Two dimeric CuII benzoate derivatives solvated with aceto­nitrile

The title compounds, tetrakis(μ‐benzoato‐O:O′)­bis(2,6‐di­amino­pyridine)‐1κN,2κN‐dicopper(II)–aceto­nitrile (1/2), [Cu₂(C₇H₅O₂)₄(C₅H₇N₃)₂]·2C₂H₃N, (I), and bis­(aceto­nitrile)‐1κN,2κN‐tetrakis(μ‐benzoato‐O:O′)­dicopper(II)–aceto­nitrile (1/1.5), [Cu₂(C₇H₅O₂)₄(C₂H₃N)₂]·1.5C₂H₃N, (II), crystallize as aceto­nitrile solvates exhibiting different stability. They have similar molecular structures with discrete dimeric units located at crystallographic inversion centres. The copper ions are bridged by four benzoate groups and neutral N‐donor ligands, viz. 2,6‐di­amino­pyridine in (I) and aceto­nitrile in (II), are coordinated at apical positions. The diverse stability is probably due to hydrogen‐bond interactions of the solvated aceto­nitrile mol­ecules with neighbouring dimers in compound (I).     

Kinetic and electrochemical study of nitrile adducts of tetrachloro-bis (1,2-bis(diphenylphosphine)methane)dirhenium(II)

Summary The addition of two nitrile ligands to the complex Re₂Cl₄-(dppm)₂ (dppm= 1,2-bis(diphenylphosphine)methane)in CH₂Cl₂ solution has been investigated electrochemically. Upon addition of one equivalent of nitrile NCR (R = aromatic or aliphatic group) to the CH₂Cl₂/0.1m tetra-N-butylammonium hexafluorophosphate (TBAH) solution, Re₂Cl₄(dppm)₂(NCR) is formed immediately, without dissociation of chloride; electrochemical investigation indicates this nitrile addition is reversible upon oxidation of the dirhenium complex. On addition of two or more equivalents of nitrile, a slow ligand substitution takes place with addition of a second nitrile and concomitant loss of a chloride ion to form [Re₂Cl₃-(dppm)₂(NCR)₂]⁺. The rate of addition of nitrile to Re₂Cl₄(dppm)₂(NCR) appears to depend on the electrondonating or electron-withdrawing abilities of the ligand. The change from monoadduct to diadduct was followed with differential pulse voltammetry for various concentrations of added nitrile. The addition was found to be first order in nitrile.     

Reactions of rac‐(ebthi)M(η2‐Me3SiC2SiMe3) (M=Ti,Zr) with Aryl Nitriles

The reactions of the Group 4 metallocene alkyne complexes rac‐(ebthi)M(η²‐Me₃SiC₂SiMe₃) ( 1 a : M=Ti, 1 b : M=Zr; rac‐(ebthi)=rac‐1,2‐ethylene‐1,1′‐bis(η⁵‐tetrahydroindenyl)) with Ph?C?N were investigated. For 1 a , an unusual nitrile–nitrile coupling to 1‐titana‐2,5‐diazacyclopenta‐2,4‐diene ( 2 ) at ambient temperature was observed. At higher temperature, the C?C coupling of two nitriles resulted in the formation of a dinuclear complex with a four‐membered diimine bridge ( 3 ). The reaction of 1 b with Ph?C?N afforded dinuclear compound 4 and 2,4,6‐triphenyltriazine. Additionally, the reactivity of 1 b towards other nitriles was investigated.     

The effect of organic nitriles on the radiation induced polymerization of styrene

The effect of a range of 10 organic nitriles on the radiation-induced polymerization of styrene was studied. A dose rate of 4.4 rad s^?1 was used. A rate of polymerization of styrene (1.744 mol L^?1 of toluene solution) of 5.0 × 10^?7 mol L^?1 s^?1 was found. With organic nitriles present (styrene:nitrile ratio of 1:0.28) the rate of polymerization increased. Rates in the range of 5.5 × 10^?7 ?5.2 × 10^?6 mol L^?1 s^?1, depending on the nitrile present, were obtained. The polymers were partially characterized and evidence of involvement of each of the nitriles in the polymer chains was revealed. The increase in rate of polymerization has been attributed to the part played by nitrile radicals in the initiation of styrene polymerization. Radical yield values [as G(nitrile radical)] were derived from the relevant rate expressions. Values ranged from 2.7 to 49.5, depending on the particular nitrile. Corresponding values of G(nitrile radical) in the range of 5.1–129.4 were obtained by the manipulation of number-average molar mass data. Values of k_pk_t of approximately 2 × 10^?5 L mol^?1 s^?1 were found. Trommsdorff types of effect are absent from these systems.     

Deoxy-nitrosugars. 11th Communication. Reactions of 1-C-nitroglycosyl halides and 1-C-nitroglycosyl sulfones with dialkyl-phosphite anions: Nucleophilic attack vs. single-electron transfer

Treatment of the chloro-nitro-ribofuranose 7 with KPO(OMe)₂ gave the O-amino phosphate 8 (5 %) and the nitrile 9 (62 %). Compound 9 was also obtained by the reaction of 8 with KPO(OMe)₂, and its structure was established by X-ray analysis. Treatment of the chloro-nitro-mannofuranose 10 , the bromo-nitro-ribofuranose 14 , or the bromo-nitro-mannofuranose 16 , respectively, with the K or Na salt of HPO(OMe)₂ lead also to O-amino phosphates and nitriles. The (1-C-nitroglycosyl)phosphonate 22 was obtained (21 %) together with the nitrile 21 (51 %) from the chloro-nitro-mannofuranose 10 and KPO(OEt)₂. The reaction of the 1-C-nitroglycosyl sulfone 25 (NO₂-group endo) with KPO(OEt)₂ gave the (1-C-nitroglycosyl)phosphonate 22 (61%) and the nitrile 21 (11 %), whilst the anomeric sulfone 26 (NO₂-group exo) gave 22 (15 %) and 21 (58 %). In the presence of [18] crown-6, a mixture of the anomers 25 and 26 gave the (1-C-nitroglycosyl)phosphonate 22 in 67 % yield together with 21 (13 %). These findings are rationalized as the result of a competition between a nucleophilic attack of the dialkyl-phosphite anions on the NO₂-group leading ultimately to the nitrile 21 and a single-electron transfer reaction leading to the (1-C-nitroglycosyl)phosphonate 22 .     

Cationic polyelectrolytes. III. Nitrile-group reaction of macromolecular compounds with N,N-dialkylaminoalkylamines

The chemical reaction in aqueous medium of polyacrylonitrile and acrylonitrile–vinyl acetate co-polymer using asymmetrical diamines of H₂N? (CH₂)_m? NR₂ (m = 2,3) structure was studied. It was found that the nitrile group is modified to an dialkylaminoalkylacrylamide group; also determined were the reaction conditions required to obtain the highest degree of chemical transformation of the nitrile groups. All modified compounds were characterized by analytical spectroscopy (IR and ¹H NMR) and by rheological methods. It was also established that glutaronitrile can be used as a low-molecular-weight model to study the chemical transformation of nitrile groups in polyacrylonitrile and related polymers.     

Dárivás C-glycosyliques. IX. Syntháse de spiro-Δ2-isoxazolines et de spiro-Δ1-pyrazolines à partir du dásoxy-3-di-O-isopropylidène 1, 2: 5, 6-máthylène-3-α-D-ribo-hexofurannose. Communication práliminaire

Treatment of 3-deoxy-1, 2:5, 6-di-O-isopropylidène-3C-méthylene-α-D -ribo-hexofuranose with aromatic nitrile oxides led to spiro-Δ₂-isoxazolines, whereas a Δ₁-pyrazoline was obtained by reacting the same C-methylenic sugar with diazomethane. Properties of these compounds, a new class of carbohydrates, and 5, 6-di-O-acetyl derivatives thereof are described.     

Catalytic Hydrogen Production by Ruthenium Complexes from the Conversion of Primary Amines to Nitriles: Potential Application as a Liquid Organic Hydrogen Carrier

The potential application of the primary amine/nitrile pair as a liquid organic hydrogen carrier (LOHC) has been evaluated. Ruthenium complexes of formula [(p‐cym)Ru(NHC)Cl₂] (NHC=N‐heterocyclic carbene) catalyze the acceptorless dehydrogenation of primary amines to nitriles with the formation of molecular hydrogen. Notably, the reaction proceeds without any external additive, under air, and under mild reaction conditions. The catalytic properties of a ruthenium complex supported on the surface of graphene have been explored for reutilization purposes. The ruthenium‐supported catalyst is active for at least 10 runs without any apparent loss of activity. The results obtained in terms of catalytic activity, stability, and recyclability are encouraging for the potential application of the amine/nitrile pair as a LOHC. The main challenge in the dehydrogenation of benzylamines is the selectivity control, such as avoiding the formation of imine byproducts due to transamination reactions. Herein, selectivity has been achieved by using long‐chain primary amines such as dodecylamine. Mechanistic studies have been performed to rationalize the key factors involved in the activity and selectivity of the catalysts in the dehydrogenation of amines. The experimental results suggest that the catalyst resting state contains a coordinated amine.     

(Z)‐3‐(1H‐Indol‐3‐yl)‐2‐(3‐thienyl)­acrylo­nitrile and (Z)‐3‐[1‐(4‐tert‐butyl­benzyl)‐1H‐indol‐3‐yl]‐2‐(3‐thienyl)­acrylo­nitrile

(Z)‐3‐(1H‐Indol‐3‐yl)‐2‐(3‐thienyl)­acrylo­nitrile, C₁₅H₁₀N₂S, (I), and (Z)‐3‐[1‐(4‐tert‐butyl­benzyl)‐1H‐indol‐3‐yl]‐2‐(3‐thienyl)­acrylo­nitrile, C₂₆H₂₄N₂S, (II), were prepared by base‐catalyzed reactions of the corresponding indole‐3‐carbox­aldehyde with thio­phene‐3‐aceto­nitrile. ¹H/¹³C NMR spectral data and X‐ray crystal structures of compounds (I) and (II) are presented. The olefinic bond connecting the indole and thio­phene moieties has Z geometry in both cases, and the mol­ecules crystallize in space groups P2₁/c and C2/c for (I) and (II), respectively. Slight thienyl ring‐flip disorder (ca 5.6%) was observed and modeled for (I).     

Targeting the Substrate Binding Site of E. coli Nitrile Reductase QueF by Modeling,Substrate and Enzyme Engineering

Nitrile reductase QueF catalyzes the reduction of 2‐amino‐5‐cyanopyrrolo[2,3‐d]pyrimidin‐4‐one (preQ₀) to 2‐amino‐5‐aminomethylpyrrolo[2,3‐d]pyrimidin‐4‐one (preQ₁) in the biosynthetic pathway of the hypermodified nucleoside queuosine. It is the only enzyme known to catalyze a reduction of a nitrile to its corresponding primary amine and could therefore expand the toolbox of biocatalytic reactions of nitriles. To evaluate this new oxidoreductase for application in biocatalytic reactions, investigation of its substrate scope is prerequisite. We report here an investigation of the active site binding properties and the substrate scope of nitrile reductase QueF from Escherichia coli. Screenings with simple nitrile structures revealed high substrate specificity. Consequently, binding interactions of the substrate to the active site were identified based on a new homology model of E. coli QueF and modeled complex structures of the natural and non‐natural substrates. Various structural analogues of the natural substrate preQ₀ were synthesized and screened with wild‐type QueF from E. coli and several active site mutants. Two amino acid residues Cys190 and Asp197 were shown to play an essential role in the catalytic mechanism. Three non‐natural substrates were identified and compared to the natural substrate regarding their specific activities by using wild‐type and mutant nitrile reductase.     

New methods of preparation of nitrile oxides and the corresponding disubstituted furoxans by interaction of N2O4 with salts of substituted dinitromethanes

A new method of generation of nitrile oxides through interaction of N₂O₄ with salts of substituted dinitromethanes (1) has been worked out. It has been shown by¹H,¹³C,¹⁴N NMR spectroscopy that this reaction proceeds via dinitronitrosomethyl intermediates (one of these has been isolated), and that the reaction is feasible only for substituents capable of conjugation with the nitrile oxide fragment. On the basis of cyclodimerization of the obtained nitrile oxides, preparative methods of synthesis of symmetrically substituted furoxans have been developed.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 147–151, January, 1993.     

Two different anionic manganese(II) coordination polymers constructed through dicyanamide coordination bridges

In order to explore new metal coordination polymers and to search for new types of ferroelectrics among hybrid coordination polymers, two manganese dicyanamide complexes, poly[tetramethylammonium [di‐μ₃‐dicyanamido‐κ⁶N¹:N³:N⁵‐tri‐μ₂‐dicyanamido‐κ⁶N¹:N⁵‐dimanganese(II)]], {[(CH₃)₄N][Mn₂(NCNCN)₅]}_n, (I), and catena‐poly[bis(butyltriphenylphosphonium) [[(dicyanamido‐κN¹)manganese(II)]‐di‐μ₂‐dicyanamido‐κ⁴N¹:N⁵]], {[(C₄H₉)(C₆H₅)₃P]₂[Mn(NCNCN)₄]}_n, (II), were synthesized in aqueous solution. In (I), one Mn^II cation is octahedrally coordinated by six nitrile N atoms from six anionic dicyanamide (dca) ligands, while the second Mn^II cation is coordinated by four nitrile N atoms and two amide N atoms from six anionic dca ligands. Neighbouring Mn^II cations are linked together by μ‐1,5‐ and μ‐1,3,5‐bridging dca anions to form a three‐dimensional polymeric structure. The anionic framework exhibits a solvent‐accessible void of 289.8 ų, amounting to 28.0% of the total unit‐cell volume. Each of the cavities in the network is occupied by only one tetramethylammonium cation. In (II), each Mn^II cation is octahedrally coordinated by six nitrile N atoms from six dca ligands. Neighbouring Mn^II cations are linked together by double dca bridges to form a one‐dimensional polymeric chain, and C—H...N hydrogen‐bonding interactions are involved in the formation of the one‐dimensional layer structure.     

2,3‐Bis(4‐nitro­benzyl­thio)­maleo­nitrile

The maleo­nitrile moiety of the title compound, (2Z)‐2,3‐bis­[(4‐nitro­benzyl)­sulfanyl]­but‐2‐ene­di­nitrile, C₁₈H₁₂N₄O₄S₂, is almost planar. The two benzene rings are nearly parallel to each other and perpendicular to the maleo­nitrile plane. Intermolecular S?S and π–π interactions are observed in the crystal structure.     

Spatiotemporal Studies of the One-Dimensional Coordination Polymer [Fe(ebtz)2(C2H5CN)2](BF4)2: Tug of War between the Nitrile Reorientation Versus Crystal Lattice as a Tool for Tuning the Spin Crossover Properties**

Reaction of 1,2-di(tetrazol-2-yl)ethane (ebtz) with Fe(BF₄)₂⋅6 H₂O in different nitriles yields one-dimensional coordination polymers [Fe(ebtz)₂(RCN)₂](BF₄)₂⋅nRCN (n=2 for R=CH₃ ( 1 ) and n=0 for R=C₂H₅ ( 2 ) C₃H₇ ( 3 ), C₃H₅ ( 4 ), CH₂Cl ( 5 )) exhibiting spin crossover (SCO). SCO in 1 and 3 – 5 is complete and occurs above 160 K. In 2 , it is shifted to lower temperatures and is accompanied by wide hysteresis (T_1/2^↓=78 K, T_1/2^↑=123 K) and proceeds extremely slowly. Isothermal (80 K) time-resolved single-crystal X-ray diffraction studies revealed a complex nature for the HS→LS transition in 2 . An initial, slow stage is associated with shrinkage of polymeric chains and with reduction of volume at 77 % (in relation to the difference between cell volumes V_HS−V_LS) whereas only 16 % of iron(II) ions change spin state. In the second stage, an abrupt SCO occurs, associated with breathing of the crystal lattice along the direction of the Fe–nitrile bonds, while the nitriles reorient. HS→LS switching triggered by light (808 nm) reveals the coupling of spin state and nitrile orientation. The importance of this coupling was confirmed by studies of [Fe(ebtz)₂(C₂H₅CN/C₃H₇CN)₂](BF₄)₂ mixed crystals ( 2 a , 2 b ), showing a shift of T_1/2 to higher values and narrowing of the hysteresis loop concomitant with an increase of the fraction of butyronitrile. This increase reduces the capability of nitrile molecules to reorient. Density functional theory (DFT) studies of models of 1 – 5 suggest a particular possibility of 2 to adopt a low (140–145°) value of its Fe-N-C(propionitrile) angle.     

Unusual Nitrile–Nitrile and Nitrile–Alkyne Coupling of FcCN and FcCCCN

The reactions of the Group 4 metallocene alkyne complexes, [Cp*₂M(η²‐Me₃SiC₂SiMe₃)] ( 1 a : M=Ti, 1 b : M=Zr, Cp*=η⁵‐pentamethylcyclopentadienyl), with the ferrocenyl nitriles, Fc?C?N and Fc?C?C?C?N (Fc=Fe(η⁵‐C₅H₅)(η⁵‐C₅H₄)), is described. In case of Fc?C?N an unusual nitrile–nitrile C?C homocoupling was observed and 1‐metalla‐2,5‐diaza‐cyclopenta‐2,4‐dienes ( 3 a , b ) were obtained. As the first step of the reaction with 1 b , the nitrile was coordinated to give [Cp*₂Zr(η²‐Me₃SiC₂SiMe₃)(N?C‐Fc)] ( 2 b ). The reactions with the 3‐ferrocenyl‐2‐propyne‐nitrile Fc?C?C?C?N lead to an alkyne–nitrile C?C coupling of two substrates and the formation of 1‐metalla‐2‐aza‐cyclopenta‐2,4‐dienes ( 4 a , b ). For M=Zr, the compound is stabilized by dimerization as evidenced by single‐crystal X‐ray structure analysis. The electrochemical behavior of 3 a , b and 4 a , b was investigated, showing decomposition after oxidation, leading to different redox‐active products.     

catena-Poly[[(acetonitrile-N)dichlorocopper(II)]-μ-2,5-dimethylpyrazine-κ2N:N′]

In the structure of the title compound, [CuCl₂­(C₂H₃N)(C₆H₈N₂)], each Cu²⁺ cation is surrounded by two 2,5-di­methyl­pyrazine ligands, one aceto­nitrile ligand and two Cl⁻ anions within a distorted tetragonal pyramid. The aceto­nitrile ligand, which forms the apex of the pyramid, the Cu²⁺ cation and the Cl⁻ anions are all located in general positions, whereas each of the 2,5-di­methyl­pyrazine ligands is located about a centre of inversion. The 2,5-di­methyl­pyrazine ligands connect the Cu²⁺ cations viaμ-N:N′ coordination to form chains.     

(Aceto­nitrile)­[2,6‐bis­(pyrazol‐1‐yl)­pyridine](isonicotin­amide)copper(II)–tetra­fluoro­borate–aceto­nitrile (1/2/2)

Molecules of the title compound, [Cu(C₂H₃N)(C₁₁H₉N₅)(C₆H₆N₂O)](BF₄)₂·2C₂H₃N, comprise (aceto­nitrile)[2,6‐bis(pyrazol‐1‐yl)­pyridine](isonicotin­amide)copper(II) cations, tetra­fluoro­borate anions and lattice aceto­nitrile mol­ecules. The cations have distorted square‐pyramidal geometries in which the N₃‐donor, viz. 2,6‐bis­(pyrazol‐1‐yl)­pyridine, and the N‐donor, viz. the isonicotin­amide ligand, occupy the four basal positions, with the coordinated aceto­nitrile N‐donor atom occupying the apical position. Pairs of cations are linked by N—H?F hydrogen bonds through tetra­fluoro­borate anions, forming centrosymmetric dimers, which are further linked by C—H?O hydrogen bonds into two‐dimensional undulating sheets, three of which interpenetrate to generate a two‐dimensional network.     

Aqueous-Phase Nitrile Hydration Catalyzed by an In Situ Generated Air-Stable Ruthenium Catalyst

RuCl₂(PTA)₄ (PTA=1,3,5-triaza-7-phosphaadamantane) is an active, recyclable, air-stable, aqueous-phase nitrile hydration catalyst. The development of an in situ generated aqueous-phase nitrile hydration catalyst (RuCl₃⋅3 H₂O+6 equivalents PTA) is reported. The activity of the in situ catalyst is comparable to RuCl₂(PTA)₄. The effects of [PTA] on the activity of the reaction were investigated: the catalytic activity, in general, increases as the pH goes up, which shows a positive correlation with [PTA]. The pH effects were further explored for both the in situ and RuCl₂(PTA)₄ catalyzed reaction in phosphate buffer solutions with particular attention given to pH 6.8 buffer. Increased catalytic activity was observed at pH 6.8 versus water for both systems with turnover frequency (TOF) up to 135 h⁻¹ observed for RuCl₂(PTA)₄ and 64 h⁻¹ for the in situ catalyst. Catalyst loading down to 0.001 mol % was examined with turnover numbers as high as 22 000 reported. Similar to the preformed catalyst, RuCl₂(PTA)₄, the in situ catalyst could be recycled more than five times without significant loss of activity from either water or pH 6.8 buffer.     

First Synthesis of Dopamine and Rotigotin Analogue 2-Amino-6,8-dimethoxy-1,2,3,4-tetrahydronaphthalene

The title compound was synthesized starting from 3-(3,5-dimethoxyphenyl)acrylic acid in 11 steps with 30% total yield. The reaction sequence hydrogenation of acrylic acid, reduction of acid to alcohol derivative with LiAlH₄, reaction of alcohol with CBr₄/PPh₃, substitution reaction of alkyl halide to nitrile derivative with NaCN, hydrolysis of nitrile with NaOH, cyclization reaction of acid with PPA to give 1-tetralone, α-carboxylation of tetralone with Me₂CO₃ in the presence of NaH, reduction of ketone group with Et₃SiH, hydrolysis of ester, Curtius rearrangement of acid with diphenylphosphoryl azide followed by conversion to carbamate, and finally hydrogenolysis of carbamate afforded 2-amino-6,8-dimethoxy-1,2,3,4-tetrahydronaphthalene hydrogen chloride salt.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]     

The properties of supported rhenium catalysts in the dehydrogenation of cyclohexane

The 2 % Re/sibunite catalyst is more active than 2 % Re/-Al₂O₃ and 2 % Re/-Al₂O₃ catalysts in the dehydrogenation of cyclohexane into benzene (T = 350 °C,w = 0.5 h–1). The substitution of NH₄ReO₄ by HReO₄ in the preparation of the catalyst enhances its activity by a factor of 1.3. Treatment with HNO₃ or oxalic acid increases the selectivity by a factor of 1.2 and 1.35, respectively, the overall conversion of cyclohexane being 32–40 %.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 2119–2121, August, 1996.