Ludmila S. Ivashkevich

Synthesis, characterization, and biological evaluation of new tetrazole-based platinum(II) and palladium(II) chlorido complexes--potent cisplatin analogues and their trans isomers.

Two series of tetrazole-containing platinum(II) and palladium(II) chlorido complexes, trans-[ML(2)Cl(2)] (M=Pt, Pd) and cis-[PtL(2)Cl(2)]·nH(2)O (n=0, 1), where L is 1- or 2-substituted 5-aminotetrazole, have been synthesized and thoroughly characterized. Configuration of platinum(II) complexes obtained from the reaction of 5-aminotetrazoles with K(2)PtCl(4) has been found to vary depending on the nature of tetrazole derivatives and reaction conditions. According to in vitro cytotoxic evaluation, only platinum complexes display noticeable antiproliferative effect, and their cytotoxicity depends strongly on their geometry and hydrophobicity of the carrier ligands. The most promising complexes are cis-[Pt(1-apt)(2)Cl(2)]·H(2)O and cis-[Pt(2-abt)(2)Cl(2)]·H(2)O, where 1-apt is 5-amino-1-phenyltetrazole and 2-abt is 5-amino-2-tert-butyltetrazole. In comparison with cisplatin, they show comparable cytotoxic potency against cisplatin-sensitive human cancer cell lines, cis-[Pt(2-abt)(2)Cl(2)]·H(2)O performing substantially higher activity against cisplatin-resistant cell lines. Cell cycle studies in H1299 cell line indicated that cis-[Pt(2-abt)(2)Cl(2)]·H(2)O induced apoptosis launched from G2 accumulations. The DNA interaction with cis-[Pt(1-apt)(2)Cl(2)]·H(2)O was followed by UV spectroscopy, circular dichroism, hydrodynamic and electrophoretic mobility studies. Both cis-[Pt(1-apt)(2)Cl(2)]·H(2)O and cis-[Pt(2-abt)(2)Cl(2)]·H(2)O complexes appeared to be significantly less toxic than cisplatin in mice, while only compound cis-[Pt(1-apt)(2)Cl(2)]·H(2)O displayed noticeable efficacy in vivo.

Two derivatives of 5-aminotetrazole: 5-amino-1-phenyltetrazole and 5-amino-1-(1-naphthyl)tetrazole

In the molecules of 5-amino-1-phenyltetrazole, C(7)H(7)N(5), (I), and 5-amino-1-(1-naphthyl)tetrazole, C(11)H(9)N(5), (II), the tetrazole rings and aryl fragments are not coplanar; corresponding dihedral angles are 50.58 (5) and 45.19 (7) degrees for the two independent molecules of (I), and 64.14 (5) degrees for (II). Intermolecular N-H.N hydrogen bonds between the amino groups and tetrazole N atoms are primarily responsible for formation of two-dimensional networks extending parallel to the bc plane in both compounds. The presence of the amino group has a distinct effect on the geometry of the tetrazole rings in each case.

Two isostructural manganese (III) diphosphates, acid α-MnHP2O7 and double MnLiP2O7: crystal structure determination from X-ray powder diffraction data

Summary Ab initio crystal structure determination of the α form of MnHP2O7 and Rietveld refinement of the MnLiP2O7 structure were performed using powder X-ray diffraction data. The final structures have been obtained using soft restraints on interatomic bond lengths and bond angles for the diphosphate group. The two compounds were found to be to a great extent isostructural. They crystallize in the monoclinic space group P21, Z = 2, a = 6.7547(6), b = 8.3160(7), c = 4.8769(5) Å, β = 113.1791(18)°, Rp = 0.0283, Rwp = 0.0390, RBragg = 0.0930, RF = 0.0869 for α-MnHP 22O7, and a = 7.0018(5), b = 8.1616(6), c = 4.7267(4)Å, β = 109.404(3)°, Rp = 0.0307, Rwp = 0.0423, RBragg = 0.0960, RF = 0.0861 for MnLiP2O7. In both compounds, diphosphate groups adopt nearly eclipsed configuration. Their structures present three-dimensional networks, which have tunnels including the lithium cations or hydrogen atoms. The behaviour of the crystalline forms of MnHP2O7 in H/Li exchange reactions is discussed, vs. their structural aspects.

Two succinic acid derivatives of 2-ethyl-6-methylpyridin-3-ol.

Crystals of bis(2-ethyl-3-hydroxy-6-methylpyridinium) succinate-succinic acid (1/1), C(8)H(12)NO(+)·0.5C(4)H(4)O(4)(2-)·0.5C(4)H(6)O(4), (I), and 2-ethyl-3-hydroxy-6-methylpyridinium hydrogen succinate, C(8)H(12)NO(+)·C(4)H(5)O(4)(-), (II), were obtained by reaction of 2-ethyl-6-methylpyridin-3-ol with succinic acid. The succinate anion and succinic acid molecule in (I) are located about centres of inversion. Intermolecular O-H···O, N-H···O and C-H···O hydrogen bonds are responsible for the formation of a three-dimensional network in the crystal structure of (I) and a two-dimensional network in the crystal structure of (II). Both structures are additionally stabilized by π-π interactions between symmetry-related pyridine rings, forming a rod-like cationic arrangement for (I) and cationic dimers for (II).

Copper(II) chloride and bromide complexes with 2-methyl-2H-tetrazol-5-amine: an X-ray powder diffraction study.

The complex catena-poly[[dibromidocopper(II)]-bis(mu-2-methyl-2H-tetrazol-5-amine)-kappa(2)N(4):N(5);kappa(2)N(5):N(4)], [CuBr(2)(C(2)H(5)N(5))(2)](n), (I), and the isotypic chloride complex catena-poly[[dichloridocopper(II)]-bis(mu-2-methyl-2H-tetrazol-5-amine)-kappa(2)N(4):N(5);kappa(2)N(5):N(4)], [CuCl(2)(C(2)H(5)N(5))(2)](n), (II), were investigated by X-ray powder diffraction at room temperature. The crystal structure of (I) was solved by direct methods, while the Rietveld refinement of (II) started from the atomic coordinates of (I). In both structures, the Cu atoms lie on inversion centres, adopting a distorted octahedral coordination of two halogen atoms, two tetrazole N atoms and two 5-amine group N atoms. Rather long Cu-N(amine) bonds allow consideration of the amine group as semi-coordinated. The compounds are one-dimensional coordination polymers, formed as a result of 2-methyl-2H-tetrazol-5-amine ligands bridging via a tetrazole N atom and the amine N atom. In the polymeric chains, adjacent Cu atoms are connected by two such bridges.

Neutron and synchrotron X-ray powder study of copper(II) chloride complex with deuterated 1-ethyltetrazole

Abstract The structure of the copper(II) chloride complex with deuterated 1-ethyltetrazole has been investigated in the temperature range of 2–290 K using neutron and synchrotron X-ray powder diffraction. The compound was found to exhibit structural transformation at ca. 180 K, without change of space group and main structural motif. At higher temperatures, the complex reveals positional disorder of the ethyl group, whereas no disorder is observed at lower temperatures. Temperature dependence of the lattice parameters, obtained from synchrotron X-ray data, showed main lattice changes at the transformation, explained by structural features of the complex. From the magnetic measurements, the effect of the disorder on paramagnetic behaviour of the compound was found. Detailed structural data of the compound at 2 and 290 K, obtained from neutron powder diffraction data, are reported.

catena-Poly[[bis­[1-(2-hydroxy­ethyl)-1H-tetra­zole-κN4]copper(II)]-di-μ-chlorido]: a powder study

The crystal structure of the title polymeric complex, [CuCl2(C3H6N4O)2]n, was obtained by the Rietveld refinement from laboratory X-ray powder diffraction data collected at room temperature. The unique CuII ion lies on an inversion center and is in a slightly distorted octahedral coordination environment. In the hydroxyethyl group, all H atoms, the O atom and its attached C atom are disordered over two positions; the site occupancy factors are ca 0.6 and 0.4. The OH group is involved in an intramolecular O—H⋯N hydrogen bond.

Coordination polymers formed by bridging 2‐substituted tetra­zole ligands: poly[[dichloro­copper(II)]‐di‐μ2‐2‐prop­yl‐2H‐tetra­zole‐κ2N1:N4] and poly[[dichloro­copper(II)]‐di‐μ2‐2‐all­yl‐2H‐tetra­zole‐κ2N1:N4]

Two polymeric complexes, [CuCl2L2]n, where L is 2-propyltetrazole (C4H8N4) or 2-allyltetrazole (C4H6N4), are the first coordination polymers of 2-substituted tetrazoles in which only the tetrazole rings bridge neighbouring Cu atoms. In both complexes, the Cu atoms lie on inversion centres and are six-coordinated in tetragonally distorted octahedral geometries, CuCl2N4, with two N1 tetrazole ring atoms in the axial positions and two Cl atoms and two N4 tetrazole ring atoms in the equatorial sites. The Cl atoms do not participate in the polymeric layer formation.

Zwitterionic 5-(1-piperidiniomethyl)-1H-tetrazolide

The title compound, C(7)H(13)N(5), a tetrazole analogue of betaines, exists as a zwitterion, with the H atom of the tetrazole ring being transferred to the piperidine ring N atom. The tetrazole ring symmetry is close to C(2v), which suggests strong charge delocalization in the N-C-N fragment of the ring. There are classical hydrogen bonds in the structure which are responsible for the formation of two-membered aggregates.

The crystal structure of Y2P4O13 from X-ray powder diffraction data

Abstract The crystal structure of Y2P4O13 has been determined from X-ray powder diffraction data. Y2P4O13 crystallizes in the orthorhombic space group C2221 (No. 20) with a = 17.2817(7) Å, b = 6.9823(4) Å, c = 8.5391(3) Å, V = 1030.38(8) Å3, and Z = 4. The structure has been solved by direct methods using EXPO program and refined by FULLPROF package. The final RBragg value was 9.1%. The tetraphosphate anion has the point group 2 symmetry. The yttrium atom is seven-coordinated forming strongly distorted octahedron with one bifurcated vertex. There are infinite chains of oxygen-bridged ittrium atoms running parallel to the b axis and linked together by the tetraphosphate anions with formation of three-dimensional network.