methylpyrimidine (L(H,H)) and 2-(pyridin-2-yl)-4-(3,5-dimethyl-1H-pyrazol-1-yl)-6-methylpyrimidine (L(Me,Me)) were synthesized by reacting FeCl2·4H2O, (NBu4)PF6 and L(H,H) or L(Me,Me) in alcohol media. Supramolecular 3D structure of [FeL(H,H)2](PF6)2·nH2O is organized by CH…π interactions, π…π-stacking and CH…F hydrogen bonds. In the stricture of [FeL(Me,Me)2](PF6)2·nH2O the cations and anions are assembled into a 3D network via CH…F hydrogen bonds and lone pair…π interactions. Both complexes demonstrate high thermal stability. Under vacuum, the complex [FeL(Me,Me)2](PF6)2·nH2O is predominantly in the low spin state below 400 K, but at higher temperatures it shows gradual spin state switching which remains incomplete even at 495 K. Under vacuum or in sealed ampoule in the first heating run the complex [FeL(H,H)2](PF6)2·nH2O shows abrupt spin state switching related to dehydration near 400 K. On further thermal cycling under vacuum the complex demonstrates gradual spin crossover curve centered at ca. 250 K, whereas in sealed ampoules this compound demonstrates a very abrupt transition near 250 K.

Interaction of perfluoro-m-xylene with tetrafluororesorcinol in Et3N-CH3CN system leads to the formation of perfluorinated tetramethyltetraoxacalix[4]arene with a good yield, while the reaction with resorcinol gives a mixture of macrocycles containing 4, 6 or 8 aromatic rings. The intermediate products in these reactions are perfluoro-3-(2,4-dimethylphenoxy)phenol and 1,3-bis(2,4-bistrifluoromethyltrifluorophenoxy)benzene, respectively. The interaction of the latter with tetrafluororesorcinol leads to the formation of tetraoxacalix[4]arene of ABAC type with a good yield.

Interaction of perfluorinated 1,2-dialkylbenzocyclobutenes with CO–SbF5 at room temperature and perfluoro-1-methyl-2-phenylbenzocyclobutene at 50 °C gives fluoroindan-2-one derivatives. When reaction temperature is raised to 70 °C, polyfluorinated isochromene derivatives are formed in both cases. Interaction of perfluoro-1-ethyl-1-phenylbenzocyclobutene with CO–SbF5 at 70 °C gives, after treatment of the reaction mixture with H2O, perfluoro-3-ethyl-3-phenylindan-1,2-dione.

The system [FeL2](BF4)2 (1)-EtOH-H2O (L is 4-(3,5-dimethyl-1H-pyrazol-1-yl)-2-(pyridin-2-yl)-6-methylpyrimidine) shows a complicated balance between the relative stabilities of solvatomorphs and polymorphs of the complex [FeL2](BF4)2. New solvatomorphs, 1(LS)·EtOH·H2O and β-1(LS)·xH2O, were isolated in this system. They were converted into four daughter phases, 1(A/LS), 1(D/LS), 1(E/LS)·yEtOH·zH2O and 1(F/LS). On thermal cycling in sealed ampoules, the phases 1(LS)·EtOH·H2O and β-1(LS)·xH2O transform into the anhydrous phase 1(A/LS). The hysteresis loop width for the (A/LS) ↔ (A/HS) spin transition depends on the water and ethanol contents in the ampoule and varies from ca. 30 K up to 145 K. The reproducible hysteresis loop of 145 K is the widest ever reported one for a spin crossover complex. The phase 1(A/LS) combines the outstanding spin crossover properties with thermal robustness allowing for multiple cycling in sealed ampoules without degradation. The kinetics of the 1(A/LS) → 1(A/HS) transition is sigmoidal which is indicative of strong cooperative interactions. The cooperativity of the 1(A/LS) → 1(A/HS) transition is related to the formation of a 2D supramolecular structure of the phase 1(A/LS). The activation energy for the spin transition is very high (hundreds of kJ mol(-1)). The kinetics of the 1(A/HS) → 1(A/LS) transition can either be sigmoidal or exponential depending on the water and ethanol contents in the ampoule. The phases 1(D/LS) and 1(F/LS) show gradual crossover, whereas the phase 1(E/LS)·yEtOH·yH2O shows a reversible hysteretic transition associated with the solvent molecule release and uptake.

This study was focused on investigating the formation of N-polysulfonylsubstituted aza- and oxaazaisowurtzitanes via condensation of 4-dimethylaminobenzenesulfonamide with glyoxal and discovering new polyheterocyclic caged systems. More specifically, we explored how a donor substituent incorporated into the para position of the phenylsulfonamide molecule would influence the formation of cage products. Four new oxaazaisowurtzitane derivatives bearing one to three aza groups in the cage were consequently synthesized. A side reaction was found to take place, leading to a product having a non-isowurtzitane structure and four 4-dimethylaminobenzenesulfonyl moieties. The side product was analyzed by X-ray diffraction.

Cadmium(II) complexes, [CdLCl 2 ] n ( 1 ), α-{[CdLCl 2 ]·H 2 O} n ( 2 ), β-{[CdLCl 2 ]·H 2 O} n ( 3 ), and [Cd 4 L 2 (H 2 O) 2 Cl 8 ]·2H 2 O ( 4 ), with 3,5-bis(pyrimidin-2-yl)-4 H -1,2,4-triazol-4-amine (L), have been synthesized. They are the first examples of structurally characterized metal complexes with L. In these structures, the ligand L adopts either bidentate (N′ pyrimidine ,N 1 triazole ) or bis -bidentate (N′ pyrimidine ,N 1 triazole ,N 2 triazole ,N″ pyrimidine ) coordination. The complexes 1 – 3 are linear coordination polymers, the compounds 2 and 3 are polymorphs. The linear chains are assembled into 2D supramolecular structure due to π–π stacking interactions between practically planar L molecules. The structure of 4 consists of [Cd 4 L 2 (H 2 O) 2 Cl 8 ] complex molecules with μ 2 - and μ 3 -chlorido-bridged quasi-cubane tetracadmium core and non-coordinated water molecules. In the structure of 4 , the intermolecular lone pair–π interactions were observed between Cl atom and π-deficient triazole ring. The photoluminescent properties of L, 3 , and 4 were studied in the solid state. These compounds were found to display bright blue luminescence. The relative intensity of emission increases in the order L 4 L 2 (OH 2 ) 2 Cl 8 ]·2H 2 O 2 ]·H 2 O} n .

Although an interaction between hydrocarbon and fluorocarbon 1,3,2,4-benzodithiadiazines (1 ) and P(C6H5)3 continuously produces chiral 1,2,3-benzodithiadiazol-2-yl iminophosporanes (2; in this work, 5,7-difluoro derivative 2a ) via 1:1 condensation, an interaction between 1 and other PR3 reagents gives different products. With R OC6H5 and both hydrocarbon and fluorocarbon 1, only X=P(OC6H5)3 (X = S, O) were identified in the complex reaction mixtures by 13С and 31Р NMR and GC-MS. With R = C6F5, no interaction with the archetypal 1 was observed but catalytic addition of atmospheric water to the heterocycle afforded 2-amino-N-sulfinylbenzenesulfenamide (4 ). With electrophilic B(C6F5)3 instead of nucleophilic P(C6F5)3, only adduct H3NB(C6F5)3 and a new polymorph of C6F5B(OH)2 were isolated and identified by X-ray diffraction (XRD). A molecular structure of 2a was confirmed by XRD, and the π-stacked orientation of one of phenyl groups and heterocyclic moiety was observed. This structure is in general agreement with that calculated at the RI-MP2 level of theory, as well as at three different levels of DFT theory with the PBE and B3LYP functionals. Mild thermolysis of 2a in a dilute decane solution gave persistent 5,7-difluoro-1,2,3-benzodithiazolyl (3a ) identified by EPR in combination with DFT calculations.

Salts of 1,2,3-benzodithiazolium (1), 2,1,3-benzothiaselenazolium (3), and 1,2,3-benzodiselenazolium (4) (Herz cations), namely, [1][BF4], [1][SbCl6], [3][BF4], [3][GaCl4], [3][SbCl6], and [4][GaCl4], were prepared from the corresponding chlorides and NaBF4, GaCl3, or SbCl5. It was found that [1][SbCl6] and [3][SbCl6] spontaneously transform in MeCN solution to [1](3)[SbCl6](2)[0] and [3](3)[SbCl6](2)[Cl], respectively. [1][BF4], [1](3)[SbCl6](2)[Cl], [3][BF4], [3](3)[SbCl6](2)[Cl], and [4]-[GaCl4] were structurally characterized by X-ray diffraction (XRD). In solution, these [BF4](-) and [GaCl4](-) salts as well as [1][GaCl4], [2][GaCl4], [3][GaCl4], [3][Cl], and [4][Cl] were characterized by multinuclear nuclear magnetic resonance (NMR). The corresponding Hen radicals 1(center dot)-4(center dot) were obtained in toluene and DCM solutions by the reduction of the appropriate salts with Ph3Sb and characterized by EPR. Cations 1-4 and radicals 1(center dot)-4(center dot) were investigated computationally at the density functional theory (DFT) and second-order Moller-Plesset (MP2) levels of theory. The B1B95/cc-pVTZ method was found to satisfactorily reproduce the experimental geometries of 1-4; an increase in the basis set size to cc-pVQZ results in only minor changes. For both 1-4 and 1(center dot)-4(center dot), the Hirshfeld charges and bond orders, as well as the Hirshfeld spin densities for the radicals, were calculated using the B IB95/cc-pVQZ method. It was found for both the cations and the radicals that replacing S atoms with Se atoms leads to considerable changes in the atomic charges, bond lengths, and bond orders only at the involved and the neighboring sites. According to the calculations, 60% of the positive charge in the cations and 80% of the spin density in the radicals is localized on the heterocycles, with the spin density distributions being very similar for all radicals 1(center dot)-4(center dot). For the cations 1-4, the NICS values (B3LYP/cc-pVTZ for B1B95/cc-pVTZ geometries) lie in the narrow range from -5.5 ppm to -6.6 ppm for the carbocycles, and from -14.4 ppm to -15.5 ppm for heterocycles, clearly indicating the aromaticity of the cations. Calculations on radical dimers [1(center dot)](2)-[4(center dot)](2) revealed, with only one exception, positive dimerization energies, i.e., the dimers are inherently unstable in the gas phase.

A series of mono- and oligonuclear copper(II) complexes with new hybrid NNN-tridentate 4-(1 H -pyrazol-1-yl)-2-(pyridin-2-yl)pyrimidine ligands, 4-(1 H -pyrazol-1-yl)-2-(pyridin-2-yl)-6-methylpyrimidine (L 1 ) and 4-(3,5-dimethyl-1 H -pyrazol-1-yl)-2-(pyridin-2-yl)-6-methylpyrimidine (L 2 ), have been synthesized. The reaction of CuCl 2 with L 1 in EtOH in the 1:1 metal-to-ligand molar ratio affords the mononuclear complex [CuL 1 Cl 2 ]·0.5H 2 O ( 1 ). An increase of the metal-to-ligand molar ratio up to 4:1 as well as the use of less polar mixed solvent, EtOH/CHCl 3 , leads to mononuclear complex [CuL 1 Cl 2 ] ( 2 ). Attempts to crystallize di- or oligonuclear copper(II) complex with L 1 (the 8:1 metal-to-ligand molar ratio, EtOH/CHCl 3 ) resulted in the formation of ionic halocuprate compound, [Cu 7 L 1 4 Cl 12 ][Cu 2 Cl 6 ] ( 3 ), containing unique heptanuclear cation, [Cu 7 L 1 4 Cl 12 ] 2+ , and dinuclear anion [Cu 2 Cl 6 ] 2− . The reaction of CuCl 2 with L 2 in EtOH in the 1:1 metal-to-ligand molar ratio affords mononuclear complex [CuL 2 Cl 2 ] ( 4 ). Di- and tetranuclear complexes, [Cu 2 L 2 Cl 4 ] ( 5 ) and [Cu 4 L 2 2 Cl 8 ] ( 6 ), can be crystallized from ethanolic solution when the 2:1 metal-to-ligand molar ratio is used. The former is the product of kinetic control, while the latter is that of thermodynamic one. Being coordinated, the molecules of L 1 and L 2 adopt tridentate chelating coordination mode binding copper atoms through pyrazolyl N 2 , pyrimidine N 3 and pyridinyl N atoms and forming thus two five-membered chelate rings (CuN 3 C and CuN 2 C 2 ). Depending on the metal-to-ligand molar ratio in the solution, electrospray ionization mass spectrometry (ESI-MS) evidenced the presence of mono- and oligonuclear copper species in the CuCl 2 –L 1 and CuCl 2 –L 2 solutions. The isolation of oligonuclear species in the solid state seems to be related with the absence of hydrogen-bond donor groups in the molecules of 4-(1 H -pyrazol-1-yl)-2-(pyridin-2-yl)pyrimidine ligands.

Efficient methods for the preparation of 1-hydroxy-1,5-dihydro-2H-pyrrol-2-ones and 1-hydroxy-1,6-dihydropyridine-2,5-diones from N-hydroxy-N-(2-oxoalkyl)amides are reported. It was found that the reaction of N-hydroxy-N-(2-oxoalkyl)amides with 3 equiv of potassium tert-butoxide led to 1-hydroxy-1,5-dihydro-2H-pyrrol-2-ones. A decrease of the base content to 1.5 equiv or less led to an increase of 1-hydroxy-3-phenyl-1,6-dihydropyridine-2,5-dione in the reaction due to oxidation of the starting materials by atmospheric oxygen and their subsequent transformation.

A condensation between mesylamide and glyoxal under highly acidic conditions was studied. A series of new compounds whose structures contain a moiety of oxaazatetracyclo[5.5.0.03,11.05,9]dodecane were synthesized. The synthesis processes were optimized and main factors affecting the assembling of cage products were revealed. Assumptions are made regarding the formation mechanism of these chemical entities. For the first time, compounds have been obtained that include moieties of 2,6,8-trioxa-4,10,12-triazatetracyclo[5.5.0.03,11.05,9]dodecane and 2,4,6-trioxa-8,10,12-triazatetracyclo[5.5.0.03,11.05,9]dodecane. An X-ray diffraction analysis of the new compounds was performed.

The reaction of 2,3-diaminomaleonitrile with TeX4 (X = Cl, Br) in the presence of pyridine (Py) and/or triethylamine (Et3N) provided 3,4-dicyano-1,2,5-telluradiazole (1), which was isolated neat and as stable adducts with pyridine, chloride, and bromide, namely, 1·2Py, (PyH)(1·Cl), (PyH)2(1·2Cl), (Et3NH)(1·Cl), (PyH)(1·Br), and (PyH)2(1·2Br). The molecular and supramolecular structures of these compounds were investigated by X-ray crystallography. In the solid state, intermolecular associations through secondary Te···N interactions as well as N–H···X and N–H···N hydrogen bonding (X = Cl, Br) were observed. For (PyH)(1·Br), two polymorphs were found. The bonding situation of 1 and its pyridine and chloride adducts were investigated by MP2 calculations supplemented with the quantum theory of atoms in molecules (QTAIM) and natural bond orbital (NBO) analyses. The π symmetry of the frontier molecular orbitals (MOs) of 1 are preserved in the 1·2Py, (1·Cl–), and (1·2Cl–) adducts. In the chloride adducts, the highest occupied molecular orbital (HOMO) can be described as an antibonding combination of the HOMO of 1 with the 3p atomic orbitals (AOs) of the chloride ions, whereas the lowest occupied molecular orbital (LUMO) resembles that of the parent 1. The charge transfer onto the heterocycle in the adducts increases in the order 1·2Py, (1·2Cl–), and (1·Cl–). QTAIM analyses of the adducts in the gas phase reveal closed-shell interactions, whereas NBO analyses indicate negative hyperconjugation as the main formation pathway in these complexes. This description agrees with the Alcock model suggested for secondary bonding interactions between atoms of heavy p-block elements and atoms with lone pairs.