N‐{3‐[(2‐Ammonioethyl)amino]propyl}ethane‐1,2‐diaminium tris(trifluoromethanesulfonate): a salt of a folded triply protonated tetramine

The structure of a trifluoromethanesulfonate salt of a nontypical triply protonated linear tetramine, C₇H₂₃N₄³⁺·3CF₃SO₃⁻, with a layered crystal structure is presented. One N atom remains unprotonated. The conformation of the cation is enforced by intra‐ and intermolecular hydrogen bonds. The crystal structure is built of ca 10 Å deep layers, within which cations and anions are hydrogen bonded. Each layer is only weakly bound to its neighbours. This study shows a rare example of an unsymmetrically protonated polyamine and the relation between the lack of protonation, intramolecular hydrogen bonding and the conformation of the cation.     

N‐{4‐Bromo‐2‐[(3‐bromo‐1‐phenylsulfonyl‐1H‐indol‐2‐yl)methyl]‐5‐methoxyphenyl}acetamide

In the title compound, C₂₄H₂₀Br₂N₂O₄S, the indole ring system is planar and the S atom has a distorted tetrahedral configuration. The sulfonyl‐bound phenyl ring is orthogonal to the indole ring system and the conformation of the phenyl­sulfonyl substituent with respect to the indole moiety is influenced by intramolecular C—H⃛O hydrogen bonds involving the two sulfonyl O atoms. The mean plane through the acetyl­amido group makes a dihedral angle of 57.0 (1)° with the phenyl ring of the benzyl moiety. In the crystal, glide‐related mol­ecules are linked together by N—H⃛O hydrogen bonds and C—H⃛π interactions to form molecular chains, which extend through the crystal. Inversion‐related chains are interlinked by C—H⃛π interactions to form molecular layers parallel to the bc plane. These layers are interconnected through π–π interactions involving the five‐ and six‐membered rings of the indole moiety.     

Λ‐{1,4,7,10‐Tetrakis­[(S)‐2‐hydroxy­propyl‐κO]‐1,4,7,10‐tetra­aza­cyclo­do­decane‐κ4N}cadmium(II) bis(2,4,6‐tri­nitro­phenolate) aceto­nitrile solvate

Crystallization of [Cd(S‐thpc12)](ClO₄)₂·H₂O {S‐thpc12 is 1,4,7,10‐tetrakis­[(S)‐2‐hydroxy­propyl]‐1,4,7,10‐tetra­aza­cyclo­do­decane} in the presence of two equivalents of sodium picrate monohydrate (sodium 2,4,6‐tri­nitro­phenolate monohydrate) diastereoselectively produces a neutral receptor complex, viz. the title compound, Λ‐[Cd(C₂₀H₄₄N₄O₄)](C₆H₂N₃O₇)₂·CH₃CN. In this complex, two picrate anions hydrogen bond, via their phenolate moieties, to the pendant hydroxyl groups of the receptor which, together with the four N atoms, themselves bond to Cd^II in an approximately cubic arrangement. One picrate anion hydrogen bonds to all four hydroxyl groups, one of which also acts as the sole hydrogen‐bond donor to the second picrate anion.     

Methyl 2‐benzamido‐4‐(3,4‐dimethoxyphenyl)‐5‐methylbenzoate and N‐{5‐benzoyl‐2‐[(Z)‐2‐methoxyethenyl]‐4‐methylphenyl}benzamide

Methyl 2‐benzamido‐4‐(3,4‐dimethoxyphenyl)‐5‐methylbenzoate, C₂₄H₂₃NO₅, (Ia), and N‐{5‐benzoyl‐2‐[(Z)‐2‐methoxyethenyl]‐4‐methylphenyl}benzamide, C₂₄H₂₁NO₃, (IIa), were formed via a Diels–Alder reaction of appropriately substituted 2H‐pyran‐2‐ones and methyl propiolate or (Z)‐1‐methoxybut‐1‐en‐3‐yne, respectively. Each of these cycloadditions might yield two different regioisomers, but just one was obtained in each case. In (Ia), an intramolecular N—H...O hydrogen bond closes a six‐membered ring. A chain is formed due to aromatic π–π interactions, and a three‐dimensional framework structure is formed by a combination of C—H...O and C—H...π(arene) hydrogen bonds. Compound (IIa) was formed not only regioselectively but also chemoselectively, with just the triple bond reacting and the double bond remaining unchanged. Compound (IIa) crystallizes as N—H...O hydrogen‐bonded dimers stabilized by aromatic π–π interactions. Dimers of (IIa) are connected into a chain by weak C—H...π(arene) interactions.     

Structural Variations and Molecular Dynamics of Rare‐Earth Metal Complexes with the N,N‐Bis(2‐{pyrid‐2‐yl}ethyl)hydroxylaminato Ligand

The reaction of the donor‐functionalised N,N‐bis(2‐{pyrid‐2‐yl}ethyl)hydroxylamine and [LnCp₃] (Cp=cyclopentadiene) resulted in the formation of bis(cyclopentadienyl) hydroxylaminato rare‐earth metal complexes of the general constitution [Ln(C₅H₅)₂{ON(C₂H₄‐o‐Py)₂}] (Py= pyridyl) with Ln=Lu ( 1 ), Y ( 2 ), Ho ( 3 ), Sm ( 4 ), Nd ( 5 ), Pr ( 6 ), La ( 7 ). These compounds were characterised by elemental analysis, mass spectrometry, NMR spectroscopy (for compounds 1 , 2 , 4 and 7 ) and single‐crystal X‐ray diffraction experiments. The complexes exhibit three different aggregation modes and binding motifs in the solid state. The late rare‐earth metal atoms (Lu, Y, Ho and Sm) form monomeric complexes of the formula [Ln(C₅H₅)₂{η²‐ON(C₂H₄‐η¹‐o‐Py)(C₂H₄‐o‐Py)}] ( 1 – 4 , respectively), in which one of the pyridyl nitrogen donor atoms is bonded to the metal atom in addition to the side‐on coordinating hydroxylaminato unit. The larger Nd³⁺ and Pr³⁺ ions in 5 and 6 make the hydroxylaminato unit capable of dimerising through the oxygen atoms. This leads to the dimeric complexes [(Ln(C₅H₅)₂{μ‐η¹:η²‐ON(C₂H₄‐o‐Py)₂})₂] without metal–pyridine bonds. Compound 7 exhibits a dimeric coordination mode similar to the complexes 5 and 6 , but, in addition, two pyridyl functions coordinate to the lanthanum atoms leading to the [(La(C₅H₅)₂{ON(C₂H₄‐o‐Py)}{μ‐η¹:η²‐ON(C₂H₄‐η¹‐o‐Py)})₂] complex. The aggregation trend is directly related to the size of the metal ions. The complexes with coordinative pyridine–metal bonds show highly dynamic behaviour in solution. The two pyridine nitrogen atoms rapidly change their coordination to the metal atom at ambient temperature. Variable‐temperature (VT) NMR experiments showed that this dynamic exchange can be frozen on the NMR timescale.     

tert‐Butyl N‐{2‐[N‐(N,N′‐dicyclohexyl­ureido­carbonyl­ethyl)­carbamoyl]prop‐2‐yl}carbamate

The title compound, C₂₅H₄₄N₄O₅, exhibits a turn with the main chain reversing direction, held together by an intramol­ecular N—H?O hydrogen bond. In the urea fragment, a notable amide C—N bond between the carboxyl C and the tertiary N atom shows marked single‐bond character [1.437 (2) Å]. The dihedral angle of the β‐alanyl residue, centrally located in the turn, is gauche [69.2 (2)°]. The packing is mediated by two intermolecular hydrogen bonds and van der Waals contacts involving the methyl moieties and the cyclo­hexyl rings.     

The six‐membered‐ring azomethine N‐((E)‐{5‐[(E)‐(pyridin‐3‐ylimino)methyl]thiophen‐2‐yl}methylidene)pyridin‐3‐amine

The title compound, C₁₆H₁₂N₄S, forms a three‐dimensional layered network structure via intermolecular hydrogen bonding and π‐stacking. The azomethine molecule adopts the thermodynamically stable E regioisomer and the pyridine substituents are antiperiplanar. The mean planes of the pyridine rings and the azomethine group to which they are connected are twisted by 27.27 (5) and 33.60 (5)°. The electrochemical energy gap of 2.3 eV based on the HOMO–LUMO energy difference is in agreement with the spectroscopically derived value.     

Dichlorido{2‐[(2,6‐diethylphenyl)iminomethyl]quinoline‐κ2N,N′}palladium(II) acetonitrile monosolvate

The title complex, [PdCl₂(C₂₀H₂₀N₂)]·CH₃CN, was synthesized by the reaction of 2‐[(2,6‐diethylphenyl)iminomethyl]quinoline with dichlorido(cycloocta‐1,5‐diene)palladium(II) in dry CH₂Cl₂. The Pd^II ion is coordinated by two N atoms of the bidentate quinoline ligand and by two chloride anions, generating a distorted square‐planar coordination geometry around the metal centre. There is a detectable trans influence for the chloride ligands. The crystal packing is characterized by π–π stacking between the quinoline rings. The use of acetonitrile as the crystallization solvent was essential for obtaining good‐quality crystals.     

Syntheses and Structures of Nitridorhenium(V) and Nitridotechnetium(V) Complexes with N,N‐[(Dialkylamino)(thiocarbonyl)]‐N′‐(2‐hydroxyphenyl)benzamidines

[MNCl₂(PPh₃)₂] complexes (M = Re, Tc) react with N‐[(dialkylamino)(thiocarbonyl)]‐N′‐(2‐hydroxyphenyl)benzamidines (H₂L¹) with formation of neutral, five‐coordinate nitrido complexes of the composition [MN(L¹)(PPh₃)]. The products have distorted square‐pyramidal coordination spheres with each a tridentate, double‐deprotonated benzamidine and a PPh₃ ligand in their basal planes.     

Bis(μ‐2‐{5‐[(pyridin‐4‐ylmethyl)sulfanyl]‐1,3,4‐oxadiazol‐2‐yl}phenolato)bis[(acetylacetonato)copper(II)]: a novel binuclear metallocycle

The new asymmetric ligand 2‐{5‐[(pyridin‐4‐ylmethyl)sulfanyl]‐1,3,4‐oxadiazol‐3‐yl}phenol (HL) has been used to synthesize the novel discrete title binuclear metallocycle, [Cu₂(C₁₄H₁₀N₃O₂S)₂(C₅H₇O₂)₂] or Cu₂L₂(acac)₂ (acac is acetylacetonate). Each Cu^II centre is five‐coordinate and adopts a square‐pyramidal geometry. Two ligands are connected by two Cu^II cations to form the dinuclear metallocycle, which lies across a crystallographic inversion centre. Discrete molecules are linked into a two‐dimensional structure through weak Cu...S, C—H...π and π–π interactions.     

N‐(2‐Hydroxypropyl)methacrylamide (HPMA) Copolymer‐Linked Nitroxides: Potential Magnetic Resonance Contrast Agents

N‐(2‐Hydroxypropyl)methacrylamide (HPMA) copolymer‐linked nitroxides were synthesized as macromolecular contrast agents for MR imaging. Molar relaxivities of HPMA copolymer‐linked nitroxides increased linearly in proportion to the number of nitroxides attached per gram of copolymer. HPMA copolymer‐linked nitroxides with 15, 20 and 30 mol‐% nitroxide exhibited higher relaxivities than gadolinium diethylenetriaminepentaacetic acid (Gd‐DTPA). These results demonstrate the potential of HPMA copolymer‐linked nitroxides as MR contrast agents for solid tumors.

Structure of HPMA copolymer‐linked nitroxides.     

2‐(1,3‐Dithian‐2‐yl)benzaldehyde and N‐{2‐[2‐(1,3‐dioxan‐2‐yl)phenoxy]­ethyl}phthalimide

The crystal structures of two elaborated‐porphyrin precursors have been determined. In the crystalline state, 2‐(1,3‐di­thian‐2‐yl)­benz­aldehyde, C₁₁H₁₂OS₂, has its di­thiane ring in a slightly distorted chair conformation. The mol­ecules pack in anti‐parallel chains. N‐{2‐[2‐(1,3‐Dioxan‐2‐yl)­phenoxy]­ethyl}­phthal­imide, C₂₀H₁₉NO₅, is in a folded conformation. The dihedral angle between the phthal­imide and phenyl planes is 80.07 (3)°. In the crystalline states, mol­ecules stack on top of one another.     

Cross‐Linked‐Polymer‐Supported N‐{2′‐[(Arylsulfonyl)amino][1,1′‐binaphthalen]‐2‐yl}prolinamide as Organocatalyst for the Direct Aldol Intermolecular Reaction under Solvent‐Free Conditions

A bottom‐up strategy was used for the synthesis of cross‐linked copolymers containing the organocatalyst N‐{(1R)‐2′‐{[(4‐ethylphenyl)sulfonyl]amino}[1,1′‐binaphthalen]‐2‐yl}‐D ‐prolinamide derived from 2 (Scheme 1). The polymer‐bound catalyst 5b containing 1% of divinylbenzene as cross‐linker showed higher catalyst activity in the aldol reaction between cyclohexanone and 4‐nitrobenzaldehyde than 5a and 5c . Remarkably, the reaction in the presence of 5b was carried out under solvent‐free, mild conditions, achieving up to 93% ee (Table 1). The polymer‐bound catalyst 5b was recovered by filtration and re‐used up to seven times without detrimental effects on the achieved diastereo‐ and enantioselectivities (Table 2). The catalytic procedure with polymer 5b was extended to the aldol reaction under solvent‐free conditions of other ketones, including functionalized ones, and different aromatic aldehydes (Table 3). In some cases, the addition of a small amount of H₂O was required to give the best results (up to 95% ee). Under these reaction conditions, the cross‐aldol reaction between aldehydes proceeded in moderate yield and diastereo‐ and enantioselectivity (Scheme 2).     

N‐[(R)‐1‐(2‐Hydr­oxy‐5‐methyl­phen­yl)­eth­yl]‐N‐[(R)‐1‐(2‐meth­oxy‐5‐methyl­phen­yl)‐2‐phenyl­eth­yl]aminium chloride

The title compound, C₂₅H₃₀NO₂⁺·Cl⁻, has been synthesized, and the crystal structure shows that it is mainly stabilized through inter­molecular N—H·Cl and O—H·Cl and intra­molecular N—H·O hydrogen bonds. The absolute configuration of the new stereogenic center (the C atom adjacent to the N atom on the phenol side) was determined to have an R configuration.     

Bis(2‐{1‐[(2,4,6‐trimethylphenyl)imino]ethyl}pyrrol‐1‐ido‐κ2N,N′)nickel(II): a supramolecular structure formed by C—H...π(arene) hydrogen bonds

<!?tlsb=‐0.2pt>Nitrogen‐based polydentate ligands are of interest owing to their flexible complexation to transition metal atoms. For the title compound, [Ni(C₁₅H₁₇N₂)₂], a transition metal complex formed by the coordination of two identical N,N′‐bidentate mono(imino)pyrrolyl ligands to an Ni^II centre, an X‐ray crystal diffraction study indicates that the two ligands show an inverted arrangement with respect to one another around the Ni^II centre, which is located on a crystallographic inversion centre. The planes of the aromatic substituents at the imine N atoms of the ligands show dihedral angles of 85.91 (5)° with respect to the NiN₄ plane. The Ni—N bond lengths are in the range 1.9072 (15)–1.9330 (15) Å and the N_imino—Ni—N_pyrrole bite angles are 83.18 (6)°. The Ni—N_pyrrole bond is substantially shorter than the Ni—N_imino bond. Molecules are linked into an extensive network by means of intermolecular C—H...π(arene) hydrogen bonds in which every molecule acts both as hydrogen‐bond donor and acceptor. The supramolecular assembly takes the form of an infinite two‐dimensional sheet.     

(R)‐N‐[(R)‐1‐(2‐Hydroxy‐5‐methyl­phenyl)‐2‐phenyl­ethyl]‐2‐methyl‐1‐phenyl­propyl­ammonium chloride

In the title compound, C₂₅H₃₀NO⁺·Cl⁻, the mol­ecules are linked by a combination of inter­molecular N—H⋯Cl and O—H⋯Cl hydrogen bonds and intra­molecular N—H⋯O hydrogen bonds. The absolute configuration of the new stereogenic centre (the C atom adjacent to the N atom on the phenol side) is determined to have an R configuration.     

Polymorph of {2‐[(2‐hydroxyethyl)iminiomethyl]phenolato‐κO}dioxido{2‐[(2‐oxidoethyl)iminomethyl]phenolato‐κ3O,N,O′}molybdenum(VI)

A second polymorphic form (form I) of the previously reported compound {2‐[(2‐hydroxyethyl)iminiomethyl]phenolato‐κO}dioxido{2‐[(2‐oxidoethyl)iminomethyl]phenolato‐κ³O,N,O′}molybdenum(VI) (form II), [Mo(C₉H₉NO₂)O₂(C₉H₁₁NO₂)], is presented. The title structure differs from the previously reported polymorph [Głowiak, Jerzykiewicz, Sobczak & Ziółkowski (2003). Inorg. Chim. Acta, 356 , 387–392] by the fact that the asymmetric unit contains three molecules linked by O—H...O hydrogen bonds. These trimeric units are further linked through O—H...O hydrogen bonds to form a chain parallel to the [11] direction. As in the previous polymorph, each molecule is built up from an MoO₂²⁺ cation surrounded by an O,N,O′‐tridentate ligand (O⁻C₆H₄CH=NCH₂CH₂O⁻) and weakly coordinated by a second zwitterionic ligand (O⁻C₆H₄CH=N⁺HC₂H₄OH). All complexes are chiral with the absolute configuration at Mo being C or A. The main difference between the two polymorphs results from the alternation of the chirality at Mo within the chain.     

(3R,4S)‐3‐Phenyl‐1‐[(R)‐1‐phenyl­ethyl]‐4‐[(R)‐1‐phenylethyliminomethyl]azetidin‐2‐one

The configuration of the chiral ring atoms of the title compound, C₂₆H₂₆N₂O, obtained in an enantioselective synthesis, has been established relative to the known R configuration of the α‐methyl­benzyl moieties. The crystal packing involves a two‐dimensional network of C—H?π interactions between the aromatic rings.