Bartosz Zarychta

Synthesis, structural, and thermal characterization of a new binuclear copper(II) chelate complex bearing an amine-hardener for epoxy resins

Abstract A new di(μ-carbonato)bis[aqua(diethylenetriamine)copper(II)] hexahydrate complex, [{Cu(NH(C2H4NH2)2)(H2O)(μ-CO3)}2]·6H2O (1), was synthesized by direct interaction of malachite with diethylenetriamine (dien). The crystals of 1 were characterized by X-ray powder diffraction and IR spectra, as well as structurally characterized. Compound 1 consists of [{Cu(dien)(H2O)(μ-CO3)}2] discrete units whose anions play the role of bridging ligands combining two Cu(II) chelate cores into a centrosymmetric dimer. The elongated octahedral environment of Cu2+ consists of three nitrogens of dien and an oxygen from at the base of the bipyramid; the two apical positions of such polyhedron are occupied by an oxygen from an adjacent and an O from H2O. Combining the primary dimers into a framework is provided by O–H⋯O and N–H⋯O hydrogen bonds. The thermal behavior of 1 was investigated by differential thermal analysis. Thermal decomposition of 1 terminates at 400 °C, while the maximal combustion temperature of gaseous products is at 520 °C. Complex 1 may be an effective fire retardant and, at the same time, a curing agent for epoxy resins.

Acetyl­hydroxamic acid

There is one independent molxadecule in the asymmetric unit of the title compound (alternatively named N-hyxaddroxyxadacetamide), C2H5NO2. It crystallizes in the noncentrosymmetric space group P43. The structure is an anhydrous form of acetylxadhydroxamic acid with typical geometry that corresponds well with the hydrated structure described by Bracher & Small [Acta Cryst. (1970), B26, 1705–1709]. In the crystal, N—H⋯O and O—H⋯O hydrogen bonds connect the molxadecules into chains in the c-axis direction.

N-(Pyrazin-2-yl)adamantane-1-carboxamide

Molxadecules of the title compound, C15H19N3O, are composed of an adamantine unit and a pyrazine ring connected to each other through an amide bond. The H—N—C=O moiety is close to planar [C—N—C—O and C—N—C—C torsion angles of 4.7u2005(2) and −173.8u2005(1)°, respectively]. The N3—C5 bond has partial double-bond character [1.370u2005(1)u2005A]. The geometries of the pyrazine ring and the adamantane substituent are normal and in good agreement with closely related structures. In the crystal, molxadecules are connected by N—H⋯O hydrogen bonds, forming zigzag chains in the [001] direction and are arranged in a herringbone fashion.

Michael additions to double bonds of esters of N-protected (s)-phenylalanyldehydroalanine (X-(s)-Phe-ΔAla-OMe) and its phosphonic acid counterpart (X-(s)-Phe-ΔAla-PO(OEt)2)

GRAPHICAL ABSTRACT ABSTRACT Electrophilic addition of amines, thiols and bromide to the double bonds of model dehydrodipeptides and dehydrophosphonodipeptide was studied. The double bond in these two classes of peptides reacted similarly and gave the same products. These results indicate that dehydropeptides are very good candidates as substrates for modifications of peptide side-chains.

2-Methyl-N-(pyrazin-2-yl)propanamide–1,2,4,5-tetrafluoro-3,6-diiodobenzene (2/1)

In the title compound, C8H11N3O·0.5C6F4I2, molxadecules of iPr-substituted pyrazine are co-crystallized with 1,4-dixadiodo-2,3,5,6-tetraxadfluoroxadbenzene. The complete molecule of 1,4-diiodo-2,3,5,6-tetrafluorobenzene is generated by an inversion centre at the middle of the aromatic ring. Both molxadecules have normal geometry and the iPr acylxadamine group is disordered over two sets of sites with an occupancy ratio of 0.51:0.49. In the crystal, the components are linked by I⋯N halogen bonds [2.830u2005(2)u2005A] and C—H⋯F interxadactions are observed.