Hydrogen Bonding in Imidazolium Nitrates [1]

The imidazolium nitrates [ImH](NO₃) ( 1 ) and [ImBr](NO₃) ( 2 ) are obtained from the corresponding bromides [ImH]Br ( 3 ) and [ImBr]Br ( 4 ) and AgNO₃ in excellent yields (Im = 2, 3‐dihydro‐1, 3‐diisopropyl‐4, 5‐dimethylimidazol‐2‐ylidene). The crystal structures of 1 and 2 consist of infinite linear chains of ions linked by H···O and Br···O contacts. In addition, stacks consisting of imidazolium and nitrate ions in the sequence ImBr/NO₃/ImBr/NO₃··· with parallel orientation of their plains are detected in 2 . The crystal structure of 3 is also reported.     

Two phosphate–imidazole complexes with and without a hydrogen‐bonded guest mol­ecule

The mol­ecular structures of the complexes imidazolium 6,6′‐di‐tert‐butyl‐4,4′‐dimethyl‐2,2′‐thio­diphenyl phosphate, C₃H₅N₂⁺·C₂₂H₂₈O₄PS⁻, (I), and imidazolium 6,6′‐di‐tert‐butyl‐4,4′‐dimethyl‐2,2′‐thio­diphenyl phosphate diisopropyl hydrazo­dicarboxyl­ate hemisolvate, C₃H₅N₂⁺·C₂₂H₂₈O₄PS⁻·0.5C₈H₁₆N₂O₄, (II), have been determined. While (I) forms the expected hydrogen‐bonded chain utilizing the two imidazole N‐bound H atoms, in (II), the substituted hydrazine solvent mol­ecule inserts itself between the chains. Compound (I) exhibits a strong N—H⋯O hydrogen bond, with an N⋯O distance of 2.603 (2) Å. The hydrazine solvent molecule in (II) lies about a twofold axis and the N‐bound H atoms are involved in bifurcated hydrogen bonds with phosphate O atoms. A C‐bound H atom of the imidazolium cation is involved in a C—H⋯O inter­action with a carbonyl O atom of the hydrazine solvent mol­ecule.     

Synthesis and Structure of Ionic Liquids Containing the ­[Al(OC6H4CN)4]– Anion

The synthesis, structure, and physical properties of ionic liquids (IL) bearing the novel [Al(O–C₆H₄–CN)₄]^– ion as counterion to the commonly used [NR₄]⁺, [PR₄]⁺ and imidazolium ions are reported. Both the influence of the alkyl chain length as well as the functionalization with cyano groups is studied. These ILs are easily obtained by reaction of Ag[Al(O–C₆H₄–CN)₄] with the corresponding ammonium, phosphonium, and imidazolium halides. The stability towards electrophilic cations was investigated. All prepared salts have a window for the liquid phase of ca. 200 °C and are thermally stable up to 450 °C. The solid‐state structures reveal only weak cation ··· anion and anion ··· anion interactions in accord with the observed low melting points (glass transition points).     

A Sterically Hindered Phosphonic Acid with a Hydrogen‐Bonded Cage Structure: [4‐tert‐Bu‐2,6‐Mes2‐C6H2P(O)(OH)2·H2O]4

The synthesis and molecular structure of the novel phosphonic acid 4‐tert‐Bu‐2,6‐Mes₂‐C₆H₂P(O)(OH)₂ ( 1 ) is reported. Compound 1 crystallizes in form of its monohydrate as a hydrogen‐bonded cluster ( 1·H₂O )₄ comprizing four phosphonic acid molecules (O···O 2.383(3)‐3.006(4) Å). Additionally, sterically hindered terphenyl‐substituted phosphorus compounds of the type 4‐tert‐Bu‐2,6‐Mes₂‐C₆H₂PR(O)(OH) ( 5 , R = H; 7 , R = O₂CC₆H₄‐3‐Cl; 9 , R = OEt) were prepared, which all show dimeric hydrogen‐bonded structures with O···O distances in the range 2.489(2)–2.519(3) Å. Attempts at oxidizing 5 using H₂O₂, KMnO₄, O₃, or Me₃NO in order to give 1 failed. Crystallization of 5 in the presence of Me₃NO gave the novel hydrogen bonded aggregate 4‐tert‐Bu‐2,6‐Mes₂‐C₆H₂PH(O)(OH)·ONMe₃ ( 6 ) showing an O–H···O distance of 2.560(4) Å.     

Polyacetylene and Polynorbornene Derivatives Carrying TEMPO. Synthesis and Properties as Organic Radical Battery Materials

Summary: 2,2,6,6‐Tetramethylpiperidine 1‐oxyl (TEMPO)‐containing N‐propargylamide HCCCH₂NHCO‐4‐TEMPO ( 1 ), propargyl ester HCCCH₂OCO‐4‐TEMPO ( 2 ), phenylacetylene derivative HCCC₆H₃‐3,4‐(CO₂‐4‐TEMPO)₂ ( 3 ), and norbornene diester monomers, NB‐2,3‐exo,exo‐(CH₂OCO‐4‐TEMPO)₂ ( 4 ), NB‐2,3‐endo,exo‐(COO‐4‐TEMPO)₂ ( 5a ), NB‐2,3‐endo,endo‐(COO‐4‐TEMPO)₂ ( 5b ) (NB = norbornene, TEMPO = 2,2,6,6‐tetramethyl‐1‐piperidinyloxyl) were synthesized and polymerized with rhodium and ruthenium catalysts. Monomers 2 , 5a , and 5b gave polymers with number‐average molecular weights of 47 000–185 000 in 59–100% yields, while 1 , 3 , and 4 gave polymers insoluble in common organic solvents in 88–100% yields. The capacities of cells fabricated with poly( 1 ), poly( 2 ), and poly( 3 ) were 67, 82, and 23 Ah · kg⁻¹ based on the weight, respectively. The capacity of poly( 5a )‐based cell reached the theoretical value (109 Ah · kg⁻¹) of the polymer.

Charge–discharge curves of poly( 5a ) at a current density of 0.13 mA · cm⁻² (100 mA · g⁻¹_{‐cathode active material}) in the voltage range of 2.5–4.2 V.     

Imidazole‐coordinated monodentate NHC–Pd(II) complex derived from proline and its application to the coupling reaction of arylboronic acids with carboxylic acid anhydrides in water at room temperature

Cleavage of a C N bond of imidazolium salt derived from N‐phenyl‐substituted proline was observed in this laboratory. A novel imidazole‐coordinated monodentate NHC–Pd(II) complex 5 was obtained as the sole product in good yield in the reaction of imidazolium salt 4 with Pd(OAc)₂ in refluxing THF. The structure of complex 5 was determined unambiguously by an X‐ray diffraction. The complex was found to be a good catalyst in the cross‐coupling reaction of arylboronic acids with carboxylic acid anhydrides in water at room temperature. Copyright © 2011 John Wiley & Sons, Ltd.     

Preparation and Electrochemistry Properties of a New Polyoxometalate‐Based Supramolecular Assembly

A polyoxometalate‐based supramolecular assembly with the formula (Hcpy)₆H₂[PMo₁₂O₄₀] ( 1 ) [cpy = 4‐(5‐chloropyridin‐2‐yl)pyridine] was prepared and characterized. Noncovalent intermolecular interactions including hydrogen bonds (N–H ··· O–Mo, N–H ··· H–N, and C–H ··· O–Mo), halogen (C–Cl ··· O–Mo), and face‐to‐face π packing coexist in crystal 1 , which serves the insolubility of 1 in aqueous solution. Compound 1 was used as a solid material to fabricate a bulk‐modified carbon paste electrode by direct mixing. Electrochemistry results indicated that 1 is possessed of electrocatalytic activities toward the reduction reactions of chlorate, hydrogen peroxide, and nitrite.     

Catalytic polymerization of phenylacetylene with dimeric [Rh(OMe)(cod)]2 complex in ionic liquids

Dimeric rhodium(I) complex [Rh(OMe)(cod)]₂ was found to be an active catalyst of phenylacetylene polymerization to poly(phenylacetylene) (PPA) in ionic liquids containing imidazolium or pyridinium cations. The highest yield of PPA (92%) was obtained in 1‐butyl‐4‐methylpyridinium tetrafluoroborate as reaction medium. The yield of PPA in imidazolium ionic liquids containing BF₄^? or PF₆^? anions increased to 83–99% when Et₃N or cycloocta‐1,5‐diene were added as co‐catalysts. In 1‐methyl‐3‐octylimidazolium chloride (MOI · Cl) polymerization rate was much lower than in other ionic liquids, although the highest M_w (72 400) was obtained. Spectroscopic studies confirmed that [Rh(OMe)(cod)]₂ reacted with MOI · Cl forming new carbene Rh(I) complex, which can participate in the polymerization process. Copyright © 2006 John Wiley & Sons, Ltd.     

Substituted 2,2′‐Bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyl Complexes of Zinc

The condensation reaction of 2,2′‐diamino‐4,4′‐dimethyl‐6,6'‐dibromo‐1,1′‐biphenyl with 2‐hydroxybenzaldehyde as well as 5‐methoxy‐, 4‐methoxy‐, and 3‐methoxy‐2‐hydroxybenzaldehyde yields 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyl ( 1a ) as well as the 5‐, 4‐, and 3‐methoxy‐substituted derivatives 1b , 1c , and 1d , respectively. Deprotonation of substituted 2,2′‐bis(salicylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls with diethylzinc yields the corresponding substituted zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐1,1′‐biphenyls ( 2 ) or zinc 2,2′‐bis(2‐oxidobenzylideneamino)‐4,4′‐dimethyl‐6,6′‐dibromo‐1,1′‐biphenyls ( 3 ). Recrystallization from a mixture of CH₂Cl₂ and methanol can lead to the formation of methanol adducts. The methanol ligands can either bind as Lewis base to the central zinc atom or as Lewis acid via a weak O–H ··· O hydrogen bridge to a phenoxide moiety. Methanol‐free complexes precipitate as dimers with central Zn₂O₂ rings.     

Hydrogen‐bonded structures of the isomeric compounds of quinoline with 2‐chloro‐5‐nitrobenzoic acid, 3‐chloro‐2‐nitrobenzoic acid, 4‐chloro‐2‐nitrobenzoic acid and 5‐chloro‐2‐nitrobenzoic acid

The structures of four isomeric compounds, all C₇H₄ClNO₄·C₉H₇N, of quinoline with chloro‐ and nitro‐substituted benzoic acid, namely, 2‐chloro‐5‐nitrobenzoic acid–quinoline (1/1), (I), 3‐chloro‐2‐nitrobenzoic acid–quinoline (1/1), (II), 4‐chloro‐2‐nitrobenzoic acid–quinoline (1/1), (III), and 5‐chloro‐2‐nitrobenzoic acid–quinoline (1/1), (IV), have been determined at 185 K. In each compound, a short hydrogen bond is observed between the pyridine N atom and a carboxyl O atom. The N...O distances are 2.6476 (13), 2.5610 (13), 2.5569 (12) and 2.5429 (12) Å for (I), (II), (III) and (IV), respectively. Although in (I) the H atom in the hydrogen bond is located at the O site, in (II), (III) and (IV) the H atom is disordered in the hydrogen bond over two positions with (N site):(O site) occupancies of 0.39 (3):0.61 (3), 0.47 (3):0.53 (3) and 0.65 (3):0.35 (3), respectively.     

N‐(Substituted benzyl)‐3,5‐bis(benzylidene)‐4‐piperidones: Synthesis and Preliminary Anti‐leukemia Activity (I)

A series of novel N‐(substituted benzyl)‐3,5‐bis(benzylidene)‐4‐piperidones 5a – 5o were synthesized with substituted benzylamines as raw materials via a series of Michael addition, Dieckmann condensation, hydrolysis decarboxylation and aldol condensation. The structures were confirmed by ¹H NMR, IR, MS techniques and elemental analysis. Assay‐based antiproliferative activity study using leukemic cell lines K562 revealed that most of the title compounds have high effectiveness in inhibiting leukemia K562 cells proliferation, among which the compounds 5g (IC₅₀=7.81 µg·mL⁻¹), 5k (IC₅₀=6.35 µg·mL⁻¹), 5l (IC₅₀=7.20 µg·mL⁻¹), and 5o (IC₅₀=5.79 µg·mL⁻¹) have better inhibition activities than standard 5‐fluorouracil (IC₅₀=8.56 µg·mL⁻¹).     

Four Complexes with the Rigid Ligand 1,4‐Bis(1H‐imidazol‐4‐yl)benzene and Varied Carboxylate Ligands

Four metal‐organic coordination polymers [Co₂(L)₃(nipa)₂]·6H₂O ( 1 ), [Cd(L)(nipa)]·3H₂O ( 2 ), [Co(L) (Hoxba)₂] ( 3 ) and [Ni₂(L)₂(oxba)₂(H₂O)]·1.5L·3H₂O ( 4 ) were synthesized by reactions of the corresponding metal(II) salts with the rigid ligand 1,4‐bis(1H‐imidazol‐4‐yl)benzene (L) and different derivatives of 5‐nitroisophthalic acid (H₂nipa) and 4,4′‐oxybis(benzoic acid) (H₂oxba), respectively. The structures of the complexes were characterized by elemental analysis, FT‐IR spectroscopy and single‐crystal X‐ray diffraction. Complexes 1 and 3 have the same one‐dimensional (1D) chain while 2 is a 6‐connected twofold interpenetrating three‐dimensional (3D) network with α ‐Po 4¹²·6³ topology based on the binuclear Cd^II subunits. Compound 4 features a puckered two‐dimensional (2D) (4,4) network, and the large voids of the packing 2D nets have accommodated the uncoordinated L guest molecules. An abundant of N–H···O, O–H···O and C–H···O hydrogen bonding interactions exist in complexes 1–4 , which contributes to stabilize the crystal structure and extend the low‐dimensional entities into high‐dimensional frameworks. Lastly, the photoluminiscent properties of compounds 2 were also investigated.     

Syntheses and Crystal Structures of Copper(II) and Silver Complexes with 5‐Methyl‐1‐(4‐Methylphenyl)‐1,2,3‐Triazol‐4‐Carboxylic Acid

Two novel complexes [Cu L ₂(MeOH)] ( 1 )and [Ag₂ L (H L )₂(MeOH)] ( 2 ) ( L = 5‐methyl‐1‐(4‐methylphenyl)‐1,2,3‐triazol‐4‐carboxylic acid) were synthesized and characterized by elemental analysis, IR and X‐ray diffraction. Complex 1 is a mononuclear structure; the molecules were assembled into an infinite 2–D supramolecular by the C–H···O weak interactions. Complex 2 is a centrosymmetric dinuclear structure with bis(unidentate) carboxylato co‐ordination mode, and the molecules were assembled into 2–D layers by C–H···O and O–H···O weak interactions.     

New class of cationic ring‐opening polymerizations of 2,2‐diphenyl‐1,3‐oxathiolanes accompanying quantitative elimination of benzophenone

Cationic polymerizations of three 2‐substituted 1,3‐oxathiolanes, 2,2‐diphenyl‐1,3‐oxathiolane ( 1a ), 5‐methyl‐2,2‐diphenyl‐1,3‐oxathiolane ( 1b ), and 4‐methyl‐2,2‐diphenyl‐1,3‐oxathiolane ( 1c ), were carried out with boron trifluoride etherate (BF₃ · OEt₂) in dichloromethane at 30 °C to obtain poly(alkylene sulfide)s accompanying the elimination of benzophenone. In the cationic polymerization of 1b and 1c , the consumption of the monomers and formation of benzophenone proceeded simultaneously. The obtained poly(propylene sulfide)s from 1b and 1c contain 41% head–head units, which is in good agreement with that of the polymer from methylthiirane with BF₃ · OEt₂. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2943–2949, 2004     

Synthesis and Structural Characterization of Cationic Complexes with Hexacoordinate Silicon(IV) and Three Bidentate 1‐Oxopyridine‐2‐olato(1–) Ligands

The cationic complexes with hexacoordinate silicon(IV), tris[1‐oxopyridine‐2‐olato(1–)]silicon(IV) trifluoromethanesulfonate ( 4 ), 4 · ¹/₂ C₅H₅NO₂, tris[1‐oxopyridine‐2‐olato(1–)]silicon(IV) ethyl sulfate–ethanol ( 5 · EtOH), and tris[1‐oxopyridine‐2‐olato(1–)]silicon(IV) isopropyl sulfate ( 6 ), were synthesized. The identities of 4 , 4 · ¹/₂ C₅H₅NO₂, 5 · EtOH, and 6 were established by elemental analyses (C, H, N, S), mass‐spectrometric studies (FAB MS) as well as solid‐state (²⁹Si) and solution (¹H, ¹³C, ¹⁹F, ²⁹Si) NMR experiments. In addition, 4 · ¹/₂ C₅H₅NO₂ was structurally characterized by single‐crystal X‐ray diffraction.     

Synthesis and Crystal Structure of Two Succinato‐Bridged Macrocyclic Nickel(II) Complexes

Two dinuclear succinato‐bridged nickel(II) complexes [Ni(RR‐L)]₂(μ‐SA)(ClO₄)₂ ( 1 ) and [Ni(SS‐L)]₂(μ‐SA)(ClO₄)₂ ( 2 ) (L = 5, 5, 7, 12, 12, 14‐hexamethyl‐1, 4, 8, 11‐tetraazacyclotetradecane, SA = succinic acid) were synthesized and characterized by EA, Circular dichroism (CD), as well as IR and UV/Vis spectroscopy. Single crystal X‐ray diffraction analyses revealed that the Ni^II atoms display a distorted octahedral coordination arrangement, and the succinato ligand bridges two central Ni^II atoms in a bis bidentate fashion to form dimers in 1 and 2 . The monomers of {[Ni(RR‐L)]₂(μ‐SA)}²⁺ and {[Ni(SS‐L)]₂(μ‐SA)}²⁺ are connected by O–H ··· O and N–H ··· O hydrogen bonds into a 1D right‐handed and left‐handed helical chain along the b axis, respectively. The homochiral natures of 1 and 2 are confirmed by the results of CD spectroscopy.     

Allyl‐Functionalised Ionic Liquids: Synthesis,Characterisation, and Reactivity

The two known Me‐ and allyl‐substituted 1H‐imidazol‐3‐ium bromides 1 and 2 , respectively, were converted to the corresponding BF and BPh salts 3 – 6 (Scheme 1). Compounds 3 and 4 were liquids at ambient temperature. Reaction of 1 or 2 with [PdCl₂] afforded the corresponding 2 : 1 imidazolium/metal complexes 7 and 8 . The latter complex, melting at 58°, can be regarded as a ‘true’ ionic liquid. Attempts to polymerise 7 by radical promotion (AIBN) were unsuccessful, but resulted in the centrosymmetric 2 : 1 complex 9 . The allyl group of 1 could be arylated (giving rise to 10 ) or hydrogenated (at 100 bar H₂ pressure). The solid‐state structures of compounds 5 – 7 and 9 were solved by means of single‐crystal X‐ray analyses (Figs. 1–4).     

Polysulfonylamine. CLXXXIV. Kristallstrukturen molekularer Triphenylphosphangold(I)‐di(4‐X‐benzolsulfonyl)‐amide: Isomorphie und dichte Packung (X = Me,F, Cl,NO2) vs. struktursteuernde Halogenbrücken C–X···Au/O (X = Br,I)

Polysulfonylamines. CLXXXIV. Crystal Structures of Molecular Triphenylphosphanegold(I) Di(4‐X‐benzenesulfonyl)amides: Isomorphism and Close Packing (X = Me, F, Cl, NO₂) vs. Structure‐Determining C–X···Au/O Halogen Bonds (X = Br, I) In order to study the structure‐determining influence that halogen bonding can exert during the course of crystallization, solid‐state structures are compared for two previously reported and four new molecular gold(I) complexes of the type Ph₃P–Au–N(SO₂–C₆H₄–4‐X)₂, each featuring linear P,N coordination at gold and two phenyl rings with varying p‐substituents X = Me, F, Cl, NO₂, Br or I. The compounds were synthesized by reactions of Ph₃PAuX (X = Cl or I) with the corresponding silver di(arenesulfonyl)amides, crystallized from dichloromethane, and characterized by low‐temperature X‐ray diffraction. The Me, F, Cl and NO₂ congeners are isomorphic and crystallize without solvent inclusion in the chiral orthorhombic space group P2₁2₁2₁ (Z′ = 1). These structures are governed by isotropic close packing via three‐dimensional 2₁ symmetry, incidentally supported by an invariant set of C–H···O=S hydrogen bonds, CH/π interactions and π/π stackings of aromatic rings; in particular, the hard halogen atoms of the fluoro and the chloro homologues are not involved in X···Au, X···O or X···X interactions. The higher homologues, with soft halogen atoms, were obtained as a dichloromethane hemisolvate for X = Br and a corresponding monosolvate for X = I, each triclinic in the centrosymmetric space group (Z′ = 1). Here, the primary structural effect is implemented by infinite chains in which translation‐related molecules are connected for the bromo compound by a bifurcated Au···Br(2)···O=S interaction, for the iodo congener by an equivalent Au···I(2)···O=S interaction and a short halogen bond C–I(1)···O=S. The latter bond is stronger than a similar C–Br···O=S interaction and induces a conformational adjustment of the (CSO₂)₂N group from the normal twofold symmetry in the bromo compound to an energetically unfavourable asymmetric form in the iodo homologue. In both cases, pairs of antiparallel molecular catemers are associated into strands via sixfold phenyl embraces, the strands are stacked to form layers, the solvent molecules are intercalated between adjacent layers, and the crystal packings are reinforced by a number of C–H···O=S hydrogen bonds and interactions of aromatic rings.     

Nucleotide–amino acid interactions in the l‐His–IMP·MeOH·H2O complex

In the crystal structure of the methanol‐solvated monohydrated complex of l ‐histidine (His) with inosine 5′‐monophosphate (IMP), namely l ‐histidinium inosine‐5′‐phosphate methanol solvate monohydrate, C₆H₁₀N₃O₂⁺·C₁₀H₁₂N₄O₈P⁻·CH₃OH·H₂O, most of the interactions between IMP anions (anti/C3′‐endo/gauche–gauche conformers) are realized between the riboses and hypoxanthine bases in a trans sugar‐edge/sugar‐edge geometry, and between the phosphate groups. The base Watson–Crick edge is involved in additional methanol‐mediated IMP...MeOH...IMP contacts. Specific and nonspecific nucleotide–amino acid (IMP...His) interactions engage the Hoogsteen edges of the base and phosphate group, respectively. Additional stabilization of His...IMP contacts is provided by π–π stacking between the imidazolium ring of His and the hypoxanthine base of IMP. The results may indicate the possible recognition mechanism between His and IMP.     

Synthesis,Crystal Structure and Magnetic Behaviour of {[Co(dimb)2(H2O)2]·(NO3)2·(H2O)2}n

The title complex {[Co(dimb)₂(H₂O)₂]·(NO₃)₂·(H₂O)₂}_n ( 1 ) (dimb = 1,3‐di(imidazol‐1‐ylmethyl)‐5‐methylbenzene) has been hydrothermally synthesized by the reaction of dimb with Co(NO₃)₂·6H₂O in aqueous solution. The cobalt(II) atoms are linked by bridging dimb ligands to form 2D corrugated and wavy networks containing Co₄(dimb)₄ macrocyclic motifs. Two neighboring independent layers interlinked each other in a parallel fashion to construct three‐dimensional structure by O–H···O, N–H···O and C–H···O hydrogen bonds. Magnetic measurement shows the weak antiferromagnetic interaction with a one‐dimensional chain model in the range of 5–300 K, with J of –0.68 cm⁻¹.