Rosica Petrova

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.

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.

Structure, conformation and hydrogen bonding of two amino-cycloalkanespiro-5-hydantoins

The crystal structures of 3-amino-cycloheptanespiro-4′-imidazolidine-2′,5′-dione (I) {systematic name: 3-amino-1,3-diazaspiro[4.6] undecane-2,4-dione} and 3-amino-cyclooctanespiro-4′-imidazolidine-2′,5′-dione (II) {systematic name: 3-amino-1,3-diazaspiro[4.7] dodecane-2,4-dione}, have been determined. In both compounds the polar hydantoin groups cause molecules to aggregate via N-H...O and N-H...N interactions, forming a layer structure, in which the cycloalkane rings project outwards from the central, more polar, region. The observed molecular structure is compared with that calculated by density functional theory methods.

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.

Synthesis and crystal structure of a Pt(II) complex with 3-amino-5-methyl-5-phenylhydantoin

The reaction of K2PtCl4 with 3-amino-5-methyl-5-phenylhydantoin (amphh, L) and KI in aqueous ethanol yields dark violet crystals of a binuclear platinum(II) complex. The molecular structure of the complex was determined by single-crystal X-ray diffraction methods. The complex crystallizes in the triclinic space group with a = 8.458(3), b = 11.016(2), c = 16.249(3) (Å), α = 94.630(14), β = 100.63(2), γ = 108.55(4)° and Z = 2. The structure consists of [K2L4]2+ cations and [Pt2I6]2− anions bridged by K–I bonds to form quasi-one-dimensional chains along the b axis. Chains are linked by K+ ··· π(Ph) interactions and N–H ··· O hydrogen bonds. The complex is compared with data for related structures.

2-(3-benzoyl-1-pyridinio)-3,4-dioxocyclobutenolate.

The title compound, C16H9NO4, also known as the 3-benzoylpyridinium betaine of squaric acid, exhibits a dipolar electronic ground-state structure with a positively charged pyridinium fragment and a negatively charged squarate moiety. In the molecule, the two aromatic rings are twisted by 56.03 (2) degrees relative to one another. The three-dimensional packing of the molecules is stabilized by C-H...O short contacts.

[(4,4-Dimethyl-2-oxo-1,3-oxazolidin-3-yl)methyl]phosphonic acid.

The title compound, C6H12NO5P, was synthesized as an intermediate phase in a search for new N-(phosphonomethyl)glycine derivatives. The molecules are held together by O-H...O hydrogen bonds, forming chains along the b axis in the crystal structure. The observed molecular structure is compared with that calculated by the density functional theory method.

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.

Molecular Adducts of Inorganic Salts. VI. The Dimorphism of Cd(ReO4)2.2tu (tu = Thiourea)

The title compound, cadmium tetraoxorhenium bis(thiourea), Cd(ReO4)2.2CH4N2S, forms two polymorphs: monoclinic, (I), and triclinic, (II). Both are built up of infinite chains in which the Cd atoms are hexacoordinate. In (I), the centrosymmetric CdO4S2 octahedra are interlinked by double ReO4 bridges, while in (II), CdO3S3 octahedra are connected by alternating double ReO4 and S bridges. The Cd—S coordination bond length is 2.495 (2) A in (I) and ranges from 2.576 (2) to 2.719 (2) A in (II). The hydrogen bonding between chains is more developed in compound (II).