Hydrogen‐bonding one‐dimensional chains containing the R42(8) motif in the ammonium salts 1‐naphthylammonium iodide and naphthalene‐1,8‐diyldiammonium diiodide

In 1‐naphthylammonium iodide, C₁₀H₁₀N⁺·I⁻, and naphthalene‐1,8‐diyldiammonium diiodide, C₁₀H₁₂N₂²⁺·2I⁻, the predominant hydrogen‐bonding pattern can be described using the graph‐set notation R₄²(8). This is the first report of a structure of a diprotonated naphthalene‐1,8‐diyldiammonium salt.     

(8‐Dimethylamino‐1‐naphthyl)dimethylammonium 3‐carboxy‐1,4,5,‐6,7,7‐hexachlorobicyclo[2.2.1]hept‐5‐ene‐2‐carboxylate hydrate

The structure of the title compound, C₁₄H₁₉N₂⁺·C₉H₃Cl₆O₄^?·H₂O, consists of singly ionized 1,4,5,6,7,7‐hexachlorobicyclo[2.2.1]hept‐5‐ene‐2,3‐dicarboxylic acid anions and protonated 1,8‐bis(dimethylamino)naphthalene cations. In the (8‐dimethylamino‐1‐napthyl)dimethylammonium cat­ion, a strong disordered intramolecular hydrogen bond is formed with N?N = 2.589 (3) Å. The geometry and occupancy obtained in the final restrained refinement suggest that the disordered hydrogen bond may be asymmetric. Water mol­ecules link the anion dimers into infinite chains via hydrogen bonding.     

1,8‐Bis[(dimethoxy)phosphino]naphthalene: A New Bis‐phosphonite Ligand with a Rigid C3‐Backbone and Unexpected Reaction Chemistry

1,8‐Bis[(diethylamino)phosphino]naphthalene ( 1 ) reacted with dry methanol in dichloromethane to form the new bis‐phosphonite ligand 1,8‐bis[(dimethoxy)phosphino]naphthalene (dmeopn, 2 ). By oxidation of 2 with H₂O₂ · (H₂N)₂C(:O) the corresponding bis‐phosphonate, 1,8‐bis[(dimethoxy)phosphoryl]naphthalene ( 3 ), was obtained quantitatively. Reaction of 3 with phosphorus trichloride unexpectedly furnished a 2.4 : 1 mixture of the bis‐phosphonate anhydrides rac‐ and meso‐1,3‐dimethoxy‐1,3‐dioxo‐2,3‐dihydro‐1,3‐diphospha‐2‐oxaphenalene (rac‐ 4 and meso‐ 4 ) from which rac‐ 4 could be fractionally crystallised. The bis‐phosphonite 2 behaved as a normal bidentate chelate ligand towards Mo⁰ and Pd^II, and furnished the complexes [(dmeopn)Mo(CO)₄] ( 5 ) and [(dmeopn)PdCl₂] ( 6 ) when treated with [(nor)Mo(CO)₄] or [(cod)PdCl₂] (nor = norbornadiene, cod = cycloocta‐1,8‐diene). Attempts to prepare 1,8‐diphosphinonaphthalene ( 7 ) by reducing 2 or 3 with LiAlH₄ or LiAlH₄/TMSCl (1 : 1) (TMSCl = trimethyl chlorosilane) in THF led to inseparable mixtures of phosphorus‐containing products. Compounds 2 – 6 were characterised by ¹H‐, ¹³C‐, and ³¹P‐NMR spectroscopy, IR spectroscopy, mass spectrometry and elemental analysis. X‐ray crystal structure analyses were carried out for the bis‐phosphonate anhydride rac‐ 4 and the palladium(II) complex 6 . The geometry of compound rac‐ 4 , in which the phosphorus atoms are connected by an oxygen atom, reveals a relief of strain from the bis‐phosphine 1 , whereas the 1,8‐P,P′‐naphthalenediyl group in 6 is surprisingly distorted; the P atoms are displaced from the naphthalene best plane by –46.7 and 54.5 pm.     

Poly[μ‐aqua‐μ4‐naphthalene‐1,8‐dicarboxylato‐zinc(II)]

In the title complex, [Zn(C₁₂H₆O₄)(H₂O)]_n, a Zn^II polymer based on naphthalene‐1,8‐dicarboxylate (1,8‐nap), the Zn^II atoms adopt an elongated octahedral coordination geometry. A zigzag chain is formed by μ₂‐aqua ligands and μ₂‐carboxylate groups of the 1,8‐nap ligands. Adjacent parallel chains are further linked by 1,8‐nap ligands, forming a twisted two‐dimensional layer structure along the (100) plane.     

Beryllium‐Based Anion Sponges: Close Relatives of Proton Sponges

Through the use of high‐level ab initio and density functional calculations it is shown that 1,8‐diBeX‐naphthalene (X=H, F, Cl, CN, CF₃, C(CF₃)₃) derivatives behave as anion sponges, very much as 1,8‐bis(dimethylamino)naphthalene derivatives behave as proton sponges. The electron‐deficient nature of the BeX substituents, which favors strong charge transfer from the anion towards the former, results in anion affinities that are among the largest ones reported for single neutral molecules.     

Comparative structural analysis of 2,7‐diethoxy‐1,8‐bis(4‐phenoxybenzoyl)naphthalene and its homologues: orientation of the 4‐phenoxybenzoyl groups at the 1‐ and 8‐positions of the naphthalene ring

The title molecule, C₄₀H₃₂O₆, possesses crystallographically imposed twofold symmetry, with the central two C atoms of the naphthalene unit sited on the rotation axis. The two 4‐phenoxybenzoyl groups in the molecule are twisted away from the attached naphthalene unit, with a torsion angle of 66.76 (15)° between the naphthalene unit and the carbonyl group (C—C—C=O), and are oriented in mutually opposing directions (anti orientation). There is an apparent difference in the conformations of the 4‐phenoxybenzoyl groups at the 1‐ and 8‐positions of the naphthalene ring between the title molecule and its methoxy‐bearing homologue [Hijikata et al. (2010). Acta Cryst. E 66 , o2902–o2903]. Whilst the 4‐phenoxybenzoyl groups in 2,7‐diisopropoxy‐1,8‐bis(4‐phenoxybenzoyl)naphthalene [Yoshiwaka et al. (2013). Acta Cryst. E 69 , o242] are situated in the same anti orientation as the title molecule, those of 2,7‐dimethoxy‐1,8‐bis(4‐phenoxybenzoyl)naphthalene are oriented in the same direction with respect to the naphthalene ring system, i.e. in a syn orientation.     

N‐(2‐Bromoethyl)‐4‐piperidino‐1,8‐naphthalimide and N‐(3‐bromopropyl)‐4‐piperidino‐1,8‐naphthalimide

N‐(2‐Bromoethyl)‐4‐piperidino‐1,8‐naphthalimide, C₁₉H₁₉BrN₂O₂, (I), and N‐(3‐bromopropyl)‐4‐piperidino‐1,8‐naphthalimide, C₂₀H₂₁BrN₂O₂, (II), are an homologous pair of 1,8‐naphthalimide derivatives. The naphthalimide units are planar and each piperidine substituent adopts a chair conformation. This study emphasizes the importance of π‐stacking interactions, often augmented by other contacts, in determining the crystal structures of 1,8‐naphthalimide derivatives.     

An Exceedingly Mild,Green Synthesis of Substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amine Derivatives and Their Antimicrobial Activity

An exceedingly and highly efficient procedure has been described for the synthesis of substituted N‐3‐diaryl‐1,8‐naphthyridin‐2‐amines by the reaction of 2‐chloro‐3‐aryl‐1,8‐naphthyridines with various anilines in the presence of N‐methyl‐2‐pyrrolidone and K₂CO₃ under thermal green solvent‐free conditions. The significant features of this green reaction include very good yields in purity, simple experimental, short reaction time, easy workability, and avoidance of toxic solvents. All synthesized compounds have been evaluated for their antibacterial activity.     

Synthesis of the Anticodon Hairpin tRNAfMet Containing N‐{[9‐(β‐D‐Ribofuranosyl)‐9H‐purin‐6‐yl]carbamoyl}‐L‐threonine (=N6‐{{[(1S,2R)‐1‐Carboxy‐2‐hydroxypropyl]amino}carbonyl}adenosine,t6A)

As part of our studies on the structure of yeast ^tRNA_f^Met, we investigated the incorporation of N‐{[9‐(β‐D ‐ribofuranosyl)‐9H‐purin‐6‐yl]carbamoyl}‐L ‐threonine (t⁶A) in the loop of a RNA 17‐mer hairpin. The carboxylic function of the L ‐threonine moiety of t⁶A was protected with a 2‐(4‐nitrophenyl)ethyl group, and a (tert‐butyl)dimethylsilyl group was used for the protection of its secondary OH group. The 2′‐OH function of the standard ribonucleotide building blocks was protected with a [(triisopropylsilyl)oxy]methyl group. Removal of the base‐labile protecting groups of the final RNA with 1,8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) and then with MeNH₂ was done under carefully controlled conditions to prevent hydrolysis of the carbamate function, leading to loss of the L ‐threonine moiety.     

On the P‐Coordinating Limit of NHC–Phosphenium Cations toward RhI Centers

Two types of imidazoliophosphane with additional electron‐withdrawing substituents, such as alkoxy or imidazolio groups, are experimentally described and theoretically studied. Diethyl N,N′‐2,4,6‐methyl(phenyl)imidazoliophosphonite is shown to retain a P‐coordinating ability toward a {RhCl(cod)} (cod=cycloocta‐1,5‐diene) center, thus competing with the cleavage of the labile C? P bond. Derivatives of N,N′‐phenylene‐bridged diimidazolylphenylphosphane were isolated in good yield. Whereas the dicationic phosphane proved to be inert in the presence of [{RhCl(cod)}₂], the monocationic counterpart was shown to retain the P‐coordinating ability toward a {RhCl(cod)} center, thus competing with the N‐coordinating ability of the nonmethylated imidazolyl substituent. The ethyl phosphinite version of the dication, thus possessing an extremely electron‐poor P^III center, was also characterized. According to the difference between the calculated homolytic and heterolytic dissociation energies, the N₂C???P bond of imidazoliophosphanes with aryl, amino, or alkoxy substituents on the P atom is shown to be of dative nature. The P‐coordinating properties of imidazoliophosphanes with various combinations of phenyl or ethoxy substituents on the P atom and those of six diimidazolophosphane derivatives with zero, one, or two methylium substituents on the N atom, were analyzed by comparison of the corresponding HOMOs and LUMOs and by calculation of the IR C?O stretching frequencies of their [RhCl(CO)₂] complexes. Comparison of the ν_CO values allows the family of the electron‐poor Im⁺PRR′ (Im=imidazolyl) potential ligands to be ranked in the following order versus (R,R′): P(OEt)₃<(Ph,Ph)<(Ph,OEt)<(OEt,OEt)<PF₃<(Ph,Im)<(Ph,Im⁺)<(OEt,Im⁺). The (Ph,Im) representative is therefore the least electron‐donating phosphane for which coordinating behavior toward a Rh^I center has been experimentally evidenced to date. Ultimate applications in catalysis could be envisaged.     

Pyridyl‐Functionalised 3H‐1,2,3,4‐Triazaphospholes: Synthesis,Coordination Chemistry and Photophysical Properties of Low‐Coordinate Phosphorus Compounds

Novel conjugated, pyridyl‐functionalised triazaphospholes with either tBu or SiMe₃ substituents at the 5‐position of the N₃PC heterocycle have been prepared by a [3+2] cycloaddition reaction and compared with structurally related, triazole‐based systems. Photoexcitation of the 2‐pyridyl‐substituted triazaphosphole gives rise to a significant fluorescence emission with a quantum yield of up to 12 %. In contrast, the all‐nitrogen triazole analogue shows no emission at all. DFT calculations indicate that the 2‐pyridyl substituted systems have a more rigid and planar structure than their 3‐ and 4‐pyridyl isomers. Time‐dependent (TD) DFT calculations show that only the 2‐pyridyl‐substituted triazaphosphole exhibits similar planar geometry, with matching conformational arrangements in the lowest energy excited state and the ground state; this helps to explain the enhanced emission intensity. The chelating P,N‐hybrid ligand forms a Re^I complex of the type [(N^N)Re(CO)₃Br] through the coordination of nitrogen atom N² to the metal centre rather than through the phosphorus donor. Both structural and spectroscopic data indicate substantial π‐accepting character of the triazaphosphole, which is again in contrast to that of the all‐nitrogen‐containing triazoles. The synthesis and photophysical properties of a new class of phosphorus‐containing extended π systems are described.     

N‐Arylation of Diketopyrrolopyrroles with Aryl Triflates

A new methodology for the double N‐arylation of diketopyrrolopyrroles with aryl triflates has been developed. It is now possible to prepare diketopyrrolopyrroles bearing N‐substituents derived from naphthalene, anthracene and coumarin in two steps from commercially available phenols. This represents the first time arenes lacking strong electron‐withdrawing groups were inserted onto lactamic nitrogen atoms via arylation. The ability to incorporate heretofore unprecedented substituents translates to increased modulation of the resulting photophysical properties such as switching‐on/off solvatofluorochromism. TD‐DFT calculations have been performed to explore the nature of the relevant excited states. This new synthetic method made it possible to elucidate the influence of such substituents on the absorption and emission properties of tetraaryl substituted diketopyrrolopyrroles.     

Bis[μ3‐1,8‐bis(triisopropylsilylamido)naphthalene]bis(tetrahydrofuran)di‐μ3‐oxido‐dimanganese(III)disodium

The solid‐state structure of the title compound, [Na₂Mn₂(C₃₂H₅₆N₂OSi₂)₂O₂] or [1,8‐C₁₀H₆(NSiⁱPr₃)₂Mn(μ₃‐O)Na(THF)]₂, which lies across a crystallographic twofold axis, exhibits a central [Mn₂O₂Na₂]⁴⁺ core, with two oxide groups, each triply bridging between the two Mn^III ions and an Na⁺ ion. Additional coordination is provided to each Mn^III centre by a 1,8‐C₁₀H₆(NSiⁱPr₃)₂ [1,8‐bis(triisopropylsilylamido)naphthalene] ligand and to the Na⁺ centres by a tetrahydrofuran molecule. The presence of an additional Na...H—C agostic interaction potentially contributes to the distortion around the bridging oxide group.     

New rac‐XP(O)(OC6H5)(NHC6H4‐p‐CH3) [X = N(CH3)(cyclo‐C6H11) and NH(C3H5)] and rac‐(C6H5CH2NH)P(O)(OC6H5)(NH‐cyclo‐C6H11) mixed‐amide phosphinates

The mixed‐amide phosphinates, rac‐phenyl (N‐methylcyclohexylamido)(p‐tolylamido)phosphinate, C₂₀H₂₇N₂O₂P, (I), and rac‐phenyl (allylamido)(p‐tolylamido)phosphinate, C₁₆H₁₉N₂O₂P, (II), were synthesized from the racemic phosphorus–chlorine compound (R,S)‐(Cl)P(O)(OC₆H₅)(NHC₆H₄‐p‐CH₃). Furthermore, the phosphorus–chlorine compound ClP(O)(OC₆H₅)(NH‐cyclo‐C₆H₁₁) was synthesized for the first time and used for the synthesis of rac‐phenyl (benzylamido)(cyclohexylamido)phosphinate, C₁₉H₂₅N₂O₂P, (III). The strategies for the synthesis of racemic mixed‐amide phosphinates are discussed. The P atom in each compound is in a distorted tetrahedral (N¹)P(=O)(O)(N²) environment. In (I) and (II), the p‐tolylamido substituent makes a longer P—N bond than those involving the N‐methylcyclohexylamido and allylamido substituents. In (III), the differences between the P—N bond lengths involving the cyclohexylamido and benzylamido substituents are not significant. In all three structures, the phosphoryl O atom takes part with the N—H unit in hydrogen‐bonding interactions, viz. an N—H...O=P hydrogen bond for (I) and (N—H)(N—H)...O=P hydrogen bonds for (II) and (III), building linear arrangements along [001] for (I) and along [010] for (III), and a ladder arrangement along [100] for (II).     

Di‐μ‐chloro‐bis({2‐[N,N‐bis(2‐aminoethyl)amino‐κ3N]ethylaminium}copper(II)) bis(naphthalene‐1,5‐disulfonate) pentahydrate

The title compound, [Cu₂(C₆H₁₉N₄)₂Cl₂](C₁₀H₆O₆S₂)₂·5H₂O, is comprised of discrete [Cu₂(tren)₂Cl₂]²⁺ dimers {tren is 2‐[N,N‐bis(2‐amino­ethyl)­amino]­ethyl­aminium} and naphthalene‐1,5‐di­sulfonate anions. Two Cl^? anions bridge two Cu^II ions, each of which is also coordinated by two of the primary and the tertiary amino N atoms of the tren ligand, giving each metal atom a distorted square‐pyramidal coordination geometry. The cation lies about an inversion centre and the asymmetric unit also has two independent anions lying about inversion centres.     

Four‐, five‐ and six‐coordinated transition metal complexes based on naphthalimide Schiff base ligands: Synthesis,crystal structure and properties

Two bidentate Schiff base ligands (HL¹ = N‐n‐butyl‐4‐[(E)‐2‐(((2‐aminoethyl)imino)methyl)phenol]‐1,8‐naphthalimide; and HL² = N‐n‐butyl‐4‐[(E)‐2‐(((2‐aminoethyl)imino)methyl)‐6‐methoxyphenol]‐1,8‐naphthalimide) with their metal complexes [Cu(L¹)₂] ( 1 ), [Zn(L¹)₂(Py)]₂?H₂O ( 2 ) and [Ni(L²)₂(DMF)₂] ( 3 ) have been synthesized and characterized. Single‐crystal X‐ray structure analysis reveals that complex 1 has a four‐coordinated square geometry, while complex 2 is a five‐coordinated square pyramidal structure and complex 3 is a distorted six‐coordinated octahedral structure. Cyclic voltammograms of 1 indicate an irreversible Cu²⁺/Cu⁺ couple. In vitro antioxidant activity assay demonstrates that the ligands and the two complexes 1 and 3 display high scavenging activity against hydroxyl (HO^?) and superoxide (O₂^??) radicals. Moreover, the fluorescence properties of the ligands and complexes 1 – 3 were studied in the solid state. Metal‐mediated enhancement is observed in 2 , whereas metal‐mediated fluorescence quenching occurs with 1 and 3 .     

A Zwitterionic Phosphonio‐1, 2, 4‐Diazaphospholide and Neutral 1, 2, 4‐Diazaphosphole — A Comparative Study of Molecular Structures and Co‐ordination Properties

The bis‐phosphonio‐1, 2, 4‐diazaphospholide salt ( 1 [Cl]) reacts with complex boron hydrides under selective extrusion of one PPh₃ moiety to give borane adducts of a novel zwitterionic phosphonio‐1, 2, 4‐diazaphospholide. Both the Et₃B adduct 2b and the free zwitterionic heterocycle 3 , which was liberated by further reaction of 2b with NEt₃, were characterized by spectroscopic data and 2b , as well, by a single crystal X‐ray diffraction study. The comparison of the structural data with those of a neutral 1, 2, 4‐diazaphosphole and a lithium‐1, 2, 4‐diazaphospholide which was formed by deprotonation of the parent 1, 2, 4‐diazaphosphole 4a discloses trends in endocyclic bonding distances which can be rationalized in terms of a charge dependent shift in the π‐electron distribution. First studies of the co‐ordination properties reveal for both 2b and 4a a marked preference to bind two M(CO)₅‐fragments (M = Cr, W) via the lone‐pairs of the phosphorus and one nitrogen atom; mononuclear complexes with P‐co‐ordinated heterocycles are formed as intermediates. A single crystal X‐ray diffraction study of the dinuclear complex [Cr₂(CO)₁₀(μ₂‐C₂H₃N₂P‐κP, κN)] ( 10a ) together with spectroscopic studies (including ¹⁸³W NMR studies of tungsten complexes) suggests that M→L back donation is more efficient for P‐ than for N‐bound metal fragments. No evidence for π‐co‐ordination of the 1, 2, 4‐diazaphosphole ring to a Cr(CO)₃ fragment was obtained.     

Defluorinative C(sp3)−P Bond Construction for the Synthesis of Phosphorylation gem‐Difluoroalkenes under Catalyst‐ and Oxidant‐Free Conditions

Defluorinative C(sp³)?P bond formation of α‐trifluoromethyl alkenes with phosphine oxides or phosphonates have been achieved under catalyst‐ and oxidant‐free conditions, giving phosphorylation gem‐difluoroalkenes as products. α‐Trifluoromethyl alkenes bearing various of aryl substituents such as halogen, cyano, ester and heterocyclic groups are available in this transformation. The results of control experiments demonstrated that the mechanism of dehydrogenative/defluorinative cross‐coupling reactions was not a radical route, but might be an S_N2′ process involving phosphine oxide anion.     

Effect of ligand backbone substituents of nickel α‐diimine complexes on livingness/controllability of olefin polymerization: Competition between monomer isomerization and propagation

Four α‐diimine nickel complexes [(Ar? N?C(R)? C(R)?N? Ar)NiBr₂; R?H, CH₃, cyclohexane‐1,2‐diyl, naphthalene‐1,8‐diyl, Ar?2,6‐i‐Pr₂‐C₆H₃‐) were investigated in propene and hex‐1‐ene polymerization to identify the limits of backbone substituent R size needed to provide living/controlled α‐olefins polymerization by the sufficient suppression of β–H elimination transfer. Propagation kinetics measurements, molar mass on monomer conversion dependencies and reinitiation tests were used to evaluate the livingness of hex‐1‐ene polymerization. Interestingly, living/controlled hex‐1‐ene polymerization was observed in the case of all diimine derivatives including the one bearing only hydrogen atom in backbone positions. Unexpectedly, in the case of catalysts bearing H and CH₃ backbone substituents, we observed the unusual isomerization of hex‐1‐ene into internal hexenes in parallel with its polymerization. Nevertheless, by subtracting the amount of monomer consumed in isomerization side reaction, polymerization still keeps the features of living/controlled process. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3193–3202