Bis(2‐aminopyridinium) maleate

Two cyclic eight‐membered hydrogen‐bonded rings exist in the title compound, 2C₅H₇N₂⁺·C₄H₂O₄²⁻, involving the 2‐amino­pyridinium and maleate ions. The dihedral angle between the two pyridinium rings hydrogen bonded to the maleate ion is 74.80 (4)°. The maleate anion lies on a twofold axis and is linked to the pyridinium cations by intermolecular N—H⃛O hydrogen bonds. The heterocycle is fully proton­ated, which enables amino–imino tautomerization.     

1,4‐Bis(p‐tolyl­ethynyl)benzene

The rod‐like molecule of the title hydro­carbon, C₂₄H₁₈, is centrosymmetric, with the centroid of the central benzene ring residing on an inversion center. The molecules display a planar conformation of the benzene rings and aggregate into stacks along the [010] direction via Csp³—H⋯π(arene) interactions, thus forming a stair‐like pseudo‐two‐dimensional network. Each molecule acts as both a C—H hydrogen donor and a π‐arene acceptor, forming four hydrogen bonds per molecule.     

Crystallographic report: Bis(η5‐methyl‐cyclopentadienyl)‐bis(cyanato)‐vanadium(IV)

The crystal structure of the first cyclopentadienyl vanadium(IV) pseudohalide complex, (η⁵‐C₅H₄CH₃)₂V(NCO)₂, was determined. The molecule has a typical bent metallocene structure in which two η⁵‐bonded methyl‐cyclopentadienyl rings and two nitrogen atoms of cyanato ligands occupy the pseudotetrahedral coordination sites around the vanadium(IV) center. Copyright © 2005 John Wiley & Sons, Ltd.     

Synthesis and Redox Properties of Bis{4‐[bis(4‐methoxyphenyl)amino]‐2,6‐bis(2,4,6‐triisopropylphenyl)phenyl}diphosphene

Bis{4‐[bis(4‐methoxyphenyl)amino]‐2,6‐bis(2,4,6‐triisopropylphenyl)phenyl}diphosphene ( 1 ), possessing two bis(4‐methoxyphenyl)amino groups as redox sites as well as electron‐donating sources, was synthesized and isolated as a red solid. The cyclic voltammogram of 1 at −78° consisted of three reversible redox waves corresponding to two‐step oxidation of the triarylamine moieties and reduction of the diphosphene moiety. Introduction of the two amino groups also contributed to a red shift of the absorption maximum in the UV/VIS spectrum, which was responsible for the intense red color of 1 .     

4‐Aminopyridinium 4‐aminobenzoate dihydrate and 4‐aminopyridinium nicotinate

In the title compounds, 4‐aminopyridinium 4‐aminobenzoate dihydrate, C₇H₆NO₂⁻·C₅H₇N₂⁺·2H₂O, (I), and 4‐aminopyridinium nicotinate, C₅H₇N₂⁺·C₆H₄NO₂⁻, (II), the aromatic N atoms of the 4‐aminopyridinium cations are protonated. In (I), the asymmetric unit is composed of two 4‐aminopyridinium cations, two 4‐aminobenzoate anions and four water molecules, and the compound crystallizes in a noncentrosymmetric space group. The two sets of independent molecules of (I) are related by a centre of symmetry which is not part of the space group. In (I), the protonated pyridinium ring H atoms are involved in bifurcated hydrogen bonding with carboxylate O atoms to form an R₁²(4) ring motif. The water molecules link the ions to form a two‐dimensional network along the (10) plane. In (II), an intramolecular bifurcated hydrogen bond generates an R₁²(4) ring motif and inter‐ion hydrogen bonding generates an R₄²(16) ring motif. The packing of adduct (II) is consolidated via N—H...O and N—H...N hydrogen bonds to form a two‐dimensional network along the (10) plane.     

Synthesis of poly(p‐phenylene sulfide) from bis(4‐bromophenyl) disulfide

Improved reaction conditions for the preparation of poly(p‐phenylene sulfide) (PPS) directly from bis(4‐bromophenyl) disulfide (BBD) have been established. Heating BBD with magnesium metal afforded only a low molecular weight polymer. PPS with a melting temperature around 280 °C was obtained from BBD in the presence of sodium carbonate or zinc metal. The best results were obtained with the addition of a catalytic amount of KI to the zinc–BBD mixture. Polymers prepared by the above methods are semicrystalline and dissolve in 1‐chloronaphthalene and have properties comparable to commercial PPS. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 900–904, 2006     

Picolinamidium squarate and di‐p‐toluidinium squarate dihydrate

The crystal structure determinations of picolinamidium squarate, C₆H₇N₂O⁺·C₄O₄⁻, (I), and di‐p‐toluidinium squarate dihydrate, 2C₇H₁₀N⁺·C₄O₄²⁻·2H₂O, (II), are reported. While salt formation occurs by donation of one H atom from squaric acid to the picolin­amide mol­ecule in (I), in compound (II), each squaric acid mol­ecule donates one H atom to the p‐toluidine N atom of two trans p‐toluidine molecules. In (I), the pyridine ring is coplanar with the squarate monoanion through imposed crystallographic mirror symmetry; in (II), the dihedral angle between the p‐toluidine moiety and the squarate dianion is 70.71 (1)°. In (I), a three‐dimensional structure is formed via van der Waals interactions between parallel planes of mol­ecules, with hydrogen‐bond interactions (N—H⋯O and O—H⋯O) acting within the planes; hydrogen bonds form a three‐dimensional network in (II).     

Bis(2,5‐dimethoxy‐4‐methylphenyl)methane and bis(2,5‐dimethoxy‐3,4,6‐trimethylphenyl)methane

Bis(2,5‐di­methoxy‐4‐methyl­phenyl)­methane, C₁₉H₂₄O₄, (IIa), was obtained and characterized as a minor product from the reaction of tolu­hydro­quinone di­methyl ether (1,4‐dimethoxy‐2‐methylbenzene) with N‐(hydroxy­methyl)­tri­fluoro­acet­amide. Similarly, bis(2,5‐di­methoxy‐3,4,6‐tri­methyl­phenyl)­methane, C₂₃H₃₂O₄, (IIb), was prepared from the corresponding reaction of tri­methyl­hydro­quinone di­methyl ether (2,5‐dimethoxy‐1,3,4‐trimethylbenzene). The mol­ecules of (IIa) and (IIb) each lie on a twofold axis passing through the methyl­ene group. The dihedral angle between the planar phenyl rings is 73.4 (1)° in (IIa) and 77.9 (1)° in (IIb). The external bond angles around the bridging methyl­ene group are 116.6 (2) and 117.3 (2)° for (IIa) and (IIb), respectively. In (IIa), the methoxy substituents lie in the plane of the ring and are conjugated with the aromatic system, whereas in (IIb), they are almost perpendicular to the phenyl ring and are positioned on opposite sides.     

Crystallographic report: Bis(4‐nitrobenzoato)bis(pyridine)zinc(II)

The molecular structure of [Zn(O₂CC₆H₄NO₂‐p)₂(pyridine)₂] exhibits a distorted N₂O₂ tetrahedral geometry around the zinc atom owing to the presence of monodentate p‐nitrobenzoate ligands; the molecule has twofold symmetry. Copyright © 2004 John Wiley & Sons, Ltd.     

Crystallographic report: Bis[bis(N,N‐diethyldithiocarbamato)zinc(II)] (trans‐1,2‐bis(4‐pyridyl)ethylene)trans‐1, 2‐bis(4‐pyridyl)ethylene lattice adduct

The dimeric and centrosymmetric structure of [Zn(S₂CNEt₂)₂(trans‐NC₅H₄C(H)?C(H)C₅H₄N)]₂ shows bidentate coordination by the dithiocarbamate ligands and a distorted square pyramidal geometry for zinc, defined by a NS₄ donor set with the N atom in the apical position. The compound co‐crystallises with a centrosymmetric molecule of trans‐NC₅H₄C(H)?C(H)C₅H₄N that does not form a significant interaction to the Zn atom. Copyright © 2003 John Wiley & Sons, Ltd.     

2,6‐Bis[bis(2‐pyridiniomethyl)aminomethyl]‐4‐tert‐butylphenol dichloride diperchlorate hydrate

The title compound, C₃₆H₄₄N₆O⁴⁺·2Cl^?·2ClO₄^?·0.132H₂O, is shown to be protonated at all the pyridine N atoms; the two chloride ions are hydrogen bonded to three pyridine N atoms and to the phenolic O atom of the same cation [Cl?N = 3.045 (2)–3.131 (2) Å and Cl?O = 2.938 (2) Å], and the remaining pyridine N atom is hydrogen bonded to the phenolic O atom [N?O = 2.861 (2) Å]. The mean value of the C—N—C angle of the protonated pyridine rings is 123.4 (1)°, which is significantly larger than that found for unprotonated pyridine rings.     

Crystallographic report: Bis[3‐(tri‐p‐tolyl)germyl‐3‐(o‐tolyl)‐propionato]dibutyltin(IV)

The crystal structure of [(p‐CH₃C₆H₄)₃GeCH(o‐CH₃C₆H₄)CH₂CO₂]₂Sn(C₄H₉)₂ consists of a monomer with the atoms of tin and germanium both occupying tetrahedral geometries. However, the tin atom is distorted towards a skew trapezoidal bipyramid geometry as a result of weakly chelating carboxylate ligands. Copyright © 2003 John Wiley & Sons, Ltd.     

Bis(μ‐4‐carboxy‐2‐sulfonatobenzoato)bis[aqua(2,2′‐bipyridyl)manganese(II)]

In the title compound, [Mn₂(C₈H₄O₇S)₂(C₁₀H₈N₂)₂(H₂O)₂], pairs of hexacoordinated manganese(II) centres are bridged by 2‐sulfonatoterephthalate(2−) anions to form cyclic centrosymmetric dimers, which are linked into sheets by O—H...O hydrogen bonds.     

trans‐Tetra­chloro­bis(4‐methyl­pyridine)­germanium(IV)

The structure of the title compound, [GeCl₄(C₆H₇N)₂], (I), is the first example of an addition compound of GeCl₄ with two aromatic nitro­gen bases. The mol­ecule, with essential D_2h symmetry, has crystallographic C_2h symmetry. The environment around the Ge atom can be described as a slightly distorted octahedron with the 4‐methyl­pyridine ligands occupying axial positions and the four chloro ligands in the equatorial plane. The structure of (I) is isomorphous with the corresponding silicon halides.     

Binuclear dichlorido(η6‐p‐cymene)ruthenium(II) complexes with bis(nicotinate)‐ and bis(isonicotinate)‐polyethylene glycol ester ligands

Neutral binuclear ruthenium complexes 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 of the general formula [{RuCl₂(η⁶‐p‐cym)}₂ μ‐(N^∩N)] (N^∩N = bis(nicotinate)‐ and bis(isonicotinate)‐polyethylene glycol esters: (3‐py)COO(CH₂CH₂O)_nCO(3‐py) and (4‐py)COO(CH₂CH₂O)_nCO(4‐py), n =1–4), as well as mononuclear [RuCl₂(η⁶‐p‐cym)((3‐py)COO(CH₂CH₂OCH₃)‐κN)], complex 9 , were synthesized and characterized using elemental analysis and electrospray ionization high‐resolution mass spectrometry, infrared, ¹H NMR and ¹³C NMR spectroscopies. Stability of the binuclear complexes in the presence of dimethylsulfoxide was studied. Furthermore, formation of a cationic complex containing bridging pyridine‐based bidentate ligand was monitored using ¹H NMR spectroscopy. Ligand precursors, polyethylene glycol esters of nicotinic ( L1 · 2HCl– L4 · 2HCl and L9 · HCl) and isonicotinic acid dihydrochlorides ( L5 · 2HCl– L8 · 2HCl), binuclear ruthenium(II) complexes 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 and mononuclear complex 9 were tested for in vitro cytotoxicity against 518A2 (melanoma), 8505C (anaplastic thyroid cancer), A253 (head and neck tumour), MCF‐7 (breast tumour) and SW480 (colon carcinoma) cell lines. Copyright © 2014 John Wiley & Sons, Ltd.     

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.     

Three p‐xylene‐solvated pseudopolymorphs of bis[1,3‐bis(pentafluorophenyl)propane‐1,3‐dionato]copper(II)

The Cu²⁺ ions in the title compounds, namely bis[1,3‐bis(pentafluorophenyl)propane‐1,3‐dionato‐κ²O,O′]copper(II) p‐xylene n‐solvate, [Cu(C₁₅HF₁₀O₂)₂]·nC₈H₁₀, with n = 1, (I), n = 2, (II), and n = 4, (III), are coordinated by two 1,3‐bis(pentafluorophenyl)propane‐1,3‐dionate ligands. The coordination complexes of (I) and (II) have crystallographic inversion symmetry at the Cu atom and the p‐xylene molecule in (I) also lies across an inversion centre. The p‐xylene molecules in (I) and (II) interact with the pentafluorophenyl groups of the complex via arene–perfluoroarene interactions. In the crystal of (III), two of the p‐xylene molecules interact with the pentafluorophenyl groups via arene–perfluoroarene interactions. The other two p‐xylene molecules are located on the CuO₄ coordination plane, forming a uniform cavity produced by metal...π interactions.     

Bis(μ4‐butane‐1,4‐dithiolato)bis[hexacarbonyldiiron(II)(Fe—Fe)]

The novel title double‐butterfly Fe/S cluster complex, [Fe₄(C₄H₈S₂)₂(CO)₁₂], which is structurally similar to the active site of the Fe‐only hydrogenases, contains two inversion‐related Fe₂S₂(CO)₆ subcluster cores connected by two equivalent butyl chains to afford a 16‐membered macrocycle. The formation of the 16‐membered macrocycle has an influence on the C—S—Fe angles, while the Fe—Fe and Fe—S bond lengths remain similar to those in related complexes.     

Bis(μ‐phenyl 2‐pyridyl ketone N4,N4‐butane‐1,4‐diylthiosemicarbazonato)bis[chlorocopper(II)]

The title compound, [Cu₂(C₁₇H₁₇N₄S)₂Cl₂], exhibits a dimeric structure related by a centre of symmetry. The monomers are linked to each other by the longest Cu—S apical distance observed to date among Cu^II square‐pyramidal complexes of N⁴‐substituted thio­semicarbazones. Each Cu^II atom deviates from the coordination square plane, which contains the pyrid­yl and imine N atoms, the thiol­ate S atom and the Cl⁻ anion, towards the S atom of the adjacent monomer. The dimers pack in a zigzag manner through the crystal.     

Crystallographic report: Bis(µ2‐chloro)‐{bis(diethylether)‐lithium}‐bis(η5‐pentamethyl‐cyclopentadienyl)samarium(III)

The structure is mononuclear with samarium bound by two η⁵‐cyclopentadienyl ligands and two chloride ligands, the latter of which bridge to a doubly ether‐solvated lithium centre. Copyright © 2004 John Wiley & Sons, Ltd.