Synthesis of the Active Stilbenoids by Photooxidation Reaction of trans-ε-Viniferin

Two new stilbenoids, cis‐?‐viniferin (3) and 2b, 14b‐dehydro‐bisresveratrol (4) were synthesized by photooxidation reaction of trans‐?‐viniferin (2) prepared from tram‐resveratrol (1). Pentamethoxyl trans‐?‐viniferin (5) and pentamethoxyl cis‐?‐viniferin (6) were also obtained by methylation of trans‐?‐viniferin (2) with (MeO)₂SO₂. Their structures were elucidated on the basis of spectral evidence. Compounds 3 and 4 showed potent inhibition of TNF‐α at concentrations of 10^?‐⁵ mol.L^?1 with inhibitory ratios of 51.43% and 36.64%. respectively.     

Functional carbo‐Butadienes: Nonaromatic Conjugation Effects through a 14‐Carbon, 24‐π‐Electron Backbone

A systematic study of carbo‐butadiene motifs not embedded in an aromatic carbo‐benzene ring is described. Dibutatrienylacetylene (DBA) targets R¹?C(R)?C?C?C(Ph)?C≡C?C(Ph)?C?C?C(R)?R² are devised, in which R is C≡CSiiPr₃ and R¹ and R² are R, H, or 4‐X‐C₆H₄, with the latter including three known representatives (X: H, NMe₂, or NH₂). The synthesis method is based on the SnCl₂‐mediated reduction of pentaynediols prepared by early or late divergent strategies; the latter allows access to a OMe–NO₂ push–pull diaryl‐DBA. If R¹ and R² are H, an over‐reduced dialkynylbutatriene (DAB) with two allenyl caps was isolated instead of the unsubstituted DBA. If R¹=R²=R, the tetraalkynyl‐DBA target was obtained, along with an over‐reduced DBA product with a 12‐membered 1,2‐alkylidene‐1H₂,2H₂‐carbo‐cyclobutadiene ring. X‐ray crystallography shows that all of the acyclic DBAs adopt a planar trans–transoid–trans configuration. The maximum UV/Vis absorption wavelength is found to vary consistently with the overall π‐conjugation extent and, more intriguingly, with the π‐donor character of the aryl X substituents, which varies consistently with the first (reversible) reduction potential and first (irreversible) oxidation peak, as determined by voltammetry.     

Mechanistic Insights into an Unexpected Carbon Dioxide Insertion Reaction through the Crystal Structures of Carbamic Diphenylthiophosphinic Anhydride and l‐[(4‐Nitrophenyl)‐sulfonyl]‐trans‐2,5‐pyrrolidinedicarboxylic Acid Methyl Ester

The crystal structures of an unexpected carbon dioxide inserted carbamidiphenylthiophosphinic anhydride and l‐[(4‐nitrophenyl) sulfonyl]‐trans‐2, 5‐pyrrolidinedicarboxylic acid methyl ester were determined by X‐ray analysis. They crystallized in the space group P2₁(#4) with a =0.9550(2), b = 0.9401(4), c= 1.2880(2) nm, β= 107.74°, V= 1.1013 (5) nm³, D_caled= 1.349 g/cm³, Z = 2 and P2₁2₁2₁(# 19) with a = 1.4666(2), b = 0.7195(2), c = 1.6339(2) nm, V = 1.7240(7) nm³, D_caled = 1.434 g/cm³, Z = 4, respectively. Through the investigation of these two crystal structures, the mechanistic insights into this unexpected carbon dioxide insertion in the reaction of trans‐2,5‐disubstituted pyrrolidine with diphenylthiophosphoryl chloride in the presence of potassium carbonate were disclosed.     

A novel azocompound, 2‐(4‐phenylazoaniline)‐4‐phenylphenol: Spectroscopic and quantum‐chemical approach

A novel azocompound with two nonequivalents azo groups, 2‐(4‐phenylazoaniline)‐4‐phenylphenol, was synthesized and characterized by spectroscopic and computational analysis. An intramolecular hydrogen bonding (HB), ? O₁? H₁ ··· N₁? , involving the ? N₁?N₂? group and the proton in a neighbor hydroxyl moiety, was identified. It was found responsible for a characteristic π‐conjugated H₁? O₁? C₁₈?C₁₃? N₂?N₁? six‐membered cyclic fragment. It is worth noting that this azo group is involved in an azo‐hydrazo equilibrium, being the azo form the most stable one. This resonance‐assisted HB was characterized using the OH‐related infrared bands and the corresponding signals in ¹H NMR. In addition, conformational studies and geometrical and electronic parameter calculations were performed using the density functional theory, at B3LYP/6‐311++G** level. Bond and ring critical points were identified using the atoms in molecules theory, which allowed confirming the intramolecular HB. The second azo‐group cannot be involved in HB, but it also presents two stereoisomerics forms corresponding to cis (Z) and trans (E) configurations, with the later being the one with the lowest energy. © 2013 Wiley Periodicals, Inc.     

Dihalodimethyltin(IV) complexes of 2‐(pyrazol‐1‐ylmethyl)pyridine

Reaction of dichloro‐ and dibromodimethyltin(IV) with 2‐(pyrazol‐1‐ylmethyl)pyridine (PMP) afforded [SnMe₂Cl₂(PMP)] and [SnMe₂Br₂(PMP)] respectively. The new complexes were characterized by elemental analysis and mass spectrometry and by IR, Raman and NMR (¹H, ¹³C) spectroscopies. Structural studies by X‐ray diffraction techniques show that the compounds consist of discrete units with the tin atom octahedrally coordinated to the carbon atoms of the two methyl groups in a trans disposition (Sn? C = 2.097(5), 2.120(5) Å and 2.110(6), 2.121(6) Å in the chloro and in the bromo compounds respectively), two cis halogen atoms (Sn? Cl = 2.4908(16), 2.5447(17) Å; Sn? Br = 2.6875(11), 2.7464(9) Å) and the two donor atoms of the ligand (Sn? N = 2.407(4), 2.471(4) Å and 2.360(5), 2.455(5) Å). In both cases, the Sn? N(pyridine) bond length is markedly longer than the Sn? N(pyrazole) distance. Copyright © 2003 John Wiley & Sons, Ltd.     

Synthesis and Spectroscopic Characterization of Potassium Polyfluoroalken‐1‐yltrifluoroborates

The potassium fluoroborates K[RCF=CFBF₃] (R = F, Cl (cis‐/trans‐mixture), trans‐C₄F₉, cis‐C₂F₅, cis‐C₆F₁₃, trans‐C₄H₉, trans‐C₆H₅) were prepared by fluoridation (methoxide‐fluoride substitution with K[HF₂]) of RCF=CFB(OMe)₂ and Li[RCF=CFB(OMe)₃] which were obtained from RCF=CFLi and B(OMe)₃. The K[RCF=CFBF₃] salts were characterized by their ¹H, ¹¹B, ¹⁹F NMR and IR spectra.     

Potassium hydrogen trans‐glutaconate monohydrate at 295, 245 and 40 K,and its rubidium analogue at 298 K

A centrosymmetric and short O—H?O hydrogen bond was found in isomorphic crystals of potassium hydrogen trans‐glutaconate monohydrate (potassium hydrogen trans‐pent‐2‐ene‐1,5‐dioate, K⁺·C₅H₅O₄^?·H₂O), (I), and rubidium hydrogen trans‐glutaconate monohydrate (rubidium hydrogen trans‐pent‐2‐ene‐1,5‐dioate, Rb⁺·C₅H₅O₄^?·H₂O), (II). The O?O distance at room temperature is 2.444 (3) Å in (I), and 2.417 (4) Å in (II). The O?O distance for (I) showed no significant decrease at low temperatures.     

A novel two‐dimensional cadmium(II) complex: poly[diaquatris(μ4‐cyclohexane‐1,4‐dicarboxylato)bis[2‐(pyridin‐4‐yl)‐1H‐benzimidazole]tricadmium(II)

The title compound, [Cd₃(C₈H₁₀O₄)₃(C₁₂H₉N₃)₂(H₂O)₂]_n or [Cd₃(chdc)₃(4‐PyBIm)₂(H₂O)₂]_n, was synthesized hydrothermally from the reaction of Cd(CH₃COO)₂·2H₂O with 2‐(pyridin‐4‐yl)‐1H‐benzimidazole (4‐PyBIm) and cyclohexane‐1,4‐dicarboxylic acid (1,4‐chdcH₂). The asymmetric unit consists of one and a half Cd^II cations, one 4‐PyBIm ligand, one and a half 1,4‐chdc²⁻ ligands and one coordinated water molecule. The central Cd^II cation, located on an inversion centre, is coordinated by six carboxylate O atoms from six 1,4‐chdc²⁻ ligands to complete an elongated octahedral coordination geometry. The two terminal rotationally symmetric Cd^II cations each exhibits a distorted pentagonal–bipyramidal geometry, coordinated by one N atom from 4‐PyBIm, five O atoms from three 1,4‐chdc²⁻ ligands and one O atom from an aqua ligand. The 1,4‐chdc²⁻ ligands possess two conformations, i.e.e,e‐trans‐chdc²⁻ and e,a‐cis‐chdc²⁻. The cis‐1,4‐chdc²⁻ ligands bridge the Cd^II cations to form a trinuclear {Cd₃}‐based chain along the b axis, while the trans‐1,4‐chdc²⁻ ligands further link adjacent one‐dimensional chains to construct an interesting two‐dimensional network.     

Four‐Center Oxidation State Combinations and Near‐Infrared Absorption in [Ru(pap)(Q)2]n (Q=3,5‐Di‐tert‐butyl‐N‐aryl‐1,2‐benzoquinonemonoimine,pap=2‐Phenylazopyridine)

The complex series [Ru(pap)(Q)₂]ⁿ ([ 1 ]ⁿ–[ 4 ]ⁿ; n=+2, +1, 0, ?1, ?2) contains four redox non‐innocent entities: one ruthenium ion, 2‐phenylazopyridine (pap), and two o‐iminoquinone moieties, Q=3,5‐di‐tert‐butyl‐N‐aryl‐1,2‐benzoquinonemonoimine (aryl=C₆H₅ ( 1⁺ ); m‐(Cl)₂C₆H₃ ( 2⁺ ); m‐(OCH₃)₂C₆H₃ ( 3⁺ ); m‐(tBu)₂C₆H₃ ( 4 ⁺)). A crystal structure determination of the representative compound, [ 1 ]ClO₄, established the crystallization of the ctt‐isomeric form, that is, cis and trans with respect to the mutual orientations of O and N donors of two Q ligands, and the coordinating azo N atom trans to the O donor of Q. The sensitive C? O (average: 1.299(3) Å), C? N (average: 1.346(4) Å) and intra‐ring C? C (meta; average: 1.373(4) Å) bond lengths of the coordinated iminoquinone moieties in corroboration with the N?N length (1.292(3) Å) of pap in 1 ⁺ establish [Ru^III(pap⁰)(Q^.?)₂]⁺ as the most appropriate electronic structural form. The coupling of three spins from one low‐spin ruthenium(III) (t_2g⁵) and two Q^.? radicals in 1 ⁺– 4 ⁺ gives a ground state with one unpaired electron on Q^.?, as evident from g=1.995 radical‐type EPR signals for 1 ⁺– 4 ⁺. Accordingly, the DFT‐calculated Mulliken spin densities of 1 ⁺ (1.152 for two Q, Ru: ?0.179, pap: 0.031) confirm Q‐based spin. Complex ions 1 ⁺– 4 ⁺ exhibit two near‐IR absorption bands at about λ=2000 and 920 nm in addition to intense multiple transitions covering the visible to UV regions; compounds [ 1 ]ClO₄–[ 4 ]ClO₄ undergo one oxidation and three separate reduction processes within ±2.0 V versus SCE. The crystal structure of the neutral (one‐electron reduced) state ( 2 ) was determined to show metal‐based reduction and an EPR signal at g=1.996. The electronic transitions of the complexes 1 ⁿ– 4 ⁿ (n=+2, +1, 0, ?1, ?2) in the UV, visible, and NIR regions, as determined by using spectroelectrochemistry, have been analyzed by TD‐DFT calculations and reveal significant low‐energy absorbance (λ_max>1000 nm) for cations, anions, and neutral forms. The experimental studies in combination with DFT calculations suggest the dominant valence configurations of 1 ⁿ– 4 ⁿ in the accessible redox states to be [Ru^III(pap⁰)(Q^.?)(Q⁰)]²⁺ ( 1 ²⁺– 4 ²⁺)→[Ru^III(pap⁰)(Q^.?)₂]⁺ ( 1 ⁺– 4 ⁺)→[Ru^II(pap⁰)(Q^.?)₂] ( 1 – 4 )→[Ru^II(pap^.?)(Q^.?)₂]^? ( 1 ^?– 4 ^?)→[Ru^III(pap^.?)(Q^2?)₂]^2? ( 1 ^2?– 4 ^2?).     

Synthesis of Some New 2‐Oxo‐N‐[(10H‐phenothiazin‐10‐yl)alkyl] Derivatives of Azetidine‐1‐carboxamides

The synthesis of a new series of 4‐aryl‐3‐chloro‐2‐oxo‐N‐[3‐(10H‐phenothiazin‐10‐yl)propyl]azetidine‐1‐carboxamides, 4a – 4m , is described. Phenothiazine on reaction with Cl(CH₂)₃Br at room temperature gave 10‐(3‐chloropropyl)‐10H‐phenothiazine ( 1 ), and the latter reacted with urea to yield 1‐[3‐(10H‐phenothiazin‐10‐yl)propyl]urea ( 2 ). Further reaction of 2 with several substituted aromatic aldehydes led to N‐(arylmethylidene)‐N′‐[3‐(phenothiazin‐10‐yl)propyl]ureas 3a – 3m , which, on treatment with ClCH₂COCl in the presence of Et₃N, furnished the desired racemic trans‐2‐oxoazetidin‐1‐carboxamide derivatives 4a – 4m . The structures of all new compounds were confirmed by IR, and ¹H‐ and ¹³C‐NMR spectroscopy, FAB mass spectrometry, and chemical methods.     

Construction and photocatalytic properties of two metal‐mediated coordination polymers based on benzene‐1,3,5‐tricarboxylic acid and trans‐1‐(pyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene

With the rapid development of modern industry, water pollution has become an intractable environmental issue facing humans worldwide. In particular, the organic dyes discharged into natural water from dyestuffs, dyeing and the textile industry are the main sources of pollution in wastewater. To eliminate these types of pollutants, degradation of organic contaminants through a photocatalytic technique is an effective methodology. To exploit more crystalline photocatalysts for the degradation of organic dyes, two coordination polymers, namely catena‐poly[[(3,5‐dicarboxybenzene‐1‐carboxylato‐κO ¹)silver(I)]‐μ‐trans‐1‐(pyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene‐κ²N :N ′], [Ag(C₉H₅O₆)(C₁₂H₁₀N₂)]_n or [Ag(H₂BTC)(3,4′‐bpe)]_n , (I), and poly[[(μ₃‐5‐carboxybenzene‐1,3‐dicarboxylato‐κ⁴O ¹,O ^1′:O ³:O ³)[μ‐trans‐1‐(pyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene‐κ²N :N′ ]cadmium(II)] monohydrate], {[Cd(C₉H₄O₆)(C₁₂H₁₀N₂)]·H₂O}_n or {[Cd(HBTC)(3,4′‐bpe)]·H₂O}_n , (II), have been prepared by the hydrothermal reactions of benzene‐1,3,5‐tricarboxylic acid (H₃BTC) and trans‐1‐(pyridin‐3‐yl)‐2‐(pyridin‐4‐yl)ethene (3,4′‐bpe) in the presence of AgNO₃ or Cd(NO₃)₂·4H₂O, respectively. These two title compounds have been structurally characterized by IR spectroscopy, elemental analysis, single‐crystal X‐ray diffraction and powder X‐ray diffraction. In (I), the Ag^I ions and organic ligands form a one‐dimensional coordination chain, and adjacent coordination chains are connected by Ag…O interactions to give rise to a two‐dimensional supramolecular network. Each two‐dimensional network is entangled with other equivalent networks to generate an infrequent interlocked 2D→3D (2D and 3D are two‐ and three‐dimensional, respectively) supramolecular framework. In (II), the Cd^II ions are bridged by the HBTC²⁻ and 3,4′‐bpe ligands, which lie across centres of inversion, to give a two‐dimensional coordination network. The thermal stabilities and photocatalytic properties of the title compounds have also been studied.     

Synthesis and Structure of O,O‐Diethyl N‐[(trans‐4‐Aryl‐5,5‐dimethyl‐2‐oxido‐2λ5‐1,3,2‐dioxaphosphorinan‐2‐yl)methyl]phosphoramidothioates

A study on the synthesis of the novel N‐(cyclic phosphonate)‐substituted phosphoramidothioates, i.e., O,O‐diethyl N‐[(trans‐4‐aryl‐5,5‐dimethyl‐2‐oxido‐2λ⁵‐1,3,2‐dioxaphosphorinan‐2‐yl)methyl]phosphoramidothioates 4a – l , from O,O‐diethyl phosphoramidothioate ( 1 ), a benzaldehyde or ketone 2 , and a 1,3,2‐dioxaphosphorinane 2‐oxide 3 was carried out (Scheme 1 and Table 1). Some of their stereoisomers were isolated, and their structure was established. The presence of acetyl chloride was essential for this reaction and accelerated the process of intramolecular dehydration of intermediate 5 forming the corresponding Schiff base 7 (Scheme 2).     

Three Polymorphic CdII Coordination Polymers Obtained from the Solution and Mechanochemical Reactions of 3‐Cyanopentane‐2,4‐dione with CdII Acetate

We previously reported that monomeric and polymeric metal complexes are obtained from solution and mechanochemical reactions of 3‐cyano‐pentane‐2,4‐dione (CNacacH) with 3d metal acetates (M=Mn^II, Fe^II, Co^II, Ni^II, Cu^II, and Zn^II). A common feature found in all complexes was that their structural base is trans‐[M(CNacac)₂]. Here, we report that the reactions of CNacacH with Cd^II acetate in the solution and solid states afford different coordination polymers composed of trans‐[Cd(CNacac)₂] and cis‐[Cd(CNacac)₂] units, respectively. From a methanol solution containing CNacacH (L) and Cd(OAc)₂ ? 2 H₂O (M), a coordination polymer ( Cd‐1 ) in which trans‐[Cd(CNacac)₂] units are three‐dimensionally linked was obtained. In contrast, two different coordination polymers, Cd‐2 and Cd‐3 , were obtained from mechanochemical reactions of CNacacH with Cd(OAc)₂ ? 2 H₂O at M/L ratios of 1:1 and 1:2, respectively. In Cd‐2 , cis‐[Cd(CNacac)₂] units are two‐dimensionally linked, whereas the units are linked three‐dimensionally in Cd‐3 . Furthermore, Cd‐1 and Cd‐2 converted to Cd‐3 by applying an annealing treatment and grinding with a small amount of liquid, respectively, in spite of the polymeric structures. These phenomena, 1) different structures are formed from solution and mechanochemical reactions, 2) two polymorphs are formed depending on the M/L ratio, and 3) structural transformation of resulting polymeric structures, indicate the usability of mechanochemical method in the syntheses of coordination polymers as well as the peculiar structural flexibility of cadmium‐CNacac polymers.     

Synthesis, Crystal Structure of Ruthenium 1,2－Naphthoquinone－1－oxime Complex and Its Mediated C－－C Coupling Reactions of Ter－minal Alkynes

Substituted decarbonylation reaction of ruthenium 1,2‐naphthoquinone‐1‐oxime (1‐nqo) complex, cis‐, cis‐[Ru| ζ²‐N(O)C₁₀‐H₆O|₂(CO)₂] (1), with acetonitrile gave cis‐, cis‐[Ru | ζ²‐ N(O)C₁₀H₆O|₂(CO)(NCMe)] (2). Complex 2 was fully characterized by ¹H NMR, FAB MS, IR spectra and single crystal X‐ray analysis. Complex 2 maintains the coordination structure of 1 with the two naphthoquinonic oxygen atoms, as well as the two oximato nitrogen atoms located cis to each other, showing that there is no ligand rearrangement of the 1‐nqo ligands during the substitution reaction. The carbonyl group originally trans to the naphthoquinonic oxygen in one 1‐nqo ligand is left in its original position [O(5)‐Ru‐C(1), 174.0(6)°], while the other one originally trans to the oximato group of the other 1‐nqo ligand is substituted by NCMe [N(1)‐Ru‐N(3), 170.6(6)°]. This shows that the carbonyl trans to oximato group is more labile than the one trans to naphthoquinonic O atom towards substitution. This is probably due to the comparatively stronger ± back bonding from ruthenium metal to the carbonyl group trans to naphthoquinonic O atom, than the one trans to oximato group, resulting in the comparatively weaker Ru–‐CO bond for the latter and consequently easier replacement of this carbonyl. Selected coupling of phenylacetylene mediated by 2 gave a single trans‐dimerization product 3, while 2 mediated coupling reaction of methyl propiolate produced three products: one trans‐dimerization product 4 and two cyclotrimeric products 5 and 6.     

[Ni(terpy)(H2O)]‐trans‐[Ni‐(μ‐CN)2‐(CN)2]n,a one‐dimensional linear tetra­cyano­nickelate chain

The one‐dimensional chain catena‐poly­[[aqua(2,2′:6′,2′′‐terpyridyl‐κ³N)­nickel(II)]‐μ‐cyano‐κ²N:C‐[bis­(cyano‐κC)nickelate(II)]‐μ‐cyano‐κ²C:N], [Ni(terpy)(H₂O)]‐trans‐[Ni‐μ‐(CN)₂‐(CN)₂]_n or [Ni₂­(CN)₄­(C₁₅H₁₁N₃)(H₂O)], consists of infinite linear chains along the crystallographic [10] direction. The chains are composed of two distinct types of nickel ions, paramagnetic octahedral [Ni(terpy)(H₂O)]²⁺ cations (with twofold crystallographic symmetry) and diamagnetic planar [Ni(CN)₄]^2? anions (with the Ni atom on an inversion center). The [Ni(CN)₄]^2? units act as bidentate ligands bridging through two trans cyano groups thus giving rise to a new example of a trans–trans chain among planar tetra­cyano­nickelate complexes. The coordination geometry of the planar nickel unit is typical of slightly distorted octahedral nickel(II) complexes, but for the [Ni(CN)₄]^2? units, the geometry deviates from a planar configuration due to steric interactions with the ter­pyridine ligands.     

A pipecolic acid (Pip)‐containing dipeptide,Boc‐d‐Ala‐l‐Pip‐NHiPr

The title dipeptide, 1‐(tert‐butoxy­carbonyl‐d ‐alanyl)‐N‐iso­propyl‐l ‐pipecol­amide or Boc‐d ‐Ala‐l ‐Pip‐NHⁱPr (H‐Pip‐OH is pipecolic acid or piperidine‐2‐carboxylic acid), C₁₇H₃₁N₃­O₄, with a d –l heterochiral sequence, adopts a type II′β‐­turn conformation, with all‐trans amide functions, where the C‐terminal amide NH group interacts with the Boc carbonyl O atom to form a classical i+3 i intramolecular hydrogen bond. The C^α substituent takes an axial position [H^α (Pip) equatorial] and the trans pipecolamide function is nearly planar.     

Difunctionalized {closo‐1‐CB11} Clusters: 1‐ and 2‐Amino‐12‐ethynylcarba‐closo‐dodecaborates

Carba‐closo‐dodecaborate anions with two functional groups have been synthesized via a simple two‐step procedure starting from monoamino‐functionalized {closo‐1‐CB₁₁} clusters. Iodination at the antipodal boron atom provided access to [1‐H₂N‐12‐I‐closo‐1‐CB₁₁H₁₀]^? ( 1 a ) and [2‐H₂N‐12‐I‐closo‐1‐CB₁₁H₁₀]^? ( 2 a ), which have been transformed into the anions [1‐H₂N‐12‐RC?C‐closo‐1‐CB₁₁H₁₀]^? (R=H ( 1 b ), Ph ( 1 c ), Et₃Si ( 1 d )) and [2‐H₂N‐12‐RC?C‐closo‐1‐CB₁₁H₁₀]^? (R=H ( 2 b ), Ph ( 2 c ), Et₃Si ( 2 d )) by microwave‐assisted Kumada‐type cross‐coupling reactions. The syntheses of the inner salts 1‐Me₃N‐12‐RC?C‐closo‐1‐CB₁₁H₁₀ (R=H ( 1 e ), Et₃Si ( 1 f )) and 2‐Me₃N‐12‐RC?C‐closo‐1‐CB₁₁H₁₀ (R=H ( 2 e ), Et₃Si ( 2 f )) are the first examples for a further derivatization of the new anions. All {closo‐1‐CB₁₁} clusters have been characterized by multinuclear NMR and vibrational spectroscopy as well as by mass spectrometry. The crystal structures of Cs 1 a , [Et₄N] 2 a , K 1 b , [Et₄N] 1 c , [Et₄N] 2 c , 1 e , and [Et₄N][1‐H₂N‐2‐F‐12‐I‐closo‐1‐CB₁₁H₉]?0.5 H₂O ([Et₄N ]4 a ?0.5 H₂O) have been determined. Experimental spectroscopic data and especially spectroscopic data and bond properties derived from DFT calculations provide some information on the importance of inductive and resonance‐type effects for the transfer of electronic effects through the {closo‐1‐CB₁₁} cage.     

Anion Effects on the Formation of Silver(I) Complexes with the Flexible Ligand 4,4′‐Bis(1,2,4‐triazol‐1‐ylmethyl)biphenyl

The reaction of 4,4′‐bis(1,2,4‐triazol‐1‐ylmethyl)biphenyl (btmb) with silver(I) salts of BF₄^–, NO₃^– and N₃^– led to the formation of four new silver(I) coordination polymers {[Ag(btmb)]BF₄}_n ( 1 ), {[Ag₂(btmb)₃](NO₃)₂(H₂O)₅}_n ( 2 ), [Ag₂(btmb)(N₃)₂]_n ( 3 ), and [Ag(btmb)(N₃)]_n ( 4 ). Their coordination number varies from 2 (in 1 ) to 3 (in 2 ), 4 (in 3 ), and 5 (in 4 ). Different from the single chain structure of 1 , complex 2 displays a 1D ladder‐like double chain framework, whereas complex 3 exhibits a 2D layered architecture. Complex 4 has the same anion as complex 3 but shows a different metal‐to‐ligand ratio and a 1D double‐zigzag chain structure. Both 3 and 4 have Ag ··· Ag argentophilic interactions. The ligand btmb adopts both cis or trans configuration in the studied complexes. A trans‐ or cis‐btmb ligand link silver ions with Ag ··· Ag distances of ≈?18 and 13 Å, respectively. BF₄^– and NO₃^– are non‐coordinating anions in 1 and 2 . N₃^– is the bridging anion in 3 (1,3‐bridging fashion) and 4 (1,1‐bridging fashion). These findings suggest that the coordination numbers around the Ag^I ion correlate to the coordination abilities of anions and the btmb to silver ratio. In addition, the influence of anions on thermal stability were also investigated. This work is a good example that nicely supports the less explored field of anion‐dependent structures of complexes with non‐pyridyl ligands.     

Formation and Molecular Structure of an Ion Pair Iron (II) Compound Derived from 2,6‐Bis‐ [1‐(2,6‐dibromophenylimino) ‐ethyl] pyridine and 2‐Acetyl‐6‐[1‐(2, 6‐dibromophenylimino)‐ethyl] pyridine

Two novel tridentate ligands of 2,6‐bis‐[l‐(2,6‐dibromophenylimino) ethyl] pyridine (L₁) and2‐acetyl‐6‐[1‐(2,6‐dibromophenylimino) ethyl] pyridine (L2) have been synthesized. The iron(II) complex of L₁ and L₂ has been characterized with the crystal structure of [Fe(L₁)(L₂)]²⁺ [FeCl₄]² CH₂Cl₂ [monoclinic, P2₁ (#11), a = 1.0562(4), b = 2.0928(4), c = 1.2914(2) nm, β = 100.12°, V = 2.810(1) nm³ D_c = 1.879 g/cm³ and Z = 2].     

A novel C2 symmetric chiral stationary phase with N‐[(4‐Methylphenyl)sulfonyl]‐l‐leucine as chiral side chains

In this study, a series of chiral stationary phases based on N‐[(4‐methylphenyl)sulfonyl]‐l ‐leucine amide, whose enantiorecognition property has never been studied, were synthesized. Their enantioseparation abilities were chromatographically evaluated by 67 enantiomers. The chiral stationary phase derived from N‐[(4‐methylphenyl)sulfonyl]‐l ‐leucine showed much better enantioselectivities than that based on N‐(4‐methylbenzoyl)‐l ‐leucine amide. The construction of C₂ symmetric chiral structure greatly improved the enantiorecognition performance of the stationary phase. The C₂ symmetric chiral stationary phase exhibited superior enantioresolutions to other chiral stationary phases for most of the chiral analytes, especially for the chiral analytes with C₂ symmetric structures. By comparing the enantioseparations of the enantiomers with similar structures, the importance of hydrogen bond interaction, π–π interaction, and steric hindrance on enantiorecognition was elucidated. The enantiorecognition mechanism of trans‐N,N′‐(1,2‐diphenyl‐1,2‐ethanediyl)bis‐acetamide, which had an excellent separation factor on the C₂ symmetric chiral stationary phase, was investigated by ¹H‐NMR spectroscopy and 2D ¹H‐¹H nuclear overhauser enhancement spectroscopy.