Two salts of 5‐sulfosalicylic acid and 3‐aminopyridine

5‐Sulfosalicylic acid (5‐SSA) and 3‐aminopyridine (3‐APy) crystallize in the same solvent system, resulting in two kinds of 1:1 proton‐transfer organic adduct, namely 3‐aminopyridinium 3‐carboxy‐4‐hydroxybenzenesulfonate monohydrate, C₅H₇N₂⁺·C₇H₅O₆S⁻·H₂O or 3‐APy·5‐SSA·H₂O, (I), and the anhydrous adduct, C₅H₇N₂⁺·C₇H₅O₆S⁻ or 3‐APy·5‐SSA, (II). Both compounds have extensively hydrogen‐bonded three‐dimensional layered polymer structures, with interlayer homo‐ and heterogeneous π–π interactions in (I) and (II), respectively.     

Di‐2‐pyridyl ketone 4‐methyl‐4‐phenyl­thio­semicarbazone

The mol­ecule of the title compound, C₁₉H₁₇N₅S, adopts a Z configuration about the azomethine bond and exists as the thione tautomer. The overall structure of the mol­ecule is distributed in four different planes. An intramolecular hydrogen bond involving the pyridyl N atom and the H atom attached to the hydrazine N atom leads to the formation of a six‐membered ring.     

From small structural modifications to adjustment of structurally dependent properties: 1‐methyl‐3,5‐bis[(E)‐2‐thienylidene]‐4‐piperidone and 3,5‐bis[(E)‐5‐bromo‐2‐thienylidene]‐1‐methyl‐4‐piperidone

The molecules of the title compounds, C₁₆H₁₅NOS₂, (I), and C₁₆H₁₃Br₂NOS₂, (II), are E,E‐isomers and consist of an extensive conjugated system, which determines their molecular geometries. Compound (I) crystallizes in the monoclinic space group P2₁/c. It has one thiophene ring disordered over two positions, with a minor component contribution of 0.100 (3). Compound (II) crystallizes in the noncentrosymmetric orthorhombic space group Pca2₁ with two independent molecules in the unit cell. These molecules are related by a noncrystallographic pseudo‐inversion center and possess very similar geometries. The crystal packings of (I) and (II) have a topologically common structural motif, viz. stacks along the b axis, in which the molecules are bound by weak C—H...O hydrogen bonds. The noncentrosymmetric packing of (II) is governed by attractive intermolecular Br...Br and Br...N interactions, which are also responsible for the very high density of (II) (1.861 Mg m⁻³).     

DFT study of the structure and spectral behavior of new pt(II) complexes with 5‐methyl‐5(4‐pyridyl)hydantoin

Platinum complexes are a great interest of study, because of the antitumor activity and the clinical use of some of them in the recent anticancer chemotherapy. In many cases, computational studies can be very useful for predicting the structure and some physicochemical properties of metal complexes. Theoretical calculations can also be used for the rational design of new complexes with optimal ratio: antitumor activity/toxicity. The geometry of three new Pt(II) complexes with general formula cis‐[PtL₂X₂] (where L is 5‐methyl‐5(4‐pyridyl)hydantoin and X = Cl^?, Br^?, I^?) and of the free organic ligand were optimized using the hybrid DFT method B3LYP with LAN2DZ basis sets. The results were in very good correlation with the data of similar compounds from the literature. The same DFT method was used for the study of their spectral behavior, by reproducing their IR and Raman spectra and comparing them with experimental data. In addition, the distribution of charges by ESP analysis was calculated. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2009     

1,4‐Bis[(1‐methyl‐1‐phenylethyl)peroxymethyl]benzene

The title compound, C₂₆H₃₀O₄, is one of the first alkyl bis‐peroxides to be structurally characterized. The mol­ecule lies on a centre of inversion and therefore the terminal phenyl rings are parallel. Although there are three aromatic rings in the mol­ecule, the C—O—O—C torsion angle of 163.10 (10)° is close to the value found in Me₃COOCMe₃.     

Three‐dimensional hydrogen‐bonding supramolecular architecture of 2‐(3‐pyridinio)‐5‐(3‐pyridyl)‐1,3,4‐oxa­diazole perchlorate

In the crystal structure of the title compound, C₁₂H₉N₄O⁺·ClO₄⁻, the protonated cation adopts a cis‐I conformation and approximately planar geometry. Each perchlorate anion acts as the acceptor of three C—H⋯O weak interactions, which, together with N—H⋯N and C—H⋯N hydrogen bonds between the protonated cations, extend this structure into a three‐dimensional hydrogen‐bonded network.     

Hydrogen‐bonded network in the trichloroacetate salts of 2‐amino‐5‐chloropyridinium and 2‐methyl‐5‐nitroanilinium monohydrate

In the crystal structures of 2‐amino‐5‐chloropyridinium trichloroacetate, C₅H₆ClN₂⁺·C₂Cl₃O₂⁻, (I), and 2‐methyl‐5‐nitroanilinium trichloroacetate monohydrate, C₇H₉N₂O₂⁺·C₂Cl₃O₂⁻·H₂O, (II), the protonated planar 2‐amino‐5‐chloropyridinium [in (I)] and 2‐methyl‐5‐nitroanilinium [in (II)] cations interact with the oppositely charged trichloroacetate anions to form hydrogen‐bonded one‐dimensional chains in (I) and, together with water molecules, a three‐dimensional network in (II). The crystals of (I) exhibit nonlinear optical properties. The second harmonic generation efficiency in relation to potassium dihydrogen phosphate is 0.77. This work demonstrates the usefulness of trichloroacetic acid in crystal engineering for obtaining new materials for nonlinear optics.     

Bis(5‐hydroxy‐2‐hydroxy­methyl‐4‐pyrone‐κ2O4,O5)bis(2‐hydroxy­methyl‐5‐oxido‐4‐pyrone‐κ2O4,O5)­calcium(II) tetrahydrate

In the title compound, [Ca(C₆H₅O₄)₂(C₆H₆O₄)₂]·4H₂O, which is a kojic acid–Ca²⁺ complex, the Ca atom is on a twofold axis and is octacoordinated by O atoms from four pyrone ligand mol­ecules. The hydroxyl and ketone O atoms of each ligand form a five‐membered chelate ring with the Ca atom. The crystal structure is stabilized by partial stacking and O—H?O hydrogen bonds.     

Synthesis and reactions of n‐methyl‐4‐(methylthio)thieno[2,3‐d]‐pyrimidinium salts

Two methods for the preparation of N‐methyl‐4‐(methylthio)thieno[2,3‐d]pyrimidinium salts 6a,b and 13a,b are described. Treatment of 6a,b and/or 13a,b with active methylene compounds such as malononitrile and ethyl cyanoacetate in the presence of sodium methoxide caused nucleophilic addition followed by elimination of methanethiol, giving the corresponding N‐methyl‐4‐ylidenethieno[2,3‐d]‐pyrimidines 7a,b, 8a,b, 14a,b and 15a,b .     

[2,6‐Bis(5‐methyl‐2‐pyridyl)phenyl‐κ3N,C1,N′]chloridoplatinum(II)

In the title compound, [Pt(C₁₈H₁₅N₂)Cl], the Pt^II centre adopts a distorted square‐planar coordination geometry due to the pincer‐type monoanionic N–C–N tridentate ligand. The planar complexes stack viaπ–π interactions to form two‐dimensional accumulated sheets. This packing pattern is in contrast to that in related pincer‐type N–C–N complexes, which exhibit a one‐dimensional columnar stacking.     

Crystallographic report: Bis[tris(2‐pyridyl)amine]cadmium(II)‐di‐µ‐chloro‐dichloro‐cadmium(II), [(C5H4N)3N]2CdCl2CdCl2

In the dinuclear molecule of [(C₅H₄N)₃N]₂CdCl₂CdCl₂, one cadmium is octahedrally coordinated by a Cl₂N₄ donor set and the other cadmium is tetrahedrally coordinated by four chlorine atoms. The dinuclear units are connected by π–π interactions to give a two‐dimensional network. Copyright © 2003 John Wiley & Sons, Ltd.     

Conformational polymorphs of 22‐cyano‐N‐methyl‐5‐phenylpent‐2‐en‐4‐ynamide

Although the two polymorphic modifications, (I) and (II), of the title compound, C₁₃H₁₀N₂O, crystallize in the same space group (P2₁/c), their asymmetric units have Z′ values of 1 and 2, respectively. These are conformational polymorphs, since the mol­ecules in phases (I) and (II) adopt different rotations of the phenyl ring with respect the central 2‐cyano­carboxy­amino­prop‐2‐enyl fragment. Calculations of crystal packing using Cerius² [Molecular Simulations (1999). 9685 Scranton Road, San Diego, CA 92121, USA] have shown that (I) is more stable than (II), by 1.3 kcal mol^?1 for the crystallographically determined structures and by 1.56 kcal mol^?1 for the optimized structures (1 kcal mol^?1 = 4.184 kJ mol^?1). This difference is mainly attributed to the different strengths of the hydrogen bonding in the two forms.     

Crystallographic report: Diiodo[tris(2‐pyridyl)amine]mercury(II), [(C5H4N)3N]HgI2

In mononuclear HgI₂[(C₅H₄N)₃N], mercury is tetrahedrally coordinated by two nitrogen atoms of a tris(2‐pyridyl)amine ligand and two iodides. The coordination moieties are connected by weak intermolecular Hg(II)···I interactions to give a one‐dimensional structure. Copyright © 2003 John Wiley & Sons, Ltd.     

Crystallographic report: Diiodo[tris(2‐pyridyl)amine]zinc(II), [(C5H4N)3N]ZnI2

The zinc(II) atom in the molecule of [(C₅H₄N)₃N]ZnI₂ is tetrahedrally coordinated to two nitrogen atoms of the tris(2‐pyridyl)amine ligand and two iodides. The coordination moieties are connected to give a linear structure by intermolecular π–π interactions between the pyridyl rings. Copyright © 2003 John Wiley & Sons, Ltd.     

2‐[2‐Methyl‐5‐nitro‐4‐(phenyl­sulfonyl­methyl)­imidazol‐1‐yl]­ethanol and 2‐methyl‐5‐nitro‐4‐phenyl­sulfonyl­methyl‐1,3‐thia­zole

The title compounds, C₁₃H₁₅N₃O₅S and C₁₁H₁₀N₂O₄S₂, respectively, both contain a phenyl­sulfonyl group connected, through a methyl­ene bridge, to either a substituted nitro­imidazole or nitro‐1,3‐thia­zole ring. In the imidazole‐containing mol­ecule, the nitro and sulfonyl groups are trans relative to the sulfonyl–methyl bond, while in the thia­zole‐containing mol­ecule, these substituents are cis. The stabilizing interactions within the crystals are also different between the two compounds.     

Green chemistry synthesis: 2‐amino‐3‐[(E)‐(2‐pyridyl)methylideneamino]but‐2‐enedinitrile monohydrate and 5‐cyano‐2‐(2‐pyridyl)‐1‐(2‐pyridylmethyl)‐1H‐imidazole‐4‐carboxamide

The title compounds, C₁₀H₉N₅O·H₂O (L1·H₂O) and C₁₆H₁₂N₆O (L2), were synthesized by solvent‐free aldol condensation at room temperature. L1, prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 1:1 molar ratio, crystallized as a monohydrate. L2 was prepared by grinding picolinaldehyde with 2,3‐diamino‐3‐isocyanoacrylonitrile in a 2:1 molar ratio. By varying the conditions of crystallization it was possible to obtain two polymorphs, viz. L2‐I and L2‐II; both crystallized in the monoclinic space group P2₁/c. They differ in the orientation of one pyridine ring with respect to the plane of the imidazole ring. In L2‐I, this ring is oriented towards and above the imidazole ring, while in L2‐II it is rotated away from and below the imidazole ring. In all three molecules, there is a short intramolecular N—H...N contact inherent to the planarity of the systems. In L1·H₂O, this involves an amino H atom and the C=N N atom, while in L2 it involves an amino H atom and an imidazole N atom. In the crystal structure of L1·H₂O, there are N—H...O and O—H...O intermolecular hydrogen bonds which link the molecules to form two‐dimensional networks which stack along [001]. These networks are further linked via intermolecular N—H...N(cyano) hydrogen bonds to form an extended three‐dimensional network. In the crystal structure of L2‐I, symmetry‐related molecules are linked via N—H...N hydrogen bonds, leading to the formation of dimers centred about inversion centres. These dimers are further linked via N—H...O hydrogen bonds involving the amide group, also centred about inversion centres, to form a one‐dimensional arrangement propagating in [100]. In the crystal structure of L2‐II, the presence of intermolecular N—H...O hydrogen bonds involving the amide group results in the formation of dimers centred about inversion centres. These are linked via N—H...N hydrogen bonds involving the second amide H atom and the cyano N atom, to form two‐dimensional networks in the bc plane. In L2‐I and L2‐II, C—H...π and π–π interactions are also present.     

Synthesis of alkyl 6‐methyl‐4‐(2‐pyridyl)‐1,2,3,4‐tetrahydro‐2H‐pyrimidine‐2‐one‐5‐carboxylates for evaluation as calcium channel antagonists

The Bigenelli acid catalyzed condensation of 2‐pyridylcarboxaldehyde ( 1 ), urea ( 2 ) and an alkyl acetoacetate ( 3 ) afforded the respective alkyl (Me, Et, i‐Pr, i‐Bu, t‐Bu) 6‐methyl‐4‐(2‐pyridyl)‐1,2,3,4‐tetrahydro‐2H‐pyrimidine‐2‐one‐5‐carboxylates ( 4a‐e ). The most potent calcium channel antagonist ethyl 6‐methyl‐4‐(2‐pyridyl)‐1,2,3,4‐tetrahydro‐2H‐pyrimidine‐2‐one‐5‐carboxylate ( 4b , IC₅₀ = 1.67 × 10^?5 M) wasa much weaker calcium channel antagonist than the reference drug nifedipine (Adalat®, IC₅₀ = 1.40 × 10^?8 M) on guinea pig ileal longitudinal smooth muscle (GPILSM). The alkyl 6‐methyl‐4‐(2‐pyridyl)‐1,2,3,4‐tetrahydro‐2H‐pyrimidine‐2‐one‐5‐carboxylates did not show any inotropic effect on heart since no increase, or decrease, in the contractile force of guinea pig left atrium was observed. These structure activity studies show that the alkyl 6‐methyl‐4‐(2‐pyridyl)‐1,2,3,4‐tetrahydro‐2H‐pyrimidine‐2‐one‐5‐carboxylates ( 4a‐e ) are partial bioisosteres of nifedipine with respect to calcium channel antagonist activity on guinea pig ileal longitudinal smooth muscle (GPILSM).     

Two hydration products of 3,4,5,6‐tetrachloro‐N‐(methyl‐2‐pyridyl)phthalmic acids

In 2‐amino‐6‐methylpyridin‐1‐ium 2‐carboxy‐3,4,5,6‐tetrachlorobenzoate, C₆H₉N₂⁺·C₈HCl₄O₄⁻, there are two perpendicular chains of hydrogen‐bonded ions, one arising from the interaction between 2‐carboxy‐3,4,5,6‐tetrachlorobenzoate ions and the other from the interaction between the 2‐amino‐6‐methylpyridin‐1‐ium and 2‐carboxy‐3,4,5,6‐tetrachlorobenzoate ions. These chains combine to form a two‐dimensional network of hydrogen‐bonded ions. Cocrystals of bis(2‐amino‐3‐methylpyridin‐1‐ium) 3,4,5,6‐tetrachlorophthalate–3,4,5,6‐tetrachlorophthalic acid (1/1), 2C₆H₉N₂⁺·C₈Cl₄O₄²⁻·C₈H₂Cl₄O₄, form finite aggregates of hydrogen‐bonded ions. π–π interactions are observed between 2‐amino‐3‐methylpyridin‐1‐ium cations. Both structures exhibit the characteristic R₂²(8) motif as a result of the hydrogen bonding between the 2‐aminopyridinium and carboxylate units.     

3‐[4‐(4‐Fluoro­phenyl)­piperazin‐1‐yl­methyl]‐5‐methyl‐1,3‐benzoxazol‐2(3H)‐one and 3‐[4‐(2‐fluoro­phenyl)­piperazin‐1‐yl­methyl]‐5‐methyl‐1,3‐benzoxazol‐2(3H)‐one

The title compounds, both C₁₉H₂₀FN₃O₂, contain essentially planar benzoxazolinone ring systems, within which the C—N bond distances and angles do not differ significantly between the two compounds. In both cases, the piperazine ring adopts an almost perfect chair conformation and the benzoxazo­l­inone ring system lies nearly perpendicular to it. The structures contain intermolecular C—H⋯O contacts, and the interactions between the benzoxazolinone and fluoro­phenyl­piperazine portions of the mol­ecules are segregated.     

2‐Amino‐5‐(2‐pyridyl)‐thiadiazole as Bidentate Ligand

The amino substituted bidentate chelating ligand 2‐amino‐5‐(2‐pyridyl)‐1,3,4‐thiadiazole (H₂ L ) was used to prepare 3:1‐type coordination compounds of iron(II), cobalt(II) and nickel(II). In the iron(II) perchlorate complex [Fe^II(H₂ L )₃](ClO₄)₂·0.6MeOH·0.9H₂O a 1:1 mixture of mer and fac isomers is present whereas [Fe^II(H₂ L )₃](BF₄)₂·MeOH·H₂O, [Co^II(H₂ L )₃](ClO₄)₂·2H₂O and [Ni^II(H₂ L )₃](ClO₄)₂·MeOH·H₂O feature merely mer derivatives. Moessbauer spectroscopy and variable temperature magnetic measurements revealed the [Fe^II(H₂ L )₃]²⁺ complex core to exist in the low‐spin state, whereas the [Co^II(H₂ L )₃]²⁺ complex core resides in its high‐spin state, even at very low temperatures.