C-ring Research Articles

Novel alginates prepared by independent control of chain stiffness and distribution of G-residues: Structure and gelling properties

The study of alginate hydrogels is of increasing interest, given their potential applications as biomaterials for tissue engineering and for encapsulating drugs and living cells. In this study, we present a new strategy for tailoring alginates on the basis of homopolymeric mannuronan, where the chain stiffness and the content of G-residues could be varied independently. Partial periodate oxidation (0–8%) followed by borohydride reduction, introducing flexible linkages through C2–C3 cleavage and ring opening, was combined with in vitro epimerization, introducing either alternating (MG) sequences (in the case of enzyme AlgE4) or G-blocks (in the case of enzyme AlgE6). Both enzymes are recombinantly expressed from Azotobacter vinelandii. Two strategies were followed: (a) oxidation/reduction followed by epimerization (b) epimerization to 90% G followed by oxidation/reduction. The resulting alginates were characterised by NMR spectroscopy and size-exclusion chromatography (SEC) with multi angular laser light scattering (MALLS) and viscosity detectors. Gels were prepared using the ‘internal setting’ method with either 10 mM or 20 mM Ca 2+ present, and studied by small-strain oscillatory measurements. It was found that periodate oxidation, in the range P 0 = 0.02–0.06, had a pronounced influence on the gelling properties. The decrease in dynamic storage modulus ( G′) could mainly be attributed to increased local flexibility and not only a decrease in G-block lengths as a consequence of oxidation. The new alginate gels are easily degradable in a mild acidic environment and the degradation is easier to control than gels made of unoxidized alginate.

5-{[(3R,5aS,6R,8aS,9R,10S,12R,12aR)-3,6,9-Trimethylperhydro-3,12-epoxy-1,2-dioxepino[4,3-i]isochromen-10-yl]oxymethyl}benzene-1,3-diol

The title compound, C22H30O7, is a fused five-ring system that is of inter­est for its anti­cancer and anti­malarial activity. The six-membered C6 and C5O rings display chair conformations. The six-membered C3O3 ring containing the ether and per­oxy functionalities has a distorted boat conformation, with a C—O—O—C torsion angle of 42.6 (1)° for the per­oxy group. The seven-membered C6O ring has a distorted boat-type conformation, while the seven-membered C5O2 ring has a very distorted chair-type conformation. The structure contains inter­molecular O—H⋯O and O—H⋯(O,O) bonds that link the mol­ecules into sheets parallel to the (100) planes.

Ethyl 5-amino-1-(4-chloro-2-nitrophenyl)-1H-pyrazole-4-carboxylate

In the mol­ecule of the title compound, C12H11ClN4O4, the pyrazole ring is coplanar with the amino and ethoxy­carbonyl groups within 0.026 (2) and 0.105 (2) Å, respectively. The C 6 ring of the 4-chloro-2-nitro­phenyl group is twisted by 53.58 (4)° relative to the plane of the pyrazole ring. The planar structure of the pyrazole ring is stabilized by an intra­molecular N—H⋯O hydrogen bond between its substituents. Neighbouring mol­ecules are linked through inter­molecular N—H⋯N and N—H⋯O hydrogen bonds, giving rise to one-dimensional tapes along the b axis. Mol­ecules in the chain are linked to those of an adjacent chain through weak C—H⋯O inter­actions, forming a three-dimensional network.

Isoflavone Daidzein: Chemistry and Bacterial Metabolism

Isoflavone daidzein is a phytoestrogen widely distributed in Leguminosae and is especially rich in the soybean. The C6-C3 (rings B and C) unit of isoflavones is derived from the phenylpropanoid pathway and the remaining C6 (ring A) unit is from the polyketide pathway. This unique carbon skeleton is the result of isomerization of the flavone catalyzed by the isoflavone synthase, a cytochrome P450 enzyme. The isoflavones daidzein and genistein are present in the plant mostly in the glucosylated forms. However, in the human intestine, the glycosidic linkage is broken, and the free form is uptaked into blood stream. The free form is further metabolized into various reduction products to end up at the equol, which is known to have the most potent estrogenic effect among the metabolites. Several human intestinal bacteria that can convert daidzein into equol have been described, and the study into the chemistry and biochemistry of the daizein reduction would be rewarding to the improvement of the human health.

Cyclopentadiene combustion in a plug flow reactor near 1150 K

Cyclopentadienyl (CPDyl) was generated for study by oxidizing and pyrolizing 1,3-cyclopentadiene (CPD) in Princeton’s adiabatic, atmospheric pressure flow reactor. This study used nitrogen carrier gas, initial CPD concentrations from 1000 to 3000ppm by volume (ppmv), equivalence ratios from fuel lean (ϕ=0.6) to pyrolytic conditions (ϕ=100) and initial temperatures from 1100 to 1200K. The reaction progress was followed from 5 to 150ms using a water cooled sample probe and GC–FID analysis of C1–C14 species. The oxidation results show that CPD and CPDyl react via 19 pathways to yield 22 hydrocarbon intermediates. Analysis of the oxidative CPDyl ring opening pathways reveals the importance of the 2,4-cyclopentadienoxy (c-C5H5O) β-scission reaction: c-C5H5O↔CHCH–CHCH–CHO. The fastest theoretical mechanism has a calculated unimolecular high-pressure rate constant of 2.00×1013e−7215/Ts−1 which is seven orders of magnitude larger at 1150K than the previous literature estimate. Cyclopentadienone (CPDone) has been assumed to be an important intermediate in C5 ring oxidation even though it has not been unambiguously identified in the combustion environment. A detection limit of 20ppmv for CPDone in the present apparatus failed to note any CPDone. A set of mechanistic pathways for the C5 ring oxidation includes steps to avoid unrealistic CPDone production is presented. The complex mechanism illustrates the need for detailed models to understand the combustion of aromatics and soot precursors. The article stresses the importance of CPDyl in the formation of aromatic rings during combustion, which subsequently leads to polycyclic aromatic hydrocarbons (PAH) and soot precursors.

First principles study of Eu doped carbon nanotubes

The geometric and electronic structures of Eu doped single-walled carbon nanotubes (SWCNTs) have been studied using density functional theory. Three different doping configurations are considered. All of these configurations are stable upon relaxation, and Eu atom on the top of the inside hole site is the most favorable configuration for most nanotubes, except ( 3 , 3 ) CNT. The formation energies vary regularly with the same trend as in the Co and Fe doped cases. The electronic structures studies indicate that the charge transfer basically occurs between 5 d 6 s of Eu and the π 4 ∗ antibonding orbital of the C6 ring of the SWCNT. Eu atom is monovalent for the exohedral and substitutional doping, and for the endohedral doping of large radius nanotubes; it is bivalent for endohedral doping of ( 3 , 3 ) tube. As the radius increases, the net charges on Eu atom steadily decrease for exohedral and endohedral doping. The magnetic moments of Eu atoms are preserved in all of the configurations, but they vary with the radius of nanotube and adsorbing sites.

Poly(1,4‐cyclohexylenedimethylene 1,4‐cyclohexanedicarboxylate): Influence of stereochemistry of 1,4‐cyclohexylene units on the thermal properties

AbstractA series of poly(1,4‐cyclohexylenedimethylene 1,4‐cyclohexanedicarboxylate) (PCCD) samples, characterized by different cis/trans ratio of the 1,4‐cyclohexanedicarbonyl unit, have been synthesized and analyzed by thermogravimetry (TGA), calorimetry (DSC), and X‐ray diffraction (WAXD). The thermal stability results are good and are not affected by the stereochemistry of the 1,4‐cyclohexylene units. On the other hand, the thermal transitions are notably influenced by the cis/trans content. With the increment of the trans content the polymer changes from completely amorphous to semicrystalline material. Tg, Tm, and crystallinity increase. These results suggest that the trans configuration induces a better chain packing and higher symmetry, improving the crystallizability of the samples. The effect of the molecular structure on the thermal properties is analyzed by using a statistical approach. From the effective correlations found between stereochemistry of the C6 rings and transition temperatures it is possible to extrapolate that the configuration of 1,4‐cyclohexylene ring deriving from 1,4‐cyclohexanedicarboxylic acid or dimethyl 1,4‐cyclohexanedicarboxylate results to be the main element responsible for the thermal properties. This is due to the high rigidity of the 1,4‐cyclohexanedicarbonyl unit with respect to 1,4‐cyclohexanedimethyleneoxy unit, deriving from the diol. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 619–630, 2008

Study of Ir/WO 3/ZrO 2–SiO 2 ring-opening catalysts: Part II. Reaction network, kinetic studies and structure–activity correlation

The present paper is the second part of a systematic study of the influence of W and Ir loading on the activity of Ir/WO 3/ZrO 2–SiO 2 catalysts for the ring-opening reaction of naphthenic molecules using methylcyclohexane (MCH) as a model compound. A series of Si-stabilized tungstated zirconias, WO x /ZrO 2–SiO 2, containing up to 3.5 atom W/nm 2, was prepared. Ir-based catalysts containing up to 1.2 wt% were obtained by impregnation of these solids. Characterization of the metal dispersion and catalyst acidity was described in a previous article. The objective of the present study was to determine the best metal/acid balance for optimal performance of Ir/WO x /ZrO 2–SiO 2 catalysts in the ring-opening reaction of MCH. Monofunctional (acid WO x /ZrO 2–SiO 2 or metal Ir/ZrO 2–SiO 2) and bifunctional (Ir/WO 3/ZrO 2–SiO 2) catalysts were examined. Based on the analysis of the yields and products distributions, a reaction network was proposed, and kinetic data (e.g., activation energies, initial rates) were calculated. Correlations between characterization results obtained earlier (e.g., acidity, dispersion) and catalytic performance are also reported. The monofunctional acid catalysts WO x /ZrO 2–SiO 2 showed a low selectivity for ring opening. The ring-contraction activity developed for W surface density above a threshold value of 1 atom W/nm 2. This was attributed to the appearance and the development of a relatively strong Brönsted acidity monitored by infrared measurements. MCH ring contraction and C5 naphthene ring opening occur according to a classic acid mechanism. For low conversions, the monofunctional metal catalysts Ir/ZrO 2–SiO 2 exhibited significant selectivity for ring opening that decreased with increasing conversion. Because of the lack of ring-contraction products, the observed activity was attributed to the direct ring opening of the MCH. Ring opening and cracking occur according to a dicarbene mechanism. The study of MCH conversion on Ir/WO x /ZrO 2–SiO 2 catalysts indicated that MCH ring contraction to alkylcyclopentanes occurs before ring opening. The best yields for ring opening were obtained with the 1.2% Ir/WO x /ZrO 2 (1.5 atom of W/nm 2). Further increases in W surface density led to a decrease in the indirect ring-opening yield, attributed to a decrease in Ir dispersion. For bifunctional metal/acid catalysts, analysis of the mechanism is less straightforward. The activation energy for C6 ring contraction and indirect C6 ring opening is a function of the metal/acid ratio. For high ratios, indirect ring opening occurs essentially over metallic sites. A decrease in the metal/acid ratio enhances the contribution of acid mechanism.

P-Amino-cyclopentadienylidene-phosphoranes versus P-cyclopentadienyl-iminophosphoranes—tautomeric protic forms of a new bidentate CpPNligand system

The Staudinger reaction of cyclopentadienyl-phosphanes C5H5-PMe2 (P1), C5H5-PPh2 (P2), and C5Me4H-PMe2 (P3) with azides Me3SiN3, 1-AdN3 (Ad = 1-adamantyl) and DipN3 (Dip = 2,6-diisopropylphenyl) has been studied. The nature of the products depends on the substituents at the C5 ring, at the phosphorus and nitrogen atoms: A series of new P-amino-cyclopentadienylidene-phosphoranes 2-6 was synthesized by reactions of P1-P3 with 1-AdN3 (2-4) and DipN3 (5,6). In contrast, P-cyclopentadienyl-iminophosphoranes 1 and 7 were obtained as predominant tautomers by reaction of less CH-acidic P3 with less N-basic Me3SiN3 and DipN3. Both tautomers are protonated forms of ambident, potentially chelating constrained-geometry ligands. The molecular structures of three members of this "CpPN" ligand family, 3, 4 and 6, are characterized by X-ray crystallography.

Very Large Difference in Electronic Communication of Dimetal Species with Heterobiphenylene and Heteroanthracene Units

Two neutral compounds having [Mo2] units linked by squarate dianions, [Mo2(DAniF)3]2(mu4-C4O4) (DAniF = N,N'-di(p-anisyl)formamidinate) (1) and [Mo2(DmCF3F)3]2(mu4-C4O4) (DmCF3F = N,N'-di(m-trifluoromethylphenyl)formamidinate) (2), as well as the singly oxidized compound {[Mo2(DmCF3F)3]2(mu4-C4O4)}SbF6 (3) and the doubly oxidized species {[Mo2(DAniF)3]2(mu4-C4O4)}(TFPB)2 (TFPB = [B(3,5-(CF3)2C6H3)4]-) (4), were synthesized and structurally characterized. Electrochemical measurements of the two neutral species showed only very weak electronic interactions between the two dimolybdenum units linked by the squarate anion in contrast to what was observed in dioxolene analogues having C6 instead of C4 rings (J. Am. Chem. Soc. 2006, 128, 3281) which led to differences in comproportionation constants of over 108. In the squarate species, the pi electrons are localized within the carbonyl and dimetal units in the heterometallic six-membered Mo2O2C2 rings to minimize the antiaromaticity in the central C4 square. The oxidized species 3 and 4 are electronically localized in the time scale of the physical measurements. Calculations at the DFT level suggested that the energy mismatch of the frontier orbitals of the linker and dimetal units contributes to the weak communication between the Mo2 units. For the doubly oxidized complex 4, DFT calculations gave a J value of -130 cm(-1) which suggests that the two unpaired electrons are only weakly antiferromagnetically coupled, as shown by magnetic studies (J = -121 cm(-1)).

Density Functional Theoretical Studies on Polyaniline/HNb3O8 Layered Nanocomposites

AbstractA theoretical study of polyaniline (PANI)/HNb3O8 layered nanocomposites has been performed based on ab initio calculations and experimental data. The Brønsted acidity of the layered niobic acid, and the interaction between the interlayered polyaniline molecules and the inorganic slabs in PANI/HNb3O8 nanocomposites, have been investigated. For the intercalation process of organic species into layered niobic acid, it is important to clarify whether the source of Brønsted acidity arises from the interlayered or hydrated protons. Thus, three inorganic layer structures, KNb3O8, HNb3O8, and HNb3O8·H2O, are evaluated, and the results show that there is only a minor contribution to the total acidity if the hydrogen is tightly bound by the inorganic slab. After the interlayered aniline monomers are polymerized within the acidic inorganic layers, two orientated structures of PANI molecules are calculated in which the interlayered C6 rings are perpendicular and parallel to the inorganic slabs, respectively, based on the experimental results. In comparison, PANI molecules in the latter orientation are placed in a relatively narrower interlayer space, and the hydrated proton cannot simultaneously form two effective hydrogen bonds with the O atom of Nb3O8– and an N atom of the PANI molecule because of the orientation requirement of the hydrogen bond. The interlayered hydrated proton cannot effectively transfer electrons between the PANI molecule and the inorganic slab. A similar conclusion is also reached from a detailed analysis of band structure and density of states (DOS). The calculated results are in good agreement with the experimental fact that a relatively higher conductivity is apparent in the former rather than in the latter.

Kinetics and mechanism of the oxidative cleavage of ketones by quinolinium dichromate

The kinetics of the oxidation of ketones (cyclic and arylalkyl) by quinolinium dichromate (QDC), in an acid medium, has been investigated. The rate of the reaction was proportional to the concentrations of the ketone, QDC, and acid. The order of reactivity for the cyclic ketones was C6 > C8 > C5 > C7 (ring size) and acetophenone > propiophenone > butyrophenone > valerophenone (arylalkyl ketones). A kinetic isotope effect, k H/k D = 5.80, was observed (cyclohexanone and cyclohexanone-d4). The rate data have been rationalized using conformational considerations. The mechanism involved the attack of the protonated QDC on the enol form (of the ketone), in the rate-determining step, forming a cyclic chromate ester. Subsequent cleavage of the carbon-carbon bond of the ester yielded carboxylic acids as the products.

The Aromatization of C5 Rings on a Heteronuclear Cluster

AbstractThe reaction of the heteronuclear cluster RuOs3(μ‐H)2(CO)13 with saturated and unsaturated C5 rings led to the aromatization of the rings to afford the clusters RuOs3(μ‐H)(CO)9(μ‐CO)2(η5‐C5R4R′). However, the reaction with cyclopentene gave the cluster RuOs3(μ‐H)3(CO)11(μ,η1:η2‐C5H7) via C–H activation of an sp2 carbon instead. Thermolysis of two of the products, RuOs3(μ‐H)(CO)9(μ‐CO)2(η5‐Cp′) and RuOs3(μ‐H)(CO)9(μ‐CO)2(η5‐C5H4SiMe3), led to their isomerization to butterfly clusters.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Bidirectional Ring‐Opening and Ring‐Closing of Cationic 1,2‐Dithienylcyclopentene Molecular Switches Triggered with Light or Electricity

AbstractEither light or electricity can be used to trigger the reversible cyclization reactions of three bis(N‐methylpyridinium)dithienylethene derivatives that differ from each other by the presence of either thiophene rings or methyl groups at the two carbon atoms of the photoresponsive hexatriene system involved in forming the new C–C bond. All three derivatives undergo ring‐closing isomerization reactions when irradiated with UV light (365 nm) or when electrochemically reduced (–1.0 V). All three derivatives can also be ring‐opened by irradiating them with visible light (> 490 nm) or by electrochemically oxidizing them (+1.5 V). The presence of additional thiophene rings attached to the two C2 ring positions of the dithienylethene (DTE) backbone enhances the electrochromic behavior, while methyl groups in these positions results in improved photochromic performance. The nature of these groups also greatly affects the thermal properties of the compounds in their ground states. Replacing each methyl group at the C2 ring positions with a thiophene ring systematically lowers the activation energy of spontaneous ring‐opening by 8 kJ mol–1, which correlates with the enhanced efficiency of the oxidative ring‐opening reactions and with the limited photochromism of the thiophene‐functionalized derivative.

Impact of internal electron transfer on the structure of C74 encapsulating Sc and La metal atom impurities

AbstractFrontier orbital theory as well as the Hückel 4n + 2 rule are discussed as guiding principles for the design and the interpretation of metallofullerene architecture where systems of the form Mi@C74 (M = Sc, La; i = 1,2) serve as examples. Transfer of electrons from the metal impurities to the fullerene enclosure populates preferentially the low‐lying unoccupied molecular orbitals of the cage. It further tends to induce aromaticity in the C5 rings neighboring the impurity sites. These observations are used to derive systematically stable structures of the studied mono‐ and dimetallofullerenes. Various geometries and spin states of M2@C74 (M = Sc, La) are considered, and novel ground state candidates are proposed. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007

Synthesis and crystal structure of a second polymorph of N,N′-bis(salicylidene)-3,5,3′,5′-tetramethyl-biphenyl-4,4′-diamine

The Schiff base compound N,N′-bis(salicylidene)-3,5,3′,5′-tetramethyl-biphenyl-4,4′-diamine was synthesized and crystal structure was determined by single-crystal X-ray diffractometry. The result shows that there is another polymorphic form (B) in structure besides published one (A) [1]. In structure B, there are four aromatic rings. The dihedral angles between the phenol rings and the adjacent dimethylbenzene rings are distinctly larger than that formed by the dimethylbenzene rings, possibly as a result of the steric hindrance of the methyl groups and the presence of intramolecular O-H…N hydrogen bonds. The remarkable defference between A and B lies in the angles of C1–C6 ring and C25–C30 ring, which are 51.64(13)° and 7.40(7)° in B and A, respectively. Crystal data for the title compolex C30H27N2O2: Monoclinic, P2(1)/c, a = 14.346(3) A, b = 12.258(2) A, c = 14.265(3) A; β = 99.515(4)°, V = 2474.1(7) A3, Z = 4.

Synthesis of (1′R,3S,4S)‐3‐[1′‐(tert‐Butyldimethylsilyloxy)ethyl]‐ 4‐(cyclopropylcarbonyloxy)azetidin‐2‐one

AbstractThe novel carbapenem precursor 1e has been synthesized from L‐threonine, cyclopropyl methyl ketone and benzhydrylamine (for the introduction of the azetidinone N‐protecting group). Two independently prepared building blocks – sodium (2R,3R)‐2,3‐epoxybutyrate as a mixed salt with NaBr (2b) and N‐(benzhydryl)aminomethyl cyclopropyl ketone (4e) – were coupled to give (2R,3R)‐N‐(benzhydryl)‐N‐(2‐cyclopropyl‐2‐oxoethyl)‐2,3‐epoxybutyramide (8e). This key intermediate gave a regio‐ and stereoselective C3–C4 ring closure on LiHMDS treatment in THF at 0 °C to yield(1′R,3S,4S)‐4‐cyclopropylcarbonyl‐1‐diphenylmethyl‐3‐(1‐hydroxyethyl)azetidin‐2‐one (13e). N‐Deprotection of 13e was performed by photochemical bromination and subsequent hydrolysis. The resulting (1′R,3S,4S)‐4‐(cyclopropylcarbonyl)‐3‐(1‐hydroxyethyl)azetidin‐2‐one (23e) reacted in a Baeyer–Villiger oxidation with a total control of the regioselectivity (due to the poor migratory aptitude of the cyclopropyl group) to furnish (1′R,3S,4S)‐3‐(1‐hydroxyethyl)‐4‐(cyclopropylcarbonyloxy)azetidin‐2‐one (24e), subsequent O‐silylation achieving the total synthesis of 1e (title compound).(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)

Adsorption geometry and core excitation spectra of three phenylpropene isomers on Cu(111)

Theoretical C 1s near edge x-ray absorption fine structure (NEXAFS) spectra for the C(9)H(10) isomers trans-methylstyrene, alpha-methylstyrene, and allylbenzene in gas phase and adsorbed at Cu(111) surfaces have been obtained from density functional theory calculations where adsorbate geometries were determined by corresponding total energy optimizations. The three species show characteristic differences in widths and peak shapes of the lowest C 1s-->pi(*) transitions which are explained by different coupling of the pi-electron system of the C(6) ring with that of the side chain in the molecules as well as by the existence of nonequivalent carbon centers. The adsorbed molecules bind only weakly with the substrate which makes the use of theoretical NEXAFS spectra of the oriented free molecules meaningful for an interpretation of experimental angle-resolved NEXAFS spectra of the adsorbate systems obtained in this work. However, a detailed quantitative account of relative peak intensities requires theoretical angle-resolved NEXAFS spectra of the complete adsorbate systems which have been evaluated within the surface cluster approach. The comparison with experiment yields almost perfect agreement and confirms the reliability of the calculated equilibrium geometries of the adsorbates. This can help to explain observed differences in the catalytic epoxidation of the three molecules on Cu(111) based on purely geometric considerations.

Characteristics of Antiaromatic Ring π Multi-Hydrogen Bonds in (H2O)n−C4H4(n= 1, 2) Complexes

By counterpoise-corrected optimization method, the six antiaromatic ring pi multi-hydrogen bond structures with diversiform shapes for (H2O)n-C4H4 (n = 1,2) have been obtained at the MP2/aug-cc-pVDZ level. At the CCSD(T)/aug-cc-pVDZ level, the interaction energy obtained mainly depends on the numbers of H2O and fold numbers of the pi multi-hydrogen bond. The interaction energy order is -2.342 (1a with pi mono-hydrogen) < -2.777 (1b with pi bi-hydrogen) << -4.683 (2a with pi bi-hydrogen) < -4.734 (2b with pi tri-hydrogen) < -4.782 (2c with pi tri-hydrogen) < -5.009 kcal/mol (2d with pi tetra-hydrogen bond). Strangely, why is the interaction energy of the pi bi-hydrogen bond in 1b close to that of the pi mono-hydrogen bond in 1a (their difference is only 15.7%)? The reason is that a pi-type H-bond (as an accompanying interaction) between two lone pairs of the O-atom and a near pair of H-atoms of C4H4 exists shoulder by shoulder in structures 1a, 2a, 2b, and 2c and contributes to the interaction energy. Another accompanying interaction, a repulsive interaction between the pi H-bond (using the H-atom(s) of H2O) and the near pair of H-atoms of C4H4, is also found. For the structures and interaction energies, the pi-type H-bond produces four effects: bending the strong pi H-bond, attracting the pair of H-atoms of C4H4 so that they deviate from the C4 ring plane, showing the interaction energy contribution, and bringing the larger electron correlation contribution. The repulsive interaction also produces four effects: pushing the pair of H-atoms of C4H4 so that they deviate from its ring plane, elongating the distance of the pi H-bond, promoting the formation of pi-type H-bond, and slightly influencing the interaction energy. In the present paper, one C=C bond with two H2O (over and below the ring plane) forms a pi H-bond link in two ways: a strong-weak pi H-bond link and a strong-strong pi H-bond link. The stability contribution of the former is more favorable than the latter. One H2O forms a pi H-bond with C4H4 in two ways. One strong pi H-bond part (over or below the ring plane) always is accompanied by another H-bond part. The accompanying part is either a weak pi H-bond or pi-type H-bond.

5-(p-Tolylsulfonyl)-3-oxa-5-azatricyclo[5.2.1.04,8]decane

In the title compound, C15H19NO3S, the tricyclodecane part of the molecule can be described in terms of three rings. The C4N ring is in an envelope conformation, as is the C5 ring. The C5O ring adopts a boat conformation. There are no inter- or intramolecular hydrogen-bonding interactions.