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Rh-catalyzed C-H insertion reactions to form β-lactones suffer from post-transition state bifurcations, with the same transition states leading to ketones and ketenes via fragmentation in addition to β-lactones. In such a circumstance, traditional transition state theory cannot predict product selectivity, so we employed

Sb(V) in strong Bronsted acid solvents is traditionally assumed to react with light alkanes through superacid protonolysis, which results in carbocation intermediates, H2, and carbon oligomerization. In contrast to this general assumption, our density functional theory (DFT) calculations revealed an accessible barrier for C-H activation between methane and Sb(V) in sulfuric acid that could potentially outcompete superacid protonolysis. This prompted us to experimentally examine this reaction in sulfuric acid with oleum, which has never been reported because of presumed superacid reactivity. Reaction of methane at 180 °C for 3 h resulted in very high yields of methyl bisulfate without significant overoxidation. Our DFT calculations show that a C-H activation and Sb-Me bond functionalization mechanism to give methyl bisulfate outcompetes methane protonolysis and many other possible reaction mechanisms, such as electron transfer, proton-coupled electron transfer, and hydride abstraction. Our DFT calculations also explain experimental hydrogen-deuterium exchange studies and the absence of methane carbo-functionalization/oligomerization products. Overall, this work demonstrates that in very strong Bronsted acid solvent, Sb(V) can induce innersphere reaction mechanisms akin to transition metals and outcompete superacid reactivity.

Quantum–mechanical transition states can aid in the identification of promising catalysts for methane C–H activation and functionalization. However, only a limited amount of the vast metal–ligand chemical space has been computationally evaluated. To begin to solve this problem, we showcase a workflow that combines automated construction of Pt(II)-ligand combinations and automated transition-state searching with machine learning to maximize the generation of fully optimized transition states.

This study was conducted to reveal the effects of silicon (Si) application on nutrient utilization efficiency by rice and on soil nutrient availability and soil microorganisms in a hybrid rice double-cropping planting system. A series of field experiments were conducted during 2017 and 2018. The results showed that Si nutrient supply improved grain yield and the utilization rates of nitrogen (N) and phosphorus (P) to an appropriate level for both early and late plantings, reaching a maximum at 23.4 kg/ha Si. The same trends were found for the ratios of available N (AN) to total N (TN) and available P (AP) to total P (TP), the soil microbial biomass carbon (MBC), microbial biomass nitrogen (MBN), microbial biomass phosphorus (MBP), and the ratios of MBN to TN and MBP to TP, at different levels of Si. Statistical analysis further revealed that Si application enhanced rice growth and increased the utilization rate of fertilizer due to an ecological mechanism, i.e., Si supply significantly increased the total amount of soil microorganisms in paddy soil compared to the control. This promoted the mineralization of soil nutrients and improved the availability and reserves of easily mineralized organic nutrients.

Branched selectivity in asymmetric allylic C-H alkylation is enabled by using 2-acylimidazoles as nucleophiles in the presence of a chiral phosphoramidite-palladium catalyst. A wide range of terminal alkenes, including 1,4-dienes and allylarenes, are nicely tolerated and provide chiral 2-acylimidazoles in moderate to high yields and with high levels of regio-, and enantio-, and E/Z-selectivities. Mechanistic studies using density-functional theory calculations suggest a nucleophile-coordination-enabled inner-sphere attack mode for the enantioselective carbon-carbon bond-forming event.

Herein, we describe an example of catalytic asymmetric synthesis of sulfinamides. Aromatic sulfenamides were chosen as useful substrates, because of the indispensable N–H bond, which could form an efficient hydrogen bond with chiral phosphoric acid. H2O2 (35%) was used as the terminal oxidant for preparation of sulfinamides in high yields and enantioselectivities, which could be easily derivatized to sulfoxides and other sulfinamides without loss of the enantioselectivity.

Amine/Pd(II) cooperative catalysis has enabled a highly enantioselective addition of cyclic ketones to unactivated alkenes. The hallmark of the strategy includes amide-directed, regioselective activation of alkenes by Pd(II) and enhancing the nucleophilicity of α-carbon of the ketones by enamine catalysis to synergistically drive the reaction, which is basically unable to be accessed by a single catalyst. The combination of a commercially available Pd(II) catalyst and diphenylprolinol was able to provide the γ-addition products with good to high yields and efficient stereochemical control (up to 95% ee).

Acyclic internal alkenes are a class of challenging substrates in asymmetric Heck-type reactions due to difficulties related to both reactivity and selectivity control. Employing acyclic alkenyl alcohols, an asymmetric Heck-Matsuda reaction is developed through the strategy of chiral anion phase transfer. Various chiral ketones could be obtained in high levels of enantioselectivity. A catalytic amount of dimethyl sulfoxide (DMSO) as an additive is crucial for the reaction to suppress the palladium-hydride-mediated side reactions.

Ab initio molecular dynamics calculations were used to explore the underlying factors that modulate the velocity of hydrogen migration for 1,2 hydrogen shifts in carbocations in which different groups interact noncovalently with the migrating hydrogen. Our results indicate that stronger electrostatic interactions between the migrating hydrogen and nearby π-systems lead to slower hydrogen migration, an effect tied to entropic contributions from the hydrogen + neighboring group substructures.

To determine whether the newly built lead-acid battery agglomeration area in a town in northern Zhejiang had an impact on the surrounding soil environment after seven years of operation, 76 samples of surface soil around the lead-acid battery concentration area were collected, and the contents of Hg, As, Cu, Zn, Pb, Cd, Ni, and Cr in the soil were determined. Based on the spatial distance of the agglomeration area and 50, 450, and 850 m from the agglomeration area boundary, the soil environmental quality was evaluated using the single factor index, Nemerow comprehensive pollution index, and potential ecological risk index methods. The spatial distribution characteristics of the heavy metals were analyzed using the geostatistical method, and the sources of heavy metals affecting the soil environment were determined by correlation analysis. The results showed that the average contents of Hg, Zn, and Pb in eight heavy metals were higher than their corresponding background values at all spatial scales. The average Cd content in spatial scales other than the agglomeration area was larger than its background value. Only As at 50 m was greater than its background value, whereas the average content of other elements at all spatial distances was lower than their corresponding background values. The spatial variability was high for Hg and Cd but not obvious for other elements. This implies that the influence of regional activities was concentrated mainly on Hg and Cd; the content of both increased with distance from the agglomeration area. Hg and Cd exceeded the risk screening values and were distributed mainly at 450 m and 850 m; 33.33% and 38.89% Hg points and 27.78% and 55.56% Cd points were observed at these distances, respectively. The spatial distribution characteristics of Hg and Cd were consistent with their contents; only Zn and Pb had scattered points that exceeded the risk screening values and generally no obvious spatial distribution characteristics. According to the risk analysis of soil comprehensive pollution caused by the eight heavy metals, Cd was the main source of soil comprehensive pollution risk at a contribution rate of 36.73%, which caused the soil at 850 m to be in a state of alert. Soil ecological risk at a medium level occurred mainly at 450 m and 850 m outside the agglomeration area from Hg and Cd. The contribution rates to the soil quality at these distances were 46.30% and 39.37% for Hg and 38.98% and 49.30% for Cd, respectively. This indicates that regional activities caused Hg and Cd to be the main elements affecting soil quality in the study area. The results of geostatistics and multivariate statistical analysis showed that Hg and Cd were diffused inward from the periphery of the agglomeration area on the axis of the local main wind direction (northeast-southwest), and the main sources of both were coal-burning activities of enterprises in the periphery of the agglomeration area. In summary, the newly build lead-acid battery agglomeration area has not significantly affected the accumulation of heavy metals in the agglomeration area and in the surrounding soil after seven years of operation.

A palladium(II)-catalyzed asymmetric 1,2-diamination of 1,3-dienes with readily available dialkylureas was established by using a chiral pyridine-oxazoline ligand. The diamination reaction exclusively occurs at the terminal C-C double bond of the 1,3-dienes to give 4-vinylimidazolidin-2-ones in high yields and with excellent levels of enantioselectivity (up to 99% yield, 97% ee). The reaction could feasibly be applied for gram-scale synthesis with a 1:1 ratio of the diene and the urea.

An enantioselective α-amination of esters by a Lewis base/copper(I) cooperative catalysis strategy has been developed. The transient chiral C1-ammonium enolate generated from pentafluorophenyl ester and nucleophilic Lewis base is nicely compatible with the copper intermediate formed from N, N-di- t-butyldiaziridinone and Cu(I) to allow for high levels of stereochemical control. The cooperative catalytic reaction leads to a diverse set of highly enantioenriched hydantoins in good yields with excellent enantioselectivities (90-99% ee).

A chiral PdII -catalyzed cascade sp2 C-H functionalization/intramolecular asymmetric allylation reaction is reported. A new chiral sulfoxide-oxazoline (SOX) ligand bearing single chiral center on the sulfur was identified as the optimal ligand for the reaction, being efficient both in the C-H cleavage step and the stereocontrol of the allylation step. The broad scope of this method with respect to aryl ureas and 1,3-dienes enables the rapid construction of valuable chiral indoline derivatives with high yields and enantioselectivities (up to 99 % yield, up to 95:5 e.r.).

A palladium-catalyzed enantioselective carboannulation of 1,3-dienes and aryl iodides has been established by using a BINOL-based phosphoramidite ligand. This reaction proceeded via a tandem Heck-type insertion and asymmetric intramolecular Tsuji–Trost allylic alkylation, providing indane derivatives with high levels of enantioselectivity (up to >99% ee).

An asymmetric dehydrogenative Diels–Alder reaction of 2-methyl-3-phenylmethylindoles and α,β-unsaturated aldehydes has been established. The successful in situ generation of the indole ortho-quinodimethane intermediate and the iminium activation of enals are the keys to success, providing various tetrahydrocarbazole derivatives with up to >99% ee.

A [4+2] cycloaddition reaction proceeding through tandem cross-dehydrogenative coupling/intramolecular hydroarylation between N-aryltetrahydroisoquinolines and crotonaldehyde was developed by virtue of enamine–iminium catalysis, which enabled the rapid construction of ring-fused tetrahydroquinolines. The first metal-free catalytic oxidative coupling of γ-selective C(sp3)–H bonds of crotonaldehyde was realized by using a secondary amine catalyst and 2,3-dichloro-5,6-dicyanoquinone.

A [1,5]-hydride shift of sp(3) C-H onto an unactivated carbon-carbon triple bond catalyzed by a gold(I) complex enabled N-propargylisoindolines to be latent dienes and therefore triggered an intermolecular Diels-Alder reaction with dienophiles. This protocol provides an atom-economical and straightforward approach to access a wide range of polycyclic skeletons in high yields and with excellent diastereoselectivities from easily accessible molecules.

An efficient strategy for the enantioselective construction of [6,5,6]-carbocyclic compounds has been established via one-pot reaction of (E)-4-(2-ethynylphenyl)but-3-en-2-ones with maleimide sequentially catalyzed by cinchona alkaloid-based primary amine and gold complex (Ph3PAuNTf2). This methodology provided a facile approach to access the [6,5,6]-tricyclic skeleton in fairly good yield and with perfect enantioselectivities (98% to >99% ee).

In order to obtain the porous silicon, amorphous silica was prepared from serpentine by leaching experiment The XRF results shows that the leach residues almost compose of amorphous silica, the content is 92.37%, via magnesiothermic reduction, The XRD results shows the amorphous silica was reduced to porous crystal silicon successfully and The SEM results shows they have similar morphology. One of the most important properties of porous silicon was characterized by PL and with an excitation at 365 nm. an emission centered in the blue region.

The effects of calcium hexaluminate addition on the microstructure and mechanical properties of zirconia-toughened-alumina ceramic were investigated. Zirconia-toughened-alumina (ZTA) composite ceramics which have different additions of calcium hexaluminate were successfully fabricated by pressureless sintering at 1600°C for 3h. The result shows that the bending strength and abrasive wearing improved with the increasing of CaAl12O19addition while the fracture toughness declined.

The first enantioselective heteroannulation of 1,3-dienes by 2-iodoanilines and 2-iodobenzylic alcohols is described. The application of a BINOL-derived phosphoramidite ligand bearing electron-withdrawing substituents is the key to obtaining high enantioselectivity. This protocol provides an efficient way to access optically active chiral indolines and isochromans from readily available starting materials.

The unusual and strong cation–π interactions are found between cations (H+, Li+, Na+, Be2+, and Mg2+) and the electron-deficient B B bond using MP2(full) and CCSD(T) methods at 6-311+G(2df) (6-311++G(2df,2p) for H+ complexes) and aug-cc-pVTZ levels, accompanied by the B B bond contraction. A comparison with those between the corresponding cations and HC CH are also carried out. The binding energies follow the order of OCB BCO⋯H+ ≈ OCB BCO⋯Be2+ > OCB BCO⋯Mg2+ >> OCB BCO⋯Li+ > OCB BCO⋯Na+ and OCB BCO⋯cations > HC CH⋯cations at four levels. The atoms in molecules (AIM) theory has been applied to convince covalent interaction in the H+ complexes and confirm that the electron-deficient B B triple bond can be as the strong π-electron donor in the cation–π interaction. The analyses of natural bond orbital (NBO) and electron density shifts have revealed the nature of the cation–π interaction and explained the origin of B B bond contraction.

Characteristics of mineral elements in plants are often strongly influenced by species' abundance and heterogeneous habitats. Therefore, nutrient analysis, after excluding interference of habitat heterogeneity, would directly reflect genetic traits of species in the community. From another aspect, knowledge of responses of species to environmental variation would be helpful in the management of natural and man-made ecosystems, especially those containing rare and endangered plants conserved in gardens. We studied the characteristics of twelve nutrient elements in 90 species in Wuhan Botanical Garden (WBG) and provided explanations of their survival status. Concentrations of the 12 nutrients in the artificial garden were consistent with those in other natural communities in the subtropical zone of China. Features of nutrient-limited at the community level were also consistent with the regional characteristics (N:P ratio being 9.79 ± 3.22, as exhibiting N-limited). The Ca + Mg concentrations differ...

The nature of the unusual cation-pi interactions between cations (H(+), Li(+), Na(+), Be(2+) and Mg(2+)) and the electron-deficient B=B bond of the triplet state HB=BH (3 Sigma g-) was investigated using UMP2(full) and UB3LYP methods at 6-311++G(2df,2p) and aug-cc-pVTZ levels, accompanied by a comparison with 1:1 and 2:1 sigma-binding complexes between BH and the cations. The binding energies follow the order HB=BH...H(+) > HB=BH...Be(2+) > HB=BH...Mg(2+) >> HB=BH...Li(+) > HB=BH...Na(+) and HB=BH ((1)Delta(g))...M(+)/M(2+) > H(2)C=CH(2)...M(+)/M(2+) > HC identical with CH...M(+)/M(2+) > HB=BH (3 Sigma g-)...M(+)/M(2+). Furthermore, except for HB...H(+), the sigma-binding interaction energy of the 1:1 complex HB...M(+)/M(2+) is stronger than the cation-pi interaction energy of the C(2)H(2)...M(+)/M(2+), C(2)H(4)...M(+)/M(2+), B(2)H(2) ((1)Delta(g))...M(+)/M(2+) or B(2)H(2) (3 Sigma g-)...M(+)/M(2+) complex, and, for the 2:1 sigma-binding complexes, except for HBBe(2+)...BH, they are less stable than the cation-pi complexes of B(2)H(2) ((1)Delta(g)) or B(2)H(2) (3 Sigma g-). The atoms in molecules (AIM) theory was also applied to verify covalent interactions in the H(+) complexes and confirm that HB=BH (3 Sigma 3-) can be a weaker pi-electron donor than HB=BH ((1)Delta(g)), H(2)C=CH(2) or HC identical with CH in the cation-pi interaction. Analyses of natural bond orbital (NBO) and electron density shifts revealed that the origin of the cation-pi interaction is mainly that many of the lost densities from the pi-orbital of B=B and CC multiple bonds are shifted toward the cations.

The unusual T-shaped X H…π hydrogen bonds between HF and BB or CC multiple bonds are compared using the (U)MP2 and DFT ((U)B3LYP functional) methods with the 6-311++G(2df,2p) and aug-cc-pVTZ basis sets. The binding energies follow the order of HB BH (1Δg)…HF > H2C CH2…HF > HC CH…HF > OCB BCO…HF > HB BH ( 3 Σ g - )…HF. NBO analysis and the results of the AIM charge density and electron density shifts confirm that, although BB multiple bonds are more electron-deficient than CC multiple bonds, HB BH (1Δg) can be as the stronger T-shaped X H…π hydrogen-bond proton acceptor than the CC multiple-bond monomers.

The unusual weak T-shaped X H…π hydrogen bonds are found between the B B double bond of the triplet state HB BH ( 3 Σ g - ) and the acid hydrogen of HF, HCl, HCN and H2C2 using UMP2 and UB3LYP methods at 6-311++G(2df,2p) and aug-cc-pVTZ levels. The binding energies follow the order of HB BH…HF > HB BH…HCl > HB BH…HCN > HB BH…H2C2, and the hydrogen-bonded interactions in the triplet state complexes HB BH…HX (3B1) are found to be weaker than those in HC CH…HX and OCB BCO…HX. The analyses of natural bond orbital (NBO) and the electron density shifts reveal that the nature of the T-shaped X H…π hydrogen-bonded interaction is that the lost density from the π-orbital of B B bond is shifted toward the hydrogen atom of HX, leading to the electron density accumulation and the formation of the hydrogen bond. The atoms in molecules (AIM) theory has been also applied to characterize bond critical points and confirm that it is difficult for the ground electronic state of HB BH to be as the hydrogen-bond proton acceptor, perhaps due to the nature of electron-deficient B B double bond.

This paper reviewed a large scale conservation work of rare and endangered plants currently conducted in main botanical gardens in China, and the existed, predictable and neglected problems on plant growth and reproduction in ex-situ conservation process. Considered the status quo in plant ex conservation, a nutritional strategy on the plant conservation was proposed based on ‘Ecological Similarity’. Its main idea was that the ex-situ conservation plants coming from natural ecosystem were compulsively allocated in the agro-ecosystems and would return to natural ecosystem ultimately. Therefore, research on plant nutrition of the ex-situ conservation plants should neither just pursue yield and quality as that in agro-ecosystems nor merely stay on intrinsic natures without human intervening. We should give attentions to both of their attributes as in natural ecosystems and in agro-ecosystems, i.e., taking full advantage of plant nutritional measures as in agro-ecosystems to solve actual survival problems of the ex-conservation plants, and ensuring the final goal of returning to nature and playing its ecological role.

The unusual T-shaped X–H···π hydrogen bonds are found between the B B triple bond and the acid hydrogen of HF, HCl, HCN and H 2 C 2 using ab initio method at 6-311++G(2d,p) and aug-cc-pVTZ levels, accompanied by the B B bond contraction. The binding energies follow the order of OCB BCO···HF > OCB BCO···HCl > OCB BCO···HCN > OCB BCO···H 2 C 2 . The analyses of the charge density and electron density shifts explain the origin of the B B bond contraction and confirm that the B B triple bond can be as potential proton acceptor.

The four types of unusual T-shaped X–H…π hydrogen bonds, which are O–H…C N, O–H…N C, N–H…C N and C–H…N C, are found using B3LYP and MP2 methods at 6-311++G(2df, 2p) and aug-cc-pVTZ levels in CH 3 C N…H 2 O, CH 3 N C…H 2 O, CH 3 C N…H 3 N and CH 3 N C…H 2 C 2 complexes. In the CH 3 C N…H 2 O and CH 3 N C…H 2 O, the –C N or –N C triple bond offers the p 1.00 -hybridization π-electrons of the carbon and nitrogen atoms to the contacting σ ( O H ) ∗ antibonding orbital of the H 2 O, apart from the interaction formed by which the oxygen offers its lone pair electrons to the σ ( C H ) ∗ antibonding orbital of the methyl group. These two complexes are comparatively stable, in which the CH 3 C N…H 2 O is the most stable one because of the strongest intermolecular interaction coming from O–H…C N hydrogen bond. In the CH 3 C N…H 3 N and CH 3 N C…H 2 C 2 complexes, the –C N or –N C triple bond offers the pure p electrons of π orbital to the σ N H ) ∗ or σ C H ) ∗ antibonding orbital of the H 3 N or H 2 C 2 , and the intermolecular hydrogen-bonded interactions in these two complexes are weak. For the T-shaped X–H…π (X = O, N, C) hydrogen bonds, the ZPE correction for binding energies is very necessary for B3LYP and MP2 methods at 6-311++G(2df, 2p) and aug-cc-pVTZ levels. The net charge transfer is from carbon to nitrogen atom after complexation for the –C N group while reversely for –N C, and the former becomes more polarized and the latter favors weaker.

Molecular dynamics (MD) methods were employed to study the binding energies and mechanical properties of selected crystal planes of 1,3,5,7-tetranitro-1,3,5,7-tetrazacyclooctane (HMX)/nitroguanidine (NQ) cocrystals at different molecular molar ratios. The densities and detonation velocities of the cocrystals at different molar ratios were estimated. The intermolecular interaction and bond dissociation energy (BDE) of the N-NO2 bond in the HMX:NQ (1:1) complex were calculated using the B3LYP, MP2(full) and M06-2X methods with the 6-311++G(d,p) and 6-311++G(2df,2p) basis sets. The results indicated that the HMX/NQ cocrystal prefers cocrystalizing in a 1:1 molar ratio, and the cocrystallization is dominated by the (0 2 0) and (1 0 0) facets. The K, G, and E values of the ratio of 1:1 are smaller than those of the other ratios, and the 1:1 cocrystal has the best ductility. The N-NO2 bond becomes stronger upon the formation of the intermolecular H-bonding interaction and the sensitivity of HMX decreases in the cocrystal. This sensitivity change in the HMX/NQ cocrystal originates not only from the formation of the intermolecular interaction but also from the increment of the BDE of N-NO2 bond in comparison with isolated HMX. The HMX/NQ (1:1) cocrystal exhibits good detonation performance. Reduced density gradient (RDG) reveals the nature of cocrystallization. Analysis of the surface electrostatic potential further confirmed that the sensitivity decreases in complex (or cocrystal) in comparison with that in isolated HMX.

A [4+2] cycloaddition reaction proceeding through tandem cross-dehydrogenative coupling/intramolecular hydroarylation between N-aryltetrahydroisoquinolines and crotonaldehyde was developed by virtue of enamine–iminium catalysis, which enabled the rapid construction of ring-fused tetrahydroquinolines. The first metal-free catalytic oxidative coupling of γ-selective C(sp3)–H bonds of crotonaldehyde was realized by using a secondary amine catalyst and 2,3-dichloro-5,6-dicyanoquinone.

A [1,5]-hydride shift of sp3 C–H onto an unactivated carbon–carbon triple bond catalyzed by a gold(I) complex enabled N-propargylisoindolines to be latent dienes and therefore triggered an intermolecular Diels–Alder reaction with dienophiles. This protocol provides an atom-economical and straightforward approach to access a wide range of polycyclic skeletons in high yields and with excellent diastereoselectivities from easily accessible molecules.

The thermodynamic properties of system (HCl + NaCl + C6H12O6 + H2O) were studied by e.m.f. measurement in the cells without liquid junction: (A) Pt , H 2 ( p = 101.325 kPa ) | HCl ( 0.01000 mol · kg - 1 ) | AgCl – Ag (B) Pt , H 2 ( p = 101.325 kPa ) | HCl ( m ) , C 6 H 12 O 6 ( w ) , H 2 O ( 1 - w ) | AgCl – Ag (C) Pt , H 2 ( p = 101.325 kPa ) | HCl ( m A ) , NaCl ( m B ) , C 6 H 12 O 6 ( w ) , H 2 O ( 1 - w ) | AgCl – Ag At constant total ionic strength (0.5, 1.0, 1.5, and 2.0) mol · kg−1, from (5 to 45) °C, where mA and mB are the molalities of HCl and NaCl, respectively, and w is the mass fraction of fructose in the mixed solvent, which is w = 0.1 during all the measurements. The standard electrode potential of Ag | AgCl in the pure water and mixed solvent has been determined from cells (A) , (B) . The activity coefficients lg γA of HCl in the mixed solvent system have been determined from cell (C) .The results show that the activity coefficients of HCl in (HCl + NaCl) solutions still obey Harned’s Rule. The standard transfer Gibbs free energies, entropy and enthalpy of HCl have been calculated. The primary, secondary and total medium effect of HCl have been calculated and discussed.

The successful construction of [6,5,6]-carbocyclic compounds is established via one-pot reaction of (E)-(ethynylphenyl)butenones with maleimide sequentially catalyzed by cinchona alkaloid-based primary amine CIN and a gold complex.

The additive reactivity of 2,6,8,12-tetraacetyl-4, 10-dibenzyl-2,4,6,8,10,12-hexazatetracyclo [5.5.0.05.9. 03.11] dodecane (3) in several conditions was studied. It was found that the N-benzyl groups in compound 3 could be oxidized to benzoyl groups by Cr(VI) reagents, and could be removed by cerium ammonium nitrate (CAN), meanwhile nitroamine products were given.

Oxidation of hexabenzylhexaazaisowurtzitane by different Cr(VI) reagents has been studied, and a very stable amide product, hexabenzoylhexaazaisowurtzitane, has been obtained.

The crystal and molecular structure of an interesting cage compound is described. Crystal data: C48H36N6O6·(CH3)2CO; monoclinic; space group: P21/n; a = 14.948(3) A, b = 15.079(3) A, c = 19.539(4)A, β = 93.93(3)°, V = 4394(2)A3; and Z = 4.

The DFT-B3LYP and MP2 methods with 6-311G** and 6-311++G** basis sets have been applied to study the complexation energies of the host-guest complexes between the cone calix[4]arene and Li(+) or Na(+) on the B3LYP optimized geometries. A comparison of the complexation energies obtained from the MP2(full) with those from MP2(fc) method is also carried out. The result shows that it is essential to introduce the diffuse basis set into the geometry optimizations and complexation energy calculations of the alkali-metal cation-pi interaction complexes of calix[4]arene, and the D (e) values show a maximum of 21.13 kJ mol(-1) (14.45% of relative error) between the MP2(full)/6-311++G** and MP2(fc)/6-311++G** method. For Li(+) cation, the complexation is mainly energetically stabilized by the lower rim/cation (namely O-Li(+)) interaction. However, binding energies and NBO analyses confirm that Na(+) cation prefers to enter the calix[4]arene cavity and the cation-pi interaction is predominant, which contradicts the previous low-level theoretical studies. Furthermore, the complexation with Li(+) is preferred over that with Na(+) by at least 12.70 kJ mol(-1) at MP2(full)/6-311++G**//B3LYP/6-311++G** level.