2(S)‐Amino‐3‐[1H‐imidazol‐4(5)‐yl]­propyl cyclo­hexylmethyl ether di­hydro­chloride and 2(S)‐amino‐3‐[1H‐imidazol‐4(5)‐yl]­propyl 4‐bromo­benzyl ether di­hydro­chloride

(Cyclo­hexyl­methyl­oxy­methyl)(1H‐imidazol‐4‐io­methyl)‐(S)‐ammonium dichloride, C₁₃H₂₅N₃O⁺·2Cl^?, and (4‐bromo­benzyl)(1H‐imidazol‐4‐io­methyl)‐(S)‐ammonium dichloride, C₁₃H₁₈BrN₃O⁺·2Cl^?, are model compounds with different biological activities for evaluation of the hist­amine H3‐receptor activation mechanism. Both title compounds occur in almost similar extended conformations.     

N-Heteroaralkyl substituted α-amidinium thiolsulfates

The syntheses of a number of N-substituted α-amidinium thiolsulfates, CH₂(S₂O₃^?)-C(=NH₂⁺)NH(CH₂)nR are described, where n was varied from 1 to 3 and R represents such heteroaryl groups as 2-furyl, 2-thienyl, 3-indolyl and 2-, 3- and 4-pyridyl. The preparation of S-(2-imidazolinemethyl)thiolsulfuric acid, as an example of an N, N'-disubstituted α-amidinium thiolsulfate, is also reported.     

Metall-Schwefelstickstoff-Verbindungen. 19. Neue Komplexe von CuI mit dem S3N−-Chelatliganden Darstellung und Struktur von [Ph4As][Cu(S3N)(CN)], [(Ph3P)2N][Cu(S3N)(S7N)] und [Ph4As]2[(S3N)Cu(S2O3)Cu(S3N)]

Metal Sulfur-Nitrogen Compounds. 19. Novel Complexes of Cu^I with the S₃N^? Chelate Ligand. Preparation and Structure of [Ph₄As][Cu(S₃N)(CN)], [(Ph₃P)₂N][Cu(S₃N)(S₇N)], and [Ph₄As]₂[(S₃N)Cu(S₂O₃)Cu(S₃N)] In alkaline media S₇NH reacts with Cu salts to yield different products. With Cu(CN) the ion [Cu(S₃N)(CN)]^? is formed, which was isolated as the [Ph₄As]⁺ salt. The crystals are monoclinic, space group P2₁/c, a = 10.499(5), b = 13.418(6), c = 18.032(8) Å, β = 91.84°(3), Z = 4. Besides the known complex ions [Cu(S₃N)₂]^? and [Cu(S₃N)Cl]^? still some more may be obtained when CuCl₂ is reacted with S₇NH: Under special conditions the S₇N ring is partly preserved, and [Cu(S₃N)(S₇N)]^? is formed. Its sparingly soluble [(Ph₃P)₂N]⁺ salt is monoclinic, space group P2₁/n, a = 9.335(6), b = 30.984(11), c = 15.108(8) Å, β = 102.87°(4), Z = 4. Using a longer reaction time a dinuclear complex [(S₃N)Cu(S₂O₃)Cu(S₃N)]^{? ?} results from the reaction of CuCl₂ with S₇NH. The two Cu atoms are bridged by an S atom of the S₂O₃^{? ?} anion. The [Ph₄As]⁺ salt of the dinuclear complex anion is triclinic, space group P1 , a = 11.226(6), b = 12.423(6), c = 19.000(10) Å, β = 76.47°(4), β = 83.98°(4), γ = 84.71°(4), Z = 2. In all these compounds the coordination of Cu^I is trigonal-planar, the S₃N^? chelate group coordinates the Cu in the usual way by two S atoms.     

The Decomposition of Aqueous Dithionite and its reactions with polythionates SnO2−6 (n = 3–5) studied by ion-pair chromatography

Aqueous dithionite decomposes at 20°C and pH values not far from 7.0 to give thiosulfate and sulfite from which trithionate may form. Addition of thiosulfate accelerates this reaction only at pH < 6. The pH dependence is explained by formation of HS₂O₃^? ions which are reduced by dithionite to HS^? and SO^2?₃. Sulfide destroys dithionite by nucleophilic cleavage, probably with formation of sulfoxylate and thiosulfite ions. The polythionates S_nO^2?₆ (n = 3–5) are reduced by dithionite at pH = 7.0 and 20°C according to S_nO^2?₆ + S₂O^2?₄ + 2 H₂O→S₂O₃^2? + S_n–3SO₃^2? + 4H¹ + 2SO₃^2? The reaction rate rapidly increases with the number n of sulfur atoms. In secondary reactions sulfite attacks S_nO₆^2? ions with thiosulfate formation.     

S4N3⊕[ReCl4(NSCl)2]⊖ Synthese und Kristallstruktur

S₄N₃^⊕[ReCl₄(NSCl)₂]^?. Synthesis and Crystal Structure S₄N₃^⊕[ReCl₄(NSCl)₂]^? is formed as a byproduct in the reaction of Re₂(CO)₁₀ with excess trithiazyl chloride. The compound is characterized by a crystal structure analysis by X-ray methods. S₄N₃[ReCl₄(NSCl)₂] crystallizes in the noncentrosymmetric space group P2₁2₁2₁ with four formula units per unit cell and the lattice dimensions a = 980, b = 1205, c = 1362 pm (2376 observed, independent reflexions; R = 0.076). The compound consists of the well known cyclic planar S₄N₃^⊕-cations and anions [ReCl₄(NSCl)₂]^?, in which the rhenium atom is coordinated octahedral by four Cl atoms and two cis-positioned NSCl ligands. The mean Re? N and N? S bond lengths (177 pm and 158 pm) correspond to double bonds. The bond lengths and angles are much like in the structure of AsPh₄[ReCl₄(NSCl)₂]; however the chlorine atoms of the NSCl ligands are turned to each other.     

Efficient Noble‐Metal‐Free γ‐Fe2O3@NiO Core–Shell Nanostructured Photocatalysts for Water Oxidation

Flowerlike noble‐metal‐free γ‐Fe₂O₃@NiO core–shell hierarchical nanostructures have been fabricated and examined as a catalyst in the photocatalytic oxidation of water with [Ru(bpy)₃](ClO₄)₂ as a photosensitizer and Na₂S₂O₈ as a sacrificial electron acceptor. An apparent TOF of 0.29 μmols^?1 m^?2 and oxygen yield of 51 % were obtained with γ‐Fe₂O₃@NiO. The γ‐Fe₂O₃@NiO core–shell hierarchical nanostructures could be easily separated from the reaction solution whilst maintaining excellent water‐oxidation activity in the fourth and fifth runs. The surface conditions of γ‐Fe₂O₃@NiO also remained unchanged after the photocatalytic reaction, as confirmed by X‐ray photoelectron spectroscopy (XPS).     

Kinetics and Mechanism of Oxidation of S2O32− by a Co‐Bound μ‐Amido‐μ‐Superoxo Complex

In acetate buffer media (pH 4.5–5.4) thiosulfate ion (S₂O₃^2?) reduces the bridged superoxo complex, [(NH₃)₄Co^III(μ‐NH₂,μ‐O₂)Co^III(NH₃)₄]⁴⁺ ( 1 ) to its corresponding μ‐peroxo product, [(NH₃)₄Co^III(μ‐NH₂,μ‐O₂)Co^III(NH₃)₄]³⁺ ( 2 ) and along a parallel reaction path, simultaneously S₂O₃^2? reacts with 1 to produce the substituted μ‐thiosulfato‐μ‐superoxo complex, [(NH₃)₄Co^III(μ‐S₂O₃,μ‐O₂)Co^III(NH₃)₄]³⁺ ( 3 ). The formation of μ‐thiosulfato‐μ‐superoxo complex ( 3 ) appears as a precipitate which on being subjected to FTIR shows absorption peaks that support the presence of Co(III)‐bound S‐coordinated S₂O₃^2? group. In reaction media, 3 readily dissolves to further react with S₂O₃^2? to produce μ‐thiosulfato‐μ‐peroxo product, [(NH₃)₄Co^III(μ‐S₂O₃,μ‐O₂)Co^III(NH₃)₄]²⁺ ( 4 ). The observed rate (k₀) increases with an increase in [T_Thio] ([T_Thio] is the analytical concentration of S₂O₃^2?) and temperature (T), but it decreases with an increase in [H⁺] and the ionic strength (I). Analysis of the log A_t versus time data (A is the absorbance of 1 at time t) reveals that overall the reaction follows a biphasic consecutive reaction path with rate constants k₁ and k₂ and the change of absorbance is equal to {a₁ exp(–k₁t) + a₂ exp(–k₂t)}, where k₁ > k₂.     

High-pressure range of the recombination O + O2 → O3

The recombination reaction O + O₂ → O₃ was studied by laser flash photolysis of pure O₂ in the pressure range 3–20 atm, and of N₂O? O₂ mixtures in the bath gases Ar, N₂, (CO₂, and SF₆) in the pressure range 3–200 atm. Fall-off curves of the reaction have been derived. Low-pressure rate coefficients were found to agree well with literature data. A high-pressure rate coefficient of k_∞ = (2.8 ± 1.0) × 10^?12 cm³ molecule^?1 s^?1 was obtained by extrapolation.     

Bis[μ3‐cis‐N‐(2‐aminopropyl)‐N′‐(2‐carboxylatophenyl)oxamidato(3–)]bis(2,2′‐bipyridine)dichloridotetracopper(II) dihydrate

The title complex, bis[μ₃‐cis‐N‐(2‐aminopropyl)‐N′‐(2‐carboxylatophenyl)oxamidato(3−)]‐1:2:4κ⁷N,N′,N′′,O:O′,O′′:O′′′;2:3:4κ⁷O′′′:N,N′,N′′,O:O′,O′′‐bis(2,2′‐bipyridine)‐2κ²N,N′;4κ²N,N′‐dichlorido‐1κCl,3κCl‐tetracopper(II) dihydrate, [Cu₄(C₁₂H₁₂N₃O₄)₂Cl₂(C₁₀H₈N₂)₂]·2H₂O, consists of a neutral cyclic tetracopper(II) system having an embedded centre of inversion and two solvent water molecules. The coordination of each Cu^II atom is square‐pyramidal. The separations of Cu^II atoms bridged by cis‐N‐(2‐aminopropyl)‐N′‐(2‐carboxylatophenyl)oxamidate(3−) and carboxyl groups are 5.2096 (4) and 5.1961 (5) Å, respectively. A three‐dimensional supramolecular structure involving hydrogen bonding and aromatic stacking is observed.     

Three novel topologically different metal–organic frameworks built from 3‐nitro‐4‐(pyridin‐4‐yl)benzoic acid

The design and synthesis of metal–organic frameworks (MOFs) have attracted much interest due to the intriguing diversity of their architectures and topologies. However, building MOFs with different topological structures from the same ligand is still a challenge. Using 3‐nitro‐4‐(pyridin‐4‐yl)benzoic acid (HL) as a new ligand, three novel MOFs, namely poly[[(N,N‐dimethylformamide‐κO)bis[μ₂‐3‐nitro‐4‐(pyridin‐4‐yl)benzoato‐κ³O,O′:N]cadmium(II)] N,N‐dimethylformamide monosolvate methanol monosolvate], {[Cd(C₁₂H₇N₂O₄)₂(C₃H₇NO)]·C₃H₇NO·CH₃OH}_n, ( 1 ), poly[[(μ₂‐acetato‐κ²O:O′)[μ₃‐3‐nitro‐4‐(pyridin‐4‐yl)benzoato‐κ³O:O′:N]bis[μ₃‐3‐nitro‐4‐(pyridin‐4‐yl)benzoato‐κ⁴O,O′:O′:N]dicadmium(II)] N,N‐dimethylacetamide disolvate monohydrate], {[Cd₂(C₁₂H₇N₂O₄)₃(CH₃CO₂)]·2C₄H₉NO·H₂O}_n, ( 2 ), and catena‐poly[[[diaquanickel(II)]‐bis[μ₂‐3‐nitro‐4‐(pyridin‐4‐yl)benzoato‐κ²O:N]] N,N‐dimethylacetamide disolvate], {[Ni(C₁₂H₇N₂O₄)₂(H₂O)₂]·2C₄H₉NO}_n, ( 3 ), have been prepared. Single‐crystal structure analysis shows that the Cd^II atom in MOF ( 1 ) has a distorted pentagonal bipyramidal [CdN₂O₅] coordination geometry. The [CdN₂O₅] units as 4‐connected nodes are interconnected by L^? ligands to form a fourfold interpenetrating three‐dimensional (3D) framework with a dia topology. In MOF ( 2 ), there are two crystallographically different Cd^II ions showing a distorted pentagonal bipyramidal [CdNO₆] and a distorted octahedral [CdN₂O₄] coordination geometry, respectively. Two Cd^II ions are connected by three carboxylate groups to form a binuclear [Cd₂(COO)₃] cluster. Each binuclear cluster as a 6‐connected node is further linked by acetate groups and L^? ligands to produce a non‐interpenetrating 3D framework with a pcu topology. MOF ( 3 ) contains two crystallographically distinct Ni^II ions on special positions. Each Ni^II ion adopts an elongated octahedral [NiN₂O₄] geometry. Each Ni^II ion as a 4‐connected node is linked by L^? ligands to generate a two‐dimensional network with an sql topology, which is further stabilized by two types of intermolecular OW—HW…O hydrogen bonds to form a 3D supramolecular framework. MOFs ( 1 )–( 3 ) were also characterized by powder X‐ray diffraction, IR spectroscopy and thermogravimetic analysis. Furthermore, the solid‐state photoluminescence of HL and MOFs ( 1 ) and ( 2 ) have been investigated. The photoluminescence of MOFs ( 1 ) and ( 2 ) are enhanced and red‐shifted with respect to free HL. The gas adsorption investigation of MOF ( 2 ) indicates a good separation selectivity (71) of CO₂/N₂ at 273 K (i.e. the amount of CO₂ adsorption is 71 times higher than N₂ at the same pressure).     

catena‐Poly[potassium [copper(II)‐μ‐isothiocyanato‐μ‐N‐salicylidene‐β‐alaninato(2–)]]

The title polymeric compound, catena‐poly­[dipotassium [bis­[μ‐N‐salicyl­idene‐β‐alaninato(2−)]‐κ⁴O,N,O′:O′′;κ⁴O′′:O,N,O′‐dicopper(II)]‐di‐μ‐iso­thio­cyanato‐κ²N:S;κ²S:N], {K[Cu(NCS)(C₁₀H₉NO₃)]}_n, consists of [iso­thio­cyanato(N‐salicyl­idene‐β‐alaninato)copper(II)]⁻ anions connected through the two three‐atom thio­cyanate (μ‐NCS) and the two anti,anti‐μ‐­carboxyl­ate bridges into infinite one‐dimensional polymeric anions, with coulombically interacting K⁺ counter‐ions with coordination number 7 constrained between the chains. The Cu^II atoms adopt a distorted tetragonal–bipyramidal coordination, with three donor atoms of the tridentate Schiff base and one N atom of the bridging μ‐NCS ligand in the basal plane. The first axial position is occupied by a thio­cyanate S atom of a symmetry‐related μ‐NCS ligand at an apical distance of 2.9770 (8) Å, and the second position is occupied by an O atom of a bridging carboxyl­ate group from an adjacent coordination unit at a distance of 2.639 (2) Å.     

Controllable assembly of a three‐dimensional metal–organic supramolecular framework displaying hydrogen‐bonding and π–π stacking interactions

The complex poly[[aqua(μ₂‐phthalato‐κ²O¹:O²){μ₃‐2‐[3‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl]acetato‐κ⁴N²,N³:O:O′}{μ₂‐2‐[3‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl]acetato‐κ³N²,N³:O}dizinc(II)] dihydrate], {[Zn₂(C₁₀H₈N₃O₂)₂(C₈H₄O₄)(H₂O)]·2H₂O}_n, has been prepared by solvothermal reaction of 2‐[3‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl]acetonitrile (PPAN) with zinc(II). Under hydrothermal conditions, PPAN is hydrolyzed to 2‐[3‐(pyridin‐2‐yl)‐1H‐pyrazol‐1‐yl]acetate (PPAA⁻). The structure determination reveals that the complex is a one‐dimensional double chain containing cationic [Zn₄(PPAA)₄]⁴⁺ structural units, which are further extended by bridging phthalate ligands. The one‐dimensional chains are extended into a three‐dimensional supramolecular architecture via hydrogen‐bonding and π–π stacking interactions.     

FeIII in a low‐spin state in caesium bis[3‐ethoxysalicylaldehyde 4‐methylthiosemicarbazonato(2–)‐κ3O2,N1,S]ferrate(III) methanol monosolvate

The synthesis and crystal structure (at 100 K) of the title compound, Cs[Fe(C₁₁H₁₃N₃O₂S₂)₂]·CH₃OH, is reported. The asymmetric unit consists of an octahedral [Fe^III(L)₂]⁻ fragment, where L²⁻ is 3‐ethoxysalicylaldehyde 4‐methylthiosemicarbazonate(2−) {systematic name: [2‐(3‐ethoxy‐2‐oxidobenzylidene)hydrazin‐1‐ylidene](methylamino)methanethiolate}, a caesium cation and a methanol solvent molecule. Each L²⁻ ligand binds through the thiolate S, the imine N and the phenolate O atoms as donors, resulting in an Fe^IIIS₂N₂O₂ chromophore. The O,N,S‐coordinating ligands are orientated in two perpendicular planes, with the O and S atoms in cis positions and the N atoms in trans positions. The Fe^III cation is in the low‐spin state at 100 K.     

Mechanism of nucleophilic substitution in chromium(III) complexes. III. formation of Azidopentamminechromium(III) ion from aquopentamminechromium(III) ion in NaN3–HN3 buffer media

The kinetics of formation of [Cr(NH₃)₅N₃]²⁺ in the reaction of [Cr(NH₃)₅(OH₂)³⁺] in NaN₃–HN₃ buffer media (pH ca. 3.4–4.3) has been studied spectrophotometrically under different conditions for elucidation of reaction mechanism. The reaction occurs in two concurrent paths involving reactions of the aquo complex and its conjugate base (the hydroxo complex) with azide ion (gross rate constants k₁ and k₂ respectively). Results, including values of the activation parameters (ΔH≠ and ΔS≠) are in agreement with S_N1 IP mechanism for both the paths. The observed relativ nucleophilicityo of N₃^? compared to that reported in literature for Cl^? and NCS^? is N > NCS^? > Cl^?.     

Ion–molecule reaction in the gas phase 3—nucleophilic substitution of 17ξ-R-5α,14β-androstane-14,17ξ-diols under [NH4]+ chemical ionization conditions1

Under Ammonia chemical Ionization conditions the source decompositions of [M + NH₄]⁺ ions formed from epimeric tertiary steroid alchols 14 OH_β, 17OH_α or 17 OH_β substituted at position 17 have been studied. They give rise to formation of [M + NH₄? H₂O]⁺ dentoed as [MH_sH]⁺, [M_sH? H₂O]⁺, [M_sH? NH₃]⁺ and [M_sH? NH₃? H₂O]⁺ ions. Stereochemical effects are observed in the ratios [M_sH? H₂O]⁺/[M_sH? NH₃]⁺. These effects are significant among metastable ions. In particular, only the [M_sH]⁺ ions produced from trans-diol isomers lose a water molecule. The favoured loss of water can be accounted for by an S_N2 mechanism in which the insertion of NH₃ gives [M_sH]⁺ with Walden inversion occurring during the ion-molecule reaction between [M + NH₄]⁺ + NH₃. The S_N1 and S_Ni pathways have been rejected.     

A one‐dimensional CdII coordination polymer constructed from 4‐(dimethylamino)pyridinium‐1‐acetate ligands and thiocyanate coordination bridges

A new cadmium–thiocyanate complex, namely catena‐poly[1‐carboxymethyl‐4‐(dimethylamino)pyridinium [cadmium(II)‐tri‐μ‐thiocyanato‐κ⁴N:S;κ²S:N] [[[4‐(dimethylamino)pyridinium‐1‐acetate‐κ²O,O′]cadmium(II)]‐di‐μ‐thiocyanato‐κ²N:S;κ²S:N]], {(C₉H₁₃N₂O₂)[Cd(NCS)₃][Cd(NCS)₂(C₉H₁₂N₂O₂)]}_n, was synthesized by the reaction of 4‐(dimethylamino)pyridinium‐1‐acetate, cadmium nitrate tetrahydrate and potassium thiocyanide in aqueous solution. In the crystal structure, two types of Cd^II atoms are observed in distorted octahedral coordination environments. One type of Cd^II atom is coordinated by two O atoms from the carboxylate group of the 4‐(dimethylamino)pyridinium‐1‐acetate ligand and by two N atoms and two S atoms from four different thiocyanate ligands, while the second type of Cd^II atom is coordinated by three N atoms and three S atoms from six different thiocyanate ligands. Neighbouring Cd^II atoms are linked by thiocyanate bridges to form a one‐dimensional zigzag chain and a one‐dimensional coordination polymer. Hydrogen‐bond interactions are involved in the formation of the supramolecular network.     

Two salts of 5‐sulfosalicylic acid and 3‐aminopyridine

5‐Sulfosalicylic acid (5‐SSA) and 3‐aminopyridine (3‐APy) crystallize in the same solvent system, resulting in two kinds of 1:1 proton‐transfer organic adduct, namely 3‐aminopyridinium 3‐carboxy‐4‐hydroxybenzenesulfonate monohydrate, C₅H₇N₂⁺·C₇H₅O₆S⁻·H₂O or 3‐APy·5‐SSA·H₂O, (I), and the anhydrous adduct, C₅H₇N₂⁺·C₇H₅O₆S⁻ or 3‐APy·5‐SSA, (II). Both compounds have extensively hydrogen‐bonded three‐dimensional layered polymer structures, with interlayer homo‐ and heterogeneous π–π interactions in (I) and (II), respectively.     

Three‐dimensional networks in 5‐methylimidazolium 3‐carboxy‐4‐hydroxybenzenesulfonate and bis(5‐methylimidazolium) 3‐carboxylato‐4‐hydroxybenzenesulfonate

The two title proton‐transfer compounds, 5‐methylimidazolium 3‐carboxy‐4‐hydroxybenzenesulfonate, C₄H₇N₂⁺·C₇H₅O₆S⁻, (I), and bis(5‐methylimidazolium) 3‐carboxylato‐4‐hydroxybenzenesulfonate, 2C₄H₇N₂⁺·C₇H₅O₆S²⁻, (II), are each organized into a three‐dimensional network by a combination of X—H...O (X = O, N or C) hydrogen bonds, and π–π and C—H...π interactions.     

20‐Di­cyano­methyl­ene‐5,8,11,14‐tetraoxa‐2,17‐di­thia­bi­cyclo­[16.4.1]­tricosa‐1(23),18,21‐triene and its mercury(II) dichloride complex

The structures of the title compound, C₂₀H₂₄N₂O₄S₂, and its mercury(II) dichloride complex, dichloro{20‐di­cyano­methyl­ene‐5,8,11,14‐tetraoxa‐2,17‐di­thia­bi­cyclo­[16.4.1]­tricosa‐1(23),18,­21‐tri­ene‐κ⁴O,κS¹⁷}mercury(II), [HgCl₂(C₂₀­H₂₄­N₂­O₄­S₂)], have been determined by X‐ray crystallographic analyses. The mercury(II) dichloride complex has two independent mol­ecules of [HgCl₂(C₂₀H₂₄N₂O₄S₂)] in the lattice. The mercury(II) ion has pentagonal bipyramidal coordination which involves one S atom, four O atoms and two Cl^? ions.     

SN1‐SN2 and SN2‐SN3 mechanistic changes revealed by transition states of the hydrolyses of benzyl chlorides and benzenesulfonyl chlorides

Hydrolysis reactions of benzyl chlorides and benzenesulfonyl chlorides were theoretically investigated with the density functional theory method, where the water molecules are explicitly considered. For the hydrolysis of benzyl chlorides (para‐Z? C₆H₄? CH₂? Cl), the number of water molecules (n) slightly influences the transition‐state (TS) structure. However, the para‐substituent (Z) of the phenyl group significantly changes the reaction process from the stepwise (S_N1) to the concerted (S_N2) pathway when it changes from the typical electron‐donating group (EDG) to the typical electron‐withdrawing one (EWG). The EDG stabilizes the carbocation (MeO? C₆H₄? CH₂⁺), which in turn makes the S_N1 mechanism more favorable and vice versa. For the hydrolysis of benzenesulfonyl chlorides (para‐Z? C₆H₄? SO₂? Cl), both the Z group and n influence the TS structure. For the combination of the large n value (n > 9) and EDG, the S_N2 mechanism was preferred. Conversely, for the combination of the small n value and EWG, the S_N3 one was more favorable. © 2014 Wiley Periodicals, Inc.