Ruth C. Palenik

A ten-coordinate lead complex with an unusual 2-6-2 coordination polyhedron

Etude structurale du complexe Pb(PHENSC) (NO 3 ) 2 avec PHENSC=diformyl-2,9 phenanthroline-1,10 disemicarbazone

Reactions of seven coordinate complexes. Synthesis, structure, and copper complex of the novel ligand 3-methyltriazolo(1,5-a)6-acetylsemicarbazonepyridine

Abstract The reaction of aquachloro(2,6-diacetylpyridinedisemicarbazone)copper(II) with hydrazine hydrate gave the copper complex of 3-methyltriazolo(1,5-a)6-acetylsemicarbazonepyridine. The free ligand was isolated from the copper complex. The X-ray structures of both the copper complex and the free ligand are reported. The copper complex and the free ligand both crystallize in the triclinic space group P 1 with 2 molecules per cell. The Cu complex has cell dimensions of a=8.8574(4), b=10.1764(5), c=10.4434(5) A, α=71.956(1), β=64.913(1), and γ=81.597(1)°. The Cu ion is in a square pyramidal arrangement, with the Cu, the ligand, and a Cl in the plane and a disordered Cl and H2O in the apical position. The ligand has cell dimensions of a=7.2696(7), b=8.0516(7), c=9.9326(9) A, α=110.534(2), β=96.730(2), and γ=100.089(2)°. The ligand is planar with a conformation determined by an internal N–H⋯H hydrogen bond. The role of the Cu ion in the formation of the triazolopyridine is discussed.

2-[1-(Salicyloylhydrazono)ethyl]pyridinium Chloride Dihydrate at 173K

The approximately planar molecule of the title compound, C 14 H 14 N 3 O 2 + .Cl - .2H 2 O, is in an E conformation with respect to the C=N bond, with a C-C=N-N torsion angle of 179.5(1)°. The maximum possible number of hydrogen bonds are formed in the crystal. The pyridinium H atom forms a hydrogen bond to a water molecule which is hydrogen bonded to the carbonyl O atom, requiring the pyridine ring to be rotated 180° compared to the unprotonated 2-formylpyridine analog. There is an intramolecular hydrogen bond involving the NH group on the chain and the hydroxyl O atom on the phenyl ring which, in turn, is hydrogen bonded to a Cl - ion. Finally, a water molecule and chloride ion form a hydrogen-bonded square around a center of symmetry, with O...Cl distances of 3.199(2) and 3.206 (2) A, and endocyclic angles of 91.17 (4) and 88.83 (4)° at the O and Cl atoms, respectively.

Tetraaqua[2,6-diacetylpyridinedi(acetic acid hydrazone)]yttrium(III) nitrate trihydrate. Synthesis, crystal structure and 89Y, 13C, 1H NMR

The synthesis, crystal structure, and 89Y, 13C, and 1H NMR spectra of tetraaqua[2,6-diacetylpyridinedi(acetic acid hydrazone)]yttrium(III) nitrate trihydrate, [Y(H2dapaah)(H2O4)4]3+ 3NO−3·3H2O (1). the first reported complex of YIII with a planar pentadentate ligand is presented. The YIII ion coordinates to the pyridyl nitrogen, the two hydrazone nitrogens, and the two carbonyl oxygens of the pentadentate ligannd and three water molecules above and one below the ligand plane to give a nine-coordinated complex. The geometry around the YIII is a slightly distorted tricapped trigonal prism. The 89Y chemical shift was determined to provide additional data on the relationship of the chemical shift to the coordination polyhedron for Y complexes since 89Y NMR has been suggested as a probe for biological systems. The 89Y spectrum shows a peak at + 1.53 ppm from the YCl3 standard, one of the smallest chemical shifts relative to the standard reported to date and is the first example where the YIII is coordinated to a neutral ligand.

Aqua[2,6-diacetylpyridinedi(benzoic acid hydrazone)]nitratocobalt(II) Nitrate at 173K

The structure of aqua(nitrato-O){pyridine-2,6-diylbis-[N-(1 -ethylideneamino)benzamide]-O 1 ,N 2 ,N 1 ,N 5 ,O 2 }-cobalt(II) nitrate, [Co(NO 3 )(C 23 H 21 N 5 O 2 )(H 2 O)]NO 3 , was redetermined at 173 K. There are only small differences between the bond distances in the cation at 173 K relative to the room-temperature determination reported previously. The average difference is 0.006 A for all 45 bond distances and only 0.004 A for 27 bonds if the two phenyl rings and two nitrate ions, which have large thermal motions, are excluded. The Co atom is in the center of a pentagonal bipyramid consisting of the pentadentate ligand, with a water molecule and monodentate nitrate ligand in the axial positions.

Structural studies of two tetracyclines: 4-dedimethylaminotetracycline hydrate and 6-methylene-5-oxytetracycline hydrochloride

The crystal structures of two tetracycline derivatives, 4-dedimethylaminotetracycline hydrate and 6-methylene-5-oxytetracycline hydrochloride (methacycline·HCl), were determined using X-ray intensity data measured on a diffractometer. The first compound crystallizes with two chemical formula and one water molecule per asymmetric unit. The monoclinic crystal [a=7.174(5),b=12.029(9),c=21.117(15) Å,β=93.16(6)°] shows the space groupP21. Crystals of methacycline hydrochloride are orthorhombic, space groupP212121,a=9.472(1),b=11.921(3),c=18.945(4)Å, with one molecule in the asymmetric unit.

Synthesis and structure of μ-3,3′-[ 1,2-ethanediyl-bis(nitrilomethylidyne)-bis(2-hydroxybenzoato)] aquadicopper(II) hydrate

Abstract The complex μ-3,3′-[1,2-ethanediyl-bis(nitrilome- thylidyne)-bis(2-hydroxybenzoato)] aquadicopper(II) hydrate, C18H16N2O8Cu2, was isolated from an attempted preparation of a copper lanthanum binuclear complex. The dark purple crystals are monoclinic, space group P21/n, with 4 molecules per unit cell; dimensions a = 13.961(5), b = tl.787(3), c = 11.622(3) A and β = 113.09(2)°. The final R was 0.046 for the 2062 reflections used in the analysis. The Cu atom in the N2O2 cavity is five coordinate with CuN distances of 1.879 and 1.880 A and CuO distances of 1.898 and 1.900 A. A water molecule at 2.557 A completes the square pyramidal arrangement. The second Cu in the O4 cavity is square planar, with CuO distances to the bridging oxygens of 1.914 and 1.909 A and to the carboxy oxygens of 1.871 and 1.882 A. A survey of copper complexes in a square planar N2O2 arrangement has led to the equation δCu from the N2O2 plane = 0.822 – 0.275 (CuO axial distance) with a correlation coefficient of 0.98 for the 12 structures in which the Cu atom is bonded to a fifth oxygen atom. A model for the transition from square planar to square pyramidal geometry is proposed.

An unusual copper promoted hydroxylation

The addition of a second mole of copper chloride to the reaction of copper chloride with diacetylpyridine and semicarbazide hydrochloride gives an unusual hydroxylated product.

Nonbonded interactions. A thiophene S ⋯ N intramolecular attraction. Crystal structure of 2-formylthiophene semicarbazone

Thiophene derivatives can exhibit a novel intramolecular nonbonded S ⋯ N attraction which is observed in 2-formylthiophene semicarbazone, as well as other derivatives.

Synthesis and X-ray characterization of the novel pentagonal bipyramidal chromium complex, diaqua-(2,6-diacetylpyridine bis-semicarbazone)- chromium(III) hydroxide dinitrate monohydrate

The first pentagonal bipyramidal chromium(III) complex has been prepared and characterized, suggesting that seven-co-ordination may not be as rare as previously assumed and may also be the geometry of intermediates in octahedral substitution reactions.