Reactive properties of trans-dichlorooxirane in relation to the contrasting carcinogenicities of vinyl chloride and trans-dichloroethylen

Our objective in this work is to gain insight into the contrasting carcinogenic activities of vinyl chloride (definitely carcinogenic) and trans-dichloroethylene (apparently inactive). The initial metabolic step for each molecule is believed to be epoxidation of the double bond, and there is evidence indicating that for vinyl chloride, this epoxide (chlorooxirane) is its ultimate (direct-acting) carcinogenic form. This article presents the findings of a computational study of the reactive properties of trans-dichlorooxirane (the epoxide of trans-dichloroethylene). An ab initio SCF -MO procedure was used to determine the energy requirements for stretching the C? O and C? Cl bonds (S_N1 reactivity) and to study the epoxide's S_N2 interactions with ammonia, taken as a model nucleophile. The starting points were the oxygen- and chlorine-protonated forms of the epoxide. The structure of the system was reoptimized at each step along the various reaction pathways. The results of this work are compared to an analogous earlier study of the reactive properties of chlorooxirane. The chlorineprotonated C? Cl bonds are found to have much lower energy barriers to stretching than do the oxygen-protonated C? O bonds. In the S_N2 processes, intermediate complexes are formed with ammonia by both the oxygen- and the chlorine-protonated epoxides; the latter complexes are the more stable. Based on our results, we propose two mechanisms (one S_N1 and the other S_N2) whereby trans-dichlorooxirane can interact with N₇ of guanine to produce an adduct analogous to one formed by chlorooxirane, which has been found to be the primary in vivo DNA alkylation product of vinyl chloride and to which has been attributed the carcinogenicity of the latter. Overall, trans-dichlorooxirane is found to be chemically more reactive than chlorooxirane; this may help to account for the much lesser carcinogenic and mutagenic activities of trans-dichloroethylene, since the epoxide may be reacting with other cellular nucleophiles before it reaches the key site(s) at which the carcinogenic or mutagenic interaction would occur. We also offer some speculations concerning other possible factors related to the differing carcinogenicities of vinyl chloride and trans-dichloroethylene, such as ease of epoxide formation and the likelihood of oxygen protonation.     

Poly­sulfonyl­amines. CXLV.

The prominent features in the molecular structure of the title compound (alternative name: 2‐diethyl­carbamoyl‐1,1,3,3‐tetraoxo‐1,3,2‐benzodi­thia­zole), C₁₁H₁₄N₂O₅S₂, arise in the urea moiety S₂N—C(O)—N′C₂: the sum of the angles at N is 332.3 (1)°, the N—C(O)—N′C₂ unit is planar, and distances N—C(O) = 1.494 (3) Å, N′—C(O) = 1.325 (2) Å and C—O = 1.215 (2) Å. The mol­ecules are associated via five C—H?O hydrogen bonds to form layers parallel to the yz plane. This compound and its di­methyl homologue, which were synthesized by treating the silver salt of o‐benzene­disulfon­imide with carbamoyl chlorides, are prone to rapid hydro­lysis at the weak N—C(O) bond. For both mol­ecules, the rotational barrier about the partial N′—C(O) double bond is ca 50 kJ mol^?1 at 250 K (from dynamic ¹H NMR experiments).     

Multicentre hydrogen bonds in a 2:1 aryl­sulfonyl­imidazol­one ­hydro­chloride salt

The title compound, (S)‐(+)‐4‐[5‐(2‐oxo‐4,5‐di­hydro­imidazol‐1‐yl­sulfonyl)­indolin‐1‐yl­carbonyl]­anilinium chloride (S)‐(+)‐1‐[1‐(4‐amino­benzoyl)­indoline‐5‐sulfonyl]‐4‐phenyl‐4,5‐di­hydro­imidazol‐2‐one, C₂₄H₂₃N₄O₄S⁺·Cl^?·C₂₄H₂₂N₄O₄S, crystallizes in space group C2 from a CH₃OH/CH₂Cl₂ solution. In the crystal structure, there are two different conformers with their terminal C₆ aromatic rings mutually oriented at angles of 67.69 (14) and 61.16 (15)°. The distances of the terminal N atoms (of the two conformers) from the chloride ion are 3.110 (4) and 3.502 (4) Å. There are eight distinct hydrogen bonds, i.e. four N—H?Cl, three N—H?O and one N—H?N, with one N—H group involved in a bifurcated hydrogen bond with two acceptors sharing the H atom. C—H?O contacts assist in the overall hydrogen‐bonding process.     

The complexes of vanadium(IV) oxydichloride with anisidines,toluidines, quinolines,tetrahydropyran, and tetrahydrothiophene

VOCl₂ was prepared by reducing VOCl₃ with sulphur under an atmosphere of dry nitrogen. The VOCl₂ with tetrahydrofuran formed the complex VOCl₂(C₄H₈O)₂. The complexes of VOCl₂ with anisidines, toluidines, quinolines, tetrahydropyran and tetrahydrothiophene were prepared by the reaction of VOCl₂(C₄H₈O)₂ and the respective ligand. Infrared spectra of the complexes were determined in nujol and hexachlorobutadiene mulls and assignments of vanadium-oxygen double bond, v(V?O), vanadium-nitrogen, v(V? N), vanadium-oxygen, v(V? O), vanadium-sulphur, v(V? S) and vanadiumchlorine, v(V? Cl), stretching vibrations made. The possible structural formations of the complexes are proposed.     

Protonation products of pentaaminopentane as novel building blocks for hydrogen‐bonded networks

The structures of 3‐amino‐1,2R,4S,5‐tetra­ammoniopentane tetrachloride monohydrate, C₅H₂₁N₅⁴⁺·4Cl^?·H₂O, and 1,2R,3,4S,5‐penta­ammoniopentane tetra­chloro­zincate tri­chlor­ide monohydrate, (C₅H₂₂N₅)[ZnCl₄]Cl₃·H₂O, have been determined from single‐crystal X‐ray diffraction data. Both compounds show a complex network of N—H?O, O—H?Cl and N—H?Cl hydrogen bonds. There are a total of 14 H atoms of the tetra‐cation and 15 H atoms of the penta‐cation available for hydrogen bonding. However, due to the particular shape of the primary linear poly­ammonium cations, only a certain number of H atoms can be involved in hydrogen‐bond formation. It is further shown that hydrogen bonding has an influence on the conformation of such alkyl­ammonium cations.     

Calculated properties of some possible vinyl chloride metabolites

There is considerable evidence indicating that the carcinogenic action of vinyl chloride involves metabolic conversion to the epoxide (chlorooxirane) as the initial step. In order to learn more about its subsequent behavior, we have computed structures, energies and other properties for two different protonated forms of the epoxide, and also for two possible rearrangement products, chloroacetaldehyde and acetyl chloride. An ab initio SCF -MO procedure (GAUSSIAN 70) was used. Oxygen protonation is found to weaken both C? O bonds, the effect being greater for the bond involving the carbon bearing the chlorine. Chlorine protonation leads to a marked weakening of the C? Cl bond; this suggests a possible loss of HCl, leaving behind a carbonium ion (and possible alkylating agent or rearrangement precursor). Thus, while C? O bond breaking is doubtless an important reaction pathway for chlorooxirane, our results indicate that attention should also be focused upon the C? Cl bond; its rupture may conceivably be a key step in the biological action of vinyl chloride.     

(1R,2R)‐1,2‐Di­phenyl‐1,2‐bis(8‐quinoline­sulfonyl­amino)ethyl­enedi­amine–acetone (1/1)

The crystal structure of the new chiral complex (1R,2R)‐1,2‐di­phenyl‐1,2‐bis(8‐quinoline­sulfonyl­amino)‐ ethyl­enedi­amine–acetone (1/1), C₃₂H₂₆N₄O₄S₂^.C₃H₆O, is reported. The conformation of the C₃₂H₂₆N₄O₄S₂ (BQSDA) mol­ecule is determined by a bifurcated N—H?N hydrogen‐bond system. The acetone of solvation is linked to the BQSDA mol­ecule by an N—H?O hydrogen bond.     

Cover Feature: An Exploration of the Hydrogen Bond Donor Ability of Ammonia (ChemPhysChem 20/2023)

Ammonia is an important molecule due to its wide use in the fertiliser industry. It is also used in aminolysis reactions. Theoretical studies of the reaction mechanism predict that in reactive complexes and transition states, ammonia acts as a hydrogen bond donor forming N−H⋅⋅⋅O hydrogen bond. Experimental reports of N−H⋅⋅⋅O hydrogen bond, where ammonia acts as a hydrogen bond donor are scarce. Herein, the hydrogen bond donor ability of ammonia is investigated with three chalcogen atoms i. e. O, S, and Se using matrix isolation infrared spectroscopy and electronic structure calculations. In addition, the chalcogen bond acceptor ability of ammonia has also been investigated. The hydrogen bond acceptor molecules used here are O(CH₃)₂, S(CH₃)₂, and Se(CH₃)₂. The formation of the 1 : 1 complex has been monitored in the N−H symmetric and anti-symmetric stretching modes of ammonia. The nature of the complex has been delineated using Atoms in Molecules analysis, Natural Bond Orbital analysis, and Energy Decomposition Analysis. This work presents the first comparison of the hydrogen bond donor ability of ammonia with O, S, and Se.     

Molecular‐Level Understanding of Ground‐ and Excited‐State O?H⋅⋅⋅O Hydrogen Bonding Involving the Tyrosine Side Chain: A Combined High‐Resolution Laser Spectroscopy and Quantum Chemistry Study

The present study combines both laser spectroscopy and ab initio calculations to investigate the intermolecular O? H???O hydrogen bonding of complexes of the tyrosine side chain model chromophore compounds phenol (PH) and para‐cresol (pCR) with H₂O, MeOH, PH and pCR in the ground (S₀) state as well as in the electronic excited (S₁) state. All the experimental and computational findings suggest that the H‐bond strength increases in the S₁ state and irrespective of the hydrogen bond acceptor used, the dispersion energy contribution to the total interaction energy is about 10–15 % higher in the S₁ state compared to that in the S₀ state. The alkyl‐substituted (methyl; +I effect) H‐bond acceptor forms a significantly stronger H bond both in the S₀ and the S₁ state compared to H₂O, whereas the aryl‐substituted (phenyl; ?R effect) H‐bond donor shows a minute change in energy compared to H₂O. The theoretical study emphasizes the significant role of the dispersive interactions in the case of the pCR and PH dimers, in particular the C? H???O and the C? H???π interactions between the donor and acceptor subunits in controlling the structure and the energetics of the aromatic dimers. The aromatic dimers do not follow the acid–base formalism, which states that the stronger the base, the more red‐shifted is the X? H stretching frequency, and consequently the stronger is the H‐bond strength. This is due to the significant contribution of the dispersion interaction to the total binding energy of these compounds.     

7‐Vinyl‐8‐aza‐7‐de­aza‐2′‐deoxy­adenosine monohydrate

In the title compound, 4‐amino‐1‐(2‐deoxy‐β‐d ‐eythro‐pento­furan­osyl)‐3‐vinyl‐1H‐pyrazolo­[3,4‐d]­pyrimidine monohydrate, C₁₂H₁₅N₅O₃·H₂O, the conformation of the gly­cosyl bond is anti. The furan­ose moiety is in an S conformation with an unsymmetrical twist, and the conformation at the exocyclic C—C(OH) bond is +sc (gauche, gauche). The vinyl side chain is bent out of the heterocyclic ring plane by 147.5 (5)°. The three‐dimensional packing is stabilized by O—H·O, O—H·N and N—H·O hydrogen bonds.     

α‐Halogenoacetanilides as Hydrogen‐Bonding Organocatalysts that Activate Carbonyl Bonds: Fluorine versus Chlorine and Bromine

α‐Halogenoacetanilides (X=F, Cl, Br) were examined as H‐bonding organocatalysts designed for the double activation of C?O bonds through NH and CH donor groups. Depending on the halide substituents, the double H‐bond involved a nonconventional C?H???O interaction with either a H?CX_n (n=1–2, X=Cl, Br) or a H?C_Ar bond (X=F), as shown in the solid‐state crystal structures and by molecular modeling. In addition, the catalytic properties of α‐halogenoacetanilides were evaluated in the ring‐opening polymerization of lactide, in the presence of a tertiary amine as cocatalyst. The α‐dichloro‐ and α‐dibromoacetanilides containing electron‐deficient aromatic groups afforded the most attractive double H‐bonding properties towards C?O bonds, with a N?H???O???H?CX₂ interaction.     

Dichloro[1,1′‐(5,9‐dithia‐2,12‐diazoniatrideca‐1,12‐diene‐1,13‐diyl)dinaphthalen‐2‐olato‐κ2O,O′]dimethyltin(IV) acetonitrile solvate

Reaction of the potentially hexadentate ligand 1,9‐bis(2‐hydroxy‐1‐naphthalene­methyl­imino)‐3,7‐di­thia­nonane with di­methyl­tin chloride gave the title 1:1 adduct, in which the long ligand wraps around the SnCl₂Me₂ unit and in which the stereochemistry is fully trans. This compound crystallizes from aceto­nitrile as the 1:1 solvate [Sn(CH₃)₂(C₂₉H₃₀N₂­O₂S₂)Cl₂]·­C₂H₃N. During the reaction, the hydroxyl protons move to the N atoms. Most of the chemically equivalent bond lengths agree to within experimental uncertainty, but the Sn—Cl bond that is inside the ligand pocket is substantially longer than the Sn—Cl bond that points away from the long ligand [2.668 (1) versus 2.528 (1) Å]. The O—Sn—O angle is 166.0 (1)°. Comparison of the Sn—O, C—O and aryl C—C bond lengths with those of related compounds shows that the most important resonance forms for the Schiff base aryl­oxide ligand are double zwitterions, but that the uncharged resonance forms having carbonyl groups also contribute significantly.     

Vinyl polymerization initiated by system of organic halides and tertiary amines

A study of the polymerization of vinyl monomers with binary systems of tertiary amines and various organic halides containing chemical bonds such as C? Cl, N? Cl, O? Cl, S? Cl, and Si? Cl has been made at 60°C. Some of the binary systems were found to be effective as radical initiator in the polymerization of methyl methacrylate. The relative initiating activities of the halides in the presence of dimethylaniline were found to be in the following order: tert-C₄H₉OCl > n-C₄H₉NCl₂ > (n-C₄H₉)₂NCl ? CH₃SiCl₃ ? C₆H₅SiCl₃ > C₆H₅SO₂Cl > C₆H₅Cl > C₆H₅PCl₂. Styrene and vinyl acetate polymerized only with the initiator system of dimethylaniline and benzyl chloride. Tri-n-butylamine was less active than dimethylaniline. Pyridine and 4-vinylpyridine, in combination with some organic halides, also initiated the polymerization of methyl methacrylate. The N-vinylcarbazole–benzenesulfonyl chloride system, in the presence of methyl methacrylate, gave only the homopolymer of N-vinylcarbazole.     

μ‐1,4‐Benzenedicarboxylato‐bis[trans‐aqua(1,4,8,11‐tetraazacyclotetradecane)nickel(II)] diperchlorate forms a three‐dimensional hydrogen‐bonded framework

The title compound, [Ni₂(C₈H₄O₄)(C₁₀H₂₄N₄)₂(H₂O)₂](ClO₄)₂, contains two independent octahedral Ni^II centres with trans‐NiN₄O₂ chromophores. The bridging benzene­dicarboxyl­ate ligand is bonded to the two Ni atoms, each via one O atom of each carboxyl­ate, while the other O atom participates in an intramolecular N—H?O hydrogen bond, forming an S(6) motif. The cations are linked to the perchlorate anions via O—H?O and N—H?O hydrogen bonds [O?O 2.904 (6) and 2.898 (6) Å; O—H?O 158 (6) and 165 (6)°; N?O 3.175 (7) and 3.116 (7) Å; N—H?O 168 and 166°] to form molecular ladders. These ladders are linked by further O—H?O and N—H?O hydrogen bonds [O?O 2.717 (6) and 2.730 (5) Å; O—H?O 170 (4) and 163 (6)°; N?O 3.373 (7) and 3.253 (7) Å; N—H?O 163 and 167°] to form a continuous three‐dimensional framework. The perchlorate anions both participate in three hydrogen bonds, and both are thus fully ordered.     

The diastereoisomers 2‐[(S/R)‐2‐chloro‐3‐quinolyl]‐2‐[(R)‐1‐(4‐methoxyphenyl)ethylamino]acetonitrile at 100 K

In the structures of the two enantiopure diastereoisomers of the title compound, C₂₀H₁₈ClN₃O, which crystallize in different space groups, the molecules are very similar as far as bond distances and angles are concerned, but more substantial differences are observed in some torsion angles. The crystal structures of both molecules can be described as zigzag layers along the c axis. The packing is stabilized by hydrogen‐bond interactions of N—H...O, C—H...Cl and C—H...π types for 2‐[(R)‐2‐chloro‐3‐quinolyl]‐2‐[(R)‐1‐(4‐methoxyphenyl)ethylamino]acetonitrile, and of N—H...N, C—H...O and C—H...π types for 2‐[(S)‐2‐chloro‐3‐quinolyl]‐2‐[(R)‐1‐(4‐methoxyphenyl)ethylamino]acetonitrile, resulting in the formation of two‐ and three‐dimensional networks.     

Hydro­gen‐bonded adducts of ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol): monomeric and dimeric 1:1 adducts with 1,2‐bis(4‐pyridyl)­ethane and 1,2‐­diamino­ethane

In ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol)–4,4′‐ethyl­enedi­pyridine (1/1), [Fe(C₁₈H₁₅O)₂]·C₁₂H₁₂N₂, there is an intra­molecular O—H?O hydrogen bond in the ferrocenediol component and a single O—H?N hydrogen bond linking the two components into a finite monomeric adduct. Ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol)–ethyl­enedi­amine (1/1), [Fe(C₁₈H₁₅O)₂]·C₂H₈N₂, crystallizes with Z′ = 2 in space group P, and there are two independent four‐component aggregates in the structure, both of which are centrosymmetric. In the first type of aggregate, the molecular components are linked by O—H?N and N—H?O hydrogen bonds, in which both di­amine N atoms participate; in the second type of aggregate, the di­amine component is disordered over two sets of sites, but only one N atom is involved in the hydrogen bonding.     

Hydro­gen‐bonded adducts of ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol): a finite cyclic 1:1 adduct with 2,2′‐dipyridyl­amine

In ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol)–2,2′‐dipyridyl­amine (1/1), [Fe(C₁₈H₁₅O)₂]·C₁₀H₉N₃, (I), there is an intramolecular O—H?O hydrogen bond [H?O 2.03 Å, O?O 2.775 (2) Å and O—H?O 147°] in the ferrocenediol component, and the two neutral molecular components are linked by one O—H?N hydrogen bond [H?N 1.96 Å, O?N 2.755 (2) Å and O—H?N, 157°] and one N—H?O hydrogen bond [H?O 2.26 Å, N?O 3.112 (2) Å and N—H?O 164°] forming a cyclic R(8) motif. One of the pyridyl N atoms plays no part in the intermolecular hydrogen bonding, but participates in a short intramolecular C—H?N contact [H?N 2.31 Å, C?N 2.922 (2) Å and C—H?N 122°].     

An ab initio study of the influence of substituents and intramolecular hydrogen bonding on the carbonyl bond length and stretching force constant. I. Monosubstituted carbonyl compounds

The C?O bond length and f_C?O,C?O, the corresponding harmonic stretching force constant, are calculated ab initio using the 4-31G basis set (augmented by polarization functions on the sulfur and chlorine) with full geometry optimization for the monosubstituted carbonyl compounds RCHO, where R = H, CHO, CH?CH₂, CO₂H, CH?CHOH, OH, OC(?O)OH, OOH, S? H, Li, F, Cl, and NH₂. Straight-line relationships are found in plots of ln[f_C?O,C?O] vs. ln[r_C?O] for the series of compounds in which carbon atoms and oxygen atoms are bonded directly to the carbonyl carbon, in accordance with the empirical expression f = C′/rⁿ. The slopes and intercepts give n = 7.62 and 6.47, C′ = 62.6 and 48.6, for the lines with carbon and oxygen as the atom bonded directly to the carbonyl carbon, respectively. The point for formaldehyde lies very close to the C line, whereas the points for SH, Li, F, Cl, and NH₂ lie closer to the O line.     

Racemic and chiral 1‐[N‐(chloro­acetyl)carbamoylamino]‐2,3‐dihydro‐1H‐inden‐2‐yl chloroacetate

In the racemic crystals of (1S,2R)‐ or (1R,2S)‐1‐[N‐(chloro­acetyl)­carbamoyl­amino]‐2,3‐di­hydro‐1H‐inden‐2‐yl chloro­acetate, C₁₄H₁₄Cl₂N₂O₄, (I), the enantiomeric mol­ecules form a dimeric structure via the N—H?O cyclic hydrogen bond of the carbamoyl moieties. In the chiral crystals of (—)‐(1S,2R)‐1‐[N‐(chloro­acetyl)­carbamoyl­amino]‐2,3‐di­hydro‐1H‐inden‐2‐yl chloro­acetate, C₁₄H₁₄Cl₂N₂O₄, (II), the N—­H?O intermolecular hydrogen bond forms a zigzag chain around the twofold screw axis. The melting points and calculated densities of (I) and (II) are 446 and 396 K, and 1.481 and 1.445 Mg m^?3, respectively.     

Hydro­gen‐bonded adducts of ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol): monomeric and polymeric adducts with 1,2‐bis(4‐pyridyl)­ethene and 1,6‐di­amino­hexane

In the adduct ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol)–1,2‐bis(4‐pyridyl)­ethene (1/1), [Fe(C₁₈H₁₅O)₂]·C₁₂H₁₀N₂, there is an intramolecular O—H?O hydrogen bond in the ferro­cene­diol component and a single O—H?N hydrogen bond linking the diol to the di­amine, which is disordered over two sets of sites, so forming a finite monomeric adduct. In the adduct ferrocene‐1,1′‐diyl­bis­(di­phenyl­methanol)–1,6‐di­amino­hexane (2/1), 2[Fe(C₁₈H₁₅O)₂]·C₆H₁₆N₂, the amine lies across a centre of inversion in space group P. There is an intramolecular O—H?O hydrogen bond in the ferrocenediol, and the molecular components are linked by O—H?N and N—H?O hydrogen bonds, one of each type, into a C(13)[R(12)] chain of rings.