Theoretical predictions of the nitrogen heterocyclic compounds with metal and noble gas (metal = Cu,Ag, Au)

Here, we report a new type of Ng-containing compounds formed between the Ng-M group and nitrogen heterocyclic compounds, (CH₂)_nHNCuNg⁺ (n = 2, 3), (CH)₄NMNg, and (CH)₅NCuNg⁺ (M = Cu, Ag, Au; Ng = Ar, Kr, Xe). Quantum chemistry computations were carried out to optimize their geometric structures and calculate the dissociation energies, dissociation enthalpy, and dissociation free energy change. The stability of these Ng-bonding complexes was inspected by investigating the three dissociation processes of the these compounds into (a) Ng, M, and nitrogen heterocycle C_nN; (b) C_nN + MNg⁺; and (c) C_nNM + Ng, which are all endothermic and nonspontaneous, these dissociation processes are also turned out to be endergonic in nature at standard state. The natural bond orbital, atoms in molecules, and energy decomposition analysis based on the molecular wavefunction show that the M-Ng and M-N bonds have some covalent and electrostatic characters.     

Substitution reaction of η5-cyclopentadienylruthenium(II) complexes with nitrogen,oxygen and sulfur donor ligands

The heterocycles pyridine, γ-picoline, 2,2′-bipyridine and 1,10-phenanthroline react with [(η⁵-C₅H₅)Ru(MPh₃)₂X] (M = P, As or Sb) and [(η⁵-C₅H₅)Ru(AsPh₃)(PPh₃)X] (X = Cl, Br, I, CN, NCS or SnCl₃) to form complexes of types [(η⁵-C₅H₅)(MPh₃)(L−L)⁺X⁻ (L−L = 2,2′−bipyridine or 1,10−phenanthroline; X = Cl, Br, I, CN, NCS or SnCl₃) and [(η⁵-C₅H₅)Ru(MPh₃)LX] (M = As or Sb; L = pyridine or γ-picoline; X = Cl, Br, I, CN, NCS or SnCl₃). Interactions of dithiocarbamate (DTC) with [(η⁵-C₅H₅)Ru(SbPh₃)₂X] (X = Cl, Br or I) and acetylacetonate (acac) with parent compounds [(η⁵-C₅H₅)Ru(MPh₃)₂X (M = P or Sb; X = Cl, Br or I) yielded [(η⁵-C₅H₅)Ru(MPh₃)L] (where L = DTC or acac). The reaction products have been characterized by magnetic, spectral and microanalytical data.     

Relative molar responses of some compounds containing oxygen and nitrogen in GC–MS

Relative molar responses (RMRs) of some straight-chain aliphatic alkanes, ketones, aldehydes, alcohols, carboxylic acids, primary amines, aniline, and nitrobenzene derivatives were investigated related to naphthalene. Most of the respective compounds have not been investigated yet due to their high polarity or high boiling point. The earlier cross section data for oxygenated compounds were changed to RMRs which are more utilizable from an analytical aspect. A linear correlation was found between the RMRs and the carbon atom numbers in primary amines. In the cases of aniline and nitrobenzene derivatives the RMRs were also determined; however, no functional relationship was found. The measurement conditions, i.e., the type of column affect the apparent RMRs of aliphatic primary amines. A midpolar column having a higher maximum operating temperature provides a more sensitive apparent RMR (Rtx-1701) than the basic polar column having a lower maximum temperature (Stabilwax-DB), because a high temperature allows setting a higher injector temperature and a higher amount of compound can reach the ion source. Knowing correlations the quantitative analysis passes into easier and fewer reference materials are needed to investigate a sample having many components, because the sensitivities can be determined from the correlations studied in this paper. This is also valid for aromatic compounds, even though no functional relationship exists.     

Isolated diatomic Zn-Co metal–nitrogen/oxygen sites with synergistic effect on fast catalytic kinetics of sulfur species in Li-S battery

Lithium-sulfur batteries are severely restricted by low electronic conductivity of sulfur and Li2S, shuttle effect, and slow conversion reaction of lithium polysulfides(LiPSs). Herein, we report a facile and highyield strategy for synthesizing dual-core single-atom catalyst(ZnCoN₄O₂/CN) with atomically dispersed nitrogen/oxygen-coordinated Zn-Co sites on carbon nanosheets. Based on density functional theory(DFT)calculations and LiPSs conversion catalytic ability, ZnCoN_...     

A general,Brønsted acid-catalyzed hetero-Michael addition of nitrogen,oxygen, and sulfur nucleophiles

[reaction: see text] Strong Br?nsted acids such as bis(trifluoromethanesulfon)imide catalyze the hetero-Michael addition of carbamates, alcohols, and thiols to alpha,beta-unsaturated ketones, alkylidene malonates, and acrylimides. Scope, reaction rates, and yields are superior to comparable Lewis acid-catalyzed processes.     

Syntheses and structures of metal–metal triply bonded M2R6 compounds: consideration of starting materials,stability, and structural parameters

The syntheses and structures of four homoleptic metal–metal triply-bonded M₂R₆ compounds [Mo₂(CH₂CMe₂Ph)₆, 1; Mo₂(CH₂SiMe₂Ph)₆, 2; W₂(CH₂SiMe₂Ph)₆, 3; and W₂(CH₂Ph)₆, 4] are reported. The synthetic effort suggests that ditungsten compounds are inherently more difficult to prepare and more thermally sensitive than dimolybdenum compounds, probably as a result of the larger dimetal core the ligands must protect. The structural data confirm that dimetal hexaalkyls exhibit shorter M≡M distances than do dimetal hexaalkoxides, even in a matched pair case where steric differences are minimal.     

“Aggregation-induced emission” of transition metal compounds: Design,mechanistic insights,and applications

In the last decades, compounds with ‘Aggregation-Induced Emission’ (AIE), which are weakly or non-emissive at all in solution but exhibit a strong luminescence in aggregated states, have emerged as an extraordinary breakthrough in the field of luminescent materials, allowing to circumvent ‘Aggregation Caused Quenching’ (ACQ), which in many cases prevents the development of efficient solid-state materials for optoelectronic applications.Since the discovery of AIE, many AIE-active materials have been developed, most of them composed of organic molecules, and thus fluorescent in nature. Although a wide range of applications such as bioimaging, sensing, multi-stimuli responsive materials, and optoelectronic devices have been proposed for this new class of materials, triplet harvesting phosphorescent materials have much longer lifetimes as compared to their singlet harvesting analogues, and for this particular reason, the development of AIE-active phosphorescent materials seems to be a promising strategy from the applications point of view. In this respect, the synthesis of new AIE-active systems including heavy metals that would facilitate the population of low-lying excited triplet states via spin-orbit coupling (SOC), for which the strength increases as the fourth power of atomic number, i.e. Z⁴, is highly desirable. This review covers the design and synthetic strategies used to obtain the AIEgens reported in the literature that contain either d-block metals such as Cu(I), Zn(II), Re(I), Ru(II), Pd(II), Ir(III), Pt(II), Au(I), and Os(IV), describing the mechanisms proposed to explain their AIE. New emerging high-tech applications such as OLEDs, chemical sensors or bioimaging probes proposed for these materials are also discussed in a separate section.     

Studies on coordination chemistry of a nitrogen–sulfur donor ligand with lighter and heavier metal ions and biological activities of its complexes

Complexes of S-benzyldithiocarbazate (SBDTC) with lighter and heavier metals, viz., Cr^III, Fe^III, Sb^III, Zr^IV, Th^IV and U^VI have been prepared and characterized by elemental analyses, conductivity measurements, and spectral studies. The complexes: [Cr(SBDTCA)₃],^** [Fe(SBDTCA)₃], [Sb(SBDTCA)₃], [Sb(SBDTCA)₂Cl · H₂O], [Zr(O)(SBDTCA)₂ · H₂O], [Th(SBDTCA)(NO₃)₃ · H₂O)], and [U(O)₂(SBDTCA)₂] were all prepared in alkaline media. They were all hexa-coordinated with bidentate, uninegative chelation of the ligand. [Fe(SBDTCA)₃], [Sb(SBDTCA)₃] and [Sb(SBDTCA)₂Cl · H₂O] were strongly effective against bacteria giving clear inhibition zones with Pseudomonas aeruginosa and Bacillus cereus. The compounds showed poor antifungal activity. The antimony complexes were strongly cytotoxic against leukemic cells with CD₅₀ values of 3.2–6.7 g cm^–3 as compared to the CD₅₀ value of 14.5 g cm^–3 of the free SbCl₃ molecule.     

“Matrix effects” in the activation of compounds with a system of conjugation in the inhibition of oxidative processes

Russian Chemical Bulletin -     

Molecular and electronic structures, Brönsted basicities, and Lewis acidities of group VIB transition metal oxide clusters

The structures and properties of transition metal oxide (TMO) clusters of the group VIB metals, (MO(3))(n) (M = Cr, Mo, W; n = 1-6), have been studied with density functional theory (DFT) methods. Geometry optimizations and frequency calculations were carried out at the local and nonlocal DFT levels with polarized valence double-zeta quality basis sets, and final energies were calculated at nonlocal DFT levels with polarized valence triple-zeta quality basis sets at the local and nonlocal DFT geometries. Effective core potentials were used to treat the transition metal atoms. Two types of clusters were investigated, the ring and the chain, with the ring being lower in energy. Large ring structures (n > 3) were shown to be fluxional in their out of plane deformations. Long chain structures (n > 3) of (CrO(3))(n) were predicted to be weakly bound complexes of the smaller clusters at the nonlocal DFT levels. For M(6)O(18), two additional isomers were also studied, the cage and the inverted cage. The relative stability of the different conformations of M(6)O(18) depends on the transition metal as well as the level of theory. Normalized and differential clustering energies of the ring structures were calculated and were shown to vary with respect to the cluster size. Br?nsted basicities and Lewis acidities based on a fluoride affinity scale were also calculated. The Br?nsted basicities as well as the Lewis acidities depend on the size of the cluster and the site to which the proton or the fluoride anion binds. These clusters are fairly weak Br?nsted bases with gas phase basicities comparable to those of H(2)O and NH(3). The clusters are, however, very strong Lewis acids and many of them are stronger than strong Lewis acids such as SbF(5). Br?nsted acidities of M(6)O(19)H(2) and M(6)O(18)FH were calculated for M = Mo and W and these compounds were shown to be very strong acids in the gas phase. The acid/base properties of these TMO clusters are expected to play important roles in their catalytic activities.     

Self-association in HOF and HNF2. Which atoms are the better proton acceptors,fluorine, oxygen or nitrogen?

The infrared and Raman spectra of solid HOF and HNF₂ are best interpreted in terms of hydrogen bridged aggregates involving the oxygen or nitrogen atoms, respectively, and not fluorine as proton acceptors. This results is contrary to intuition and the conclusions previously reached for solid HOF.     

Theoretical study of “sandwich” clusters of fused magnesium porphyrin oligomers with alkali metal atoms

The structural characteristics, energies, and spectroscopic properties of two-layer and multilayer “sandwich” clusters in which rings (layers) of fused porphyrin oligomers Mg₂P₂ and Mg₄P₄ (P = C₂₀H₁₂N₄) are separated by (Li) _n metal interlayers containing from 8 to 32 lithium atoms have been calculated by the density functional theory B3LYP method. The trends in the changes in these characteristics have been scrutinized as a function of the number of introduced Li atoms and the size and number of porphyrin layers. Calculations predict the high energetic stability and possibility of the existence of these sandwiches as paramagnetic clusters with mobile intercalated lithium ions. The latter, like intercalated graphite clusters, are expected to exhibit high electronic and ionic conductivity. The most favorable (with low or zero barriers) channels of migration of metal ions between the porphyrin layers are discussed.     

Syntheses,structures, and magnetism of two coordination compounds with 3,3′,4,4′-biphenyltetracarboxylic acid and 1,10-phenanthroline

Two coordination polymers, {[Mn(1,10-phen)₂(3,4-H₂bptc)]?·?(H₂O)}_{2 n} (1) and {[Co₂(1,10-phen)(3,4-bptc)(H₂O)₂]?·?H₂O} _n (2) (3,4-H₄bptc = 3,3′,4,4′-biphenyltetracarboxylic acid, 1,10-phen?=?1,10-phenanthroline), have been prepared and structurally characterized. In both compounds, 3,4-H₂bptc^2– and 3,4-bptc^4? exhibit different coordination modes and lead to various architectures. Compound 1 displays 1-D zigzag chains constructed with hydrogen bonds. Compound 2 exhibits a 2-D layer constructed from bpta^4? between the dinuclear Co(II) units. The thermal stabilities and magnetic properties are also reported. In addition, 1 was explored as a luminescent material. The carboxylic oxygen atoms act as H-bond acceptors and donors forming a 1-D ladder-like arrangement.     

Syntheses,crystal structures,and properties of two Cd–Fe heterobimetallic compounds with bridging en and dien ligands

From the system Cd(II)–L–[Fe(CN)₆]^4?, complexes [{Cd(en)}₂{Fe(CN)₆}] (1) and [{Cd(H₂O)(dien)}₂{Fe(CN)₆}] ? 4H₂O (2) were prepared and characterized. The same products were also isolated from mother liquors containing [Fe(CN)₆]^3? in which Fe(III) was reduced to Fe(II) upon irradiation. By the combination of IR and Mössbauer spectroscopy, the presence of the low-spin state (S = 0) for Fe(II) was corroborated in both 1 and 2. The Cd(II) and Fe(II) in both complexes are linked by bridging cyano ligands forming a 3-D crystal structure of 1 and a 1-D ribbon-like structural motif in 2. The bidentate en in 1 links two pentacoordinated Cd(II), while in 2 the dien ligand exhibits a rare chelating-bridging bonding mode completing the hexacoordination of Cd(II) and enhancing the dimensionality of the formed structure to 2-D. Fe(II) in both structures exhibits octahedral coordination by cyano bridging in 1 whereas in 2 two cyano ligands are terminal. Water of crystallization and the coordinated water in 2 are involved in hydrogen bonds. Dehydration in 2 is a one-step process with a minimum on the DTA curve at 92°C.     

Acidic-functionalized ionic liquid as an efficient, green and reusable catalyst for hetero-Michael addition of nitrogen, sulfur and oxygen nucleophiles to α,β-unsaturated ketones

A series of acidic-functionalized ionic liquids were synthesized and applied to the hetero-Michael addition of nitrogen, sulfur and oxygen nucleophiles to α,β-unsaturated ketones under solvent-free conditions. Notably, 1-methylimidazolium p-toluenesulfonic ([Hmim]OTs) was found to be the most efficient catalyst and could realize "homogeneous catalysis, two-phase separation". Additionally, the catalytic system has wide substrate scope and good to excellent yields (up to 99%) could be obtained at room temperature.     

Effects of metal ions and ligands on transesterification: synthesis,structures, and catalytic activities of a series of cation–anionic complexes with dipyridylamine ligands

A series of cation–anion complexes derived by 2,2′-dipyridylamine (Hdpa) and carboxylate ligands with formulas [Ni(Hdpa)₂(CH₃COO)]Cl(CH₃OH) (1), [Co(Hdpa)₂(CH₃COO)]Cl(CH₃OH) (2), [Ni(Hdpa)₂(CH₃CH₂CH₂COO)]Cl (3), [Co(Hdpa)₂(CH₃CH₂CH₂COO)]Cl (4), [Ni(Hdpa)₂(C₆H₅COO)]Cl (5), and [Co(Hdpa)₂(C₆H₅COO)]Cl (6), were synthesized and characterized by IR, elemental analysis, MS(ESI), TG analysis, UV-Vis, and fluorescence spectra. X-ray single crystal structural analysis showed that the coordination geometries of metal ions in these complexes are similar and they are cation–anion species. The hydrogen-bonding structures are 1-D chains through the N–H···Cl bonds. There are weak stacking interactions between pyridine rings in 1–4, while there are no stacking interactions in 5 and 6. We have investigated the transesterification of phenyl acetate with methanol catalyzed by 1–6 under mild conditions; 1–4 are homogeneous catalysts while 5 and 6 are heterogeneous catalysts due to their poor solubility in methanol. Cobalt complexes exhibit higher catalytic activities than corresponding nickel complexes. Complex 4 is the best catalyst of these six complexes.     

Investigation of the charge state of heteroatoms in organic compounds of third-row elements by x-ray fluorescence spectroscopy 10. Correlations between values of the shifts of the kα lines of sulfur,phosphorus, and chlorine and the values of the effective charges of these atoms determined from semiempirical quantum-chemical calculations

A set of correlation equations which relate the experimental values of the shifts of the E K lines (E=S, P, Cl) for various classes of E-containing compounds to the values of the effective charges of the atoms of E determined from quantum-chemical calculations by the CNDO/S, CNDO/2, INDO, MINDO/3, and MNDO methods in the minimal basis and the CNDO/S method in an expanded basis has been obtained. It has been established that the INDO method in the minimal basis is best for calibrating the values of (E K) on the basis of the values of the effective charges of the atoms, while the CNDO/2 method and the INDO in the expanded basis are practically unsuitable for determining the values of the effective charges of S and P atoms.For previous communication, see [1].Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 403–410, February, 1991.     

Syntheses,crystal structures,and characterization of three metal–organic complexes with 2,2′-biphenyldicarboxylic acid and phenanthroline ligands

Three complexes constructed with 2,2′-biphenyldicarboxylic acid, multidentate nitrogen donors, and metal salts, {[Cd(2,2′-dpdc)(tppp)(H₂O)]₂?·?2H₂O} _n (1), {[Pb(2,2′-dpdc)(pyphen)]₂} _n (2), and {[Pb(2,2′-dpdc)(dppz)]} _n (3) (H₂dpdc = 2,2′-diphenyldicarboxylic acid; tppp = 4-(1H-1,3,7,8-tetraazacyclopenta[l]phenanthren-2-yl)phenol; pyphen?=?pyrazino[2,3-f]-[1,10]phenanthroline; and dppz = dipyrido[3,2-a:2′,3′-c]phenazine), are synthesized under hydrothermal conditions. These complexes are characterized by single-crystal X-ray diffraction, elemental analysis, IR, TGA, and photoluminescence. In 1, two 2,2′-dpdc ions bridge two Cd(II) ions to form an isolated cluster with Cd?···?Cd distance of 5.023(4)?Å. These clusters are further linked by intermolecular hydrogen bonds, yielding a 2-D supramolecular structure. Complex 2 contains two crystallographically independent Pb(II) ions in the asymmetric unit. Pb1 ions are bridged by 2,2′-dpdc anions to form a chain along the x-axis. Two Pb2 ions are coordinated by two 2,2′-dpdc anions and two pyphen ligands to form a cluster. These clusters are linked by π–π interactions to yield a 1-D supramolecular chain along the y-axis. In 3, neighboring Pb(II) atoms are bridged by 2,2′-dpdc anions to form a 1-D chain structure. Further, the chains are linked into a 3-D supramolecular network through aromatic π–π interactions.     

Syntheses,crystal structures,and optical properties of a series of transition metal coordination polymers with chelidamic acid and 4,4′-bipyridine

A series of transition metal (Zn, Cu, Mn) complexes with chelidamic acid (2,6-dicarboxy-4-hydroxypyridine, H₃CAM) and 4,4′-bipyridine (bipy), [Zn₂(bipy)Cl₂] _n (1), {[Zn₂(HCAM)(H₂CAM)₂]?·?(bipy)?·?3.5H₂O} _n (2), [Mn₃(HCAM)₃(H₂O)₇]?·?(bipy)?·?3H₂O (3), [Mn₂(HCAM)₂(bipy)?·?(H₂O)₂]?·?4H₂O (4), [Cu₂(HCAM)₂(bipy)?·?(H₂O)₂]?·?4H₂O (5), and Cu₂(HCAM)₂(bipy)?·?(H₂O)₂ (6), have been synthesized by hydrothermal or solution methods and characterized by single-crystal X-ray diffraction. The structural analyses reveal that 1 exhibits a zigzag chain of Zn(II), Cl^?, and 4,4′-bipyridine. In 2, a 1-D polymeric [Zn₂(HCAM)(H₂CAM)₂] _n chain and a discrete 4,4′-bipyridine assemble into a 2-D supramolecular network via H-bonds. Complex 3 consists of asymmetric units of Mn₃(HCAM)₃(H₂O)₇ that are linked by hydrogen bonds to form a 2-D H-bonded network. Complexes 4–6 are isomorphous and possess discrete structures. The photoluminescent properties of 1–6 at room temperature were studied.