O. Angelova

Crystalline complexes involving amino acids. II. (R)-(-)-1-phenylglycinium hydrogen squarate monohydrate

The title compound, C 8 H 10 NO 2 + .C 4 HO 4 - .H 2 O, crystallizes in the orthorhombic space group P2 1 2 1 2 1 in a layered structure of charged phenylglycinium and squarate/water layers stacked along the c axis and held together by an extensive hydrogen-bonding network. The amino group of the phenylglycine molecule adopts a proton from the squaric acid. The C-C bond lengths within the squarate anion are consistent with a delocalized double bond around the hydroxyl-bearing C atom: l.414(3) and l.431(3)A versus 1.481(3) and 1.494 (3) A for the opposite bonds in the ring.

Crystalline Complexes Involving Amino Acids. I. l-Argininium Hydrogen Squarate

The title compound, C 6 H 15 N 4 O 2 + .C 4 H O - 4 , crystallizes in the triclinic space group P1 with two independent formula units in the unit cell. The arginine molecules are protonated zwitterions with the amino and guanidyl moieties each accepting a proton from the acid group and the squaric acid. The torsion angles along the central N-C-(CH 2 ) 3 -N chains are -166.8(2), 165.7(2), 168.9(2), 178.2(2)° in molecule I and -170.0(1), 148.9(2), 164.1(2), 163.7(2)° in molecule II, respectively. The C-C bond lengths within the squarate anions are consistent with a delocalized double bond around the hydroxyl-bearing C atom, 1.426(3) and 1.433(3) A versus 1.496(3) and 1.491(3) A for the adjacent and opposite bonds, respectively. The crystal structure consists of alternate layers of squarate and argininium moieties stacked along the c axis. The adjacent layers are connected to each other through specific ion-pair interactions (salt bridges) between the guanidyl group of the argininium and the squarate moieties.

SYNTHESIS AND STRUCTURE OF Pd(II) COMPLEXES OF 1,2,3-TRIPHENYLGUANIDINE

Abstract The formation of two complexes by reaction of [PdCl4]2- with 1,2,3-triphenylguanidine (PhNH)2C=NPh under different metal/ligand ratios has been observed and the structure of the complex [(1,2,3-triphenylguanidine)2PdCl2] has been determined by X-ray diffraction methods. The ligands are coordinated as neutral monodentate molecules to the metal centre through their imine nitrogen atoms. The second Pd(II) complex is [Pd(1,2,3-triphenylguanidine)4]2+ and was isolated by precipitation with ClO− 4.

Synthesis of 11H-4b, 10b-dihydro [1] benzopyrano [4,3-c] isoquinoline-6,11 (5H)-diones and 13H-6c, 12b-dihydronaphtho [1′,2′:5,6]-pyrano [4-3c] isoquinoline-8,13 (7H)-dione from homophthalic anhydride and N-(2-hydroxyarylidene) alkylamines

Abstract 2-Alkyl-3-(2-hydroxyaryl)-3,4-dihydro-1(2H)-isoquinolinone-4-carboxylic acids (5,13) were prepared from homophthalic anhydride (1) and N-(2-hydroxyarylidene) alkylamines (2,10). The acids 5,13 showed a tendency towards cyclodehydration to give isoquinoline derivatives with fused [1] benzopyrane (8) or naphthopyrane (12) ring system. The relative configurations of the novel fused heterocyclic compounds 5,8,12,13 and related compounds were determined by NMR studies, and in the case of 13 also by means of X-ray analysis. Some MM2 force field molecular mechanics calculations on some selected fused heterocycles were executed. The naphtho [1′,2′:5,6] pyrano [4,3c]-isoquinoline ring system incorporated in the lactone 12 is hitherto unreported.

Preparation, Thermal Behaviour, and Structure of Calcium Trifluoroacetate Monohydrate

Summary. Calcium trifluoroacetate was prepared as its monohydrate Ca(CF3COO)2ċH2O by reaction of CaCO3 with an aqueous solution of CF3COOH. It has been established by thermogravimetry and differential thermal analysis that this salt possesses a low thermal stability. When heated in air, decomposition starts already at 106°C, yielding the final product CaF2. Single crystals of Ca(CF3COO)2ċH2O were obtained and found to be monoclinic (space group P21/n); unit cell parameters: a=9.465(2), b=9.360(3), c=16.565(7) Å.Zusammenfassung. Calciumtrifluoracetat wurde durch Reaktion von CaCO3 mit einer wäßrigen Lösung von CF3COOH als sein Monohydrat Ca(CF3COO)2ċH2O erhalten. Thermogravimetrische und differentialthermoanalytische Untersuchungen zeigen, daß dieses Salz eine geringe thermische Beständigkeit besitzt. Bei Erhitzen in Gegenwart von Luft beginnt die Zersetzung des Salzes bereits bei 106°C, wobei das Endprodukt CaF2 entsteht. Einkristalle von Ca(CF3COO)2ċH2O wurden hergestellt; sie sind monoklin (Raumgruppe P21/n). Parameter der Elementarzelle: a=9.465(2), b=9.360(3), c=16.565(7) Å.

Structures of threo(RR,SS) diethyl ester of 2-hydroxy-1,2-diphenylethylphosphonic acid and (±)diethyl ester of (1-hydroxycyclopentyl)(2-methylphenyl)methylphosphonic acid

The crystal structures of threo(RR,SS) diethyl ester of 2-hydroxy-1,2-diphenylethylphosphonic acid (1) and of (±)diethyl ester of (1-hydroxycyclopentyl)(2-methylphenyl)methylphosphonic acid (2) have been solved by X-ray methods. They are built up in a similar way to centrosymmetric dimers of hydrogen-bonded molecules. The orientation of the substituents around the central C-C bond in both molecules fulfills the requirement for the least spatial hindrance. The observed shift of theυoh stretching frequencies from 3312(1), 3346 (2) cm−1 in solid to 3408(1), 3450(2), in diluted (10−3M) tetrachloromethane solution, indicates the formation of intramolecular hydrogen-bonded species.

Magnesium Sulfate Tetraurea Monohydrate

In the title adduct, MgSO4.4CH2N2O.H2O {aqua(sulfato-O)tetrakis(urea-O)magnesium, [Mg(SO4)(CH4N2O)4(H2O)]}, the Mg atoms have octahedral coordination, formed by one water and four urea molecules, and one sulfate O atom. The neutral MgSO4(urea)4.H2O clusters are dimerized into centrosymmetric units through two O—H⋯O hydrogen bonds held together in a network where urea molecules act as both hydrogen-bond donors and acceptors.

Molecular Adducts of Inorganic Salts. VII. Cadmium Tetraoxorhenium Hexakis(thiourea) Hydrate

The title compound, [Cd(CH4N2S)6](ReO4)2..H2O, is built up of isolated centrosymmetric [Cd{SC(NH2)2}6]2+ octahedra, ReO4− tetrahedra and water molecules packed most densely in the ac plane. Two of the three nonequivalent thiourea molecules are almost parallel and the third one is perpendicular to the ac plane. The structural units are held together by a complex network of intra- and intercluster hydrogen bonds.

N -(2-Pyridyl)urea

The structure of the title compound, C6H7N3O, is built of layers stacked along the c axis and each layer consists of parallel zigzag ribbons of hydrogen-bonded molecules extended along the ab diagonals. Within the layers, the molecules are plane-to-plane coupled at 3.330 (2) A. The molecular planes from adjacent layers make an angle of 68.0 (1)°.

Hexakis(urea-O)magnesium dichlorate

In the title compound, [Mg{OC(NH2)2}6](ClO3)2, Mg atoms are octahedrally coordinated by the O atoms of six urea molecules. Urea1 is in-plane coordinated, while Urea2 and Urea3 are bonded with N21—C2—O2—Mg and N31—C3—O3—Mg torsion angles of 22.2 (4) and 27.3 (4)°, respectively. The structure is built up of [Mg(urea)6]2+ and ClO3− ions held together by hydrogen bonds.