Jon Bordner

2-Tridecanone: A Naturally Occurring Insecticide from the Wild Tomato Lycopersicon hirsutum f.glabratum

A nonalkaloid insecticide was isolated from the wild tomato Lycopersicon hirsutum f. glabratum and identified as 2-tridecanone, a compound 72 times more abundant in the wild tomato than in the cultivated tomato L. esculentum. Lepidopterous larvae (Manduca sexta and Heliothis zea) and aphids (Aphis gossypii) died when confined on 2-tridecanone-treated filter paper.

Effect of day length and light intensity on 2-tridecanone levels and resistance inLycopersicon hirsutum f.glabratum toManduca sexta

First instarManduca sexta (L.) larvae confined on foliage fromLycopersicon hirsutum f.glabratum (accession PI 134417) plants grown under a long-day regime exhibited greater mortality than larvae on foliage from plants grown under a short-day regime. 2-Tridecanone, a toxin important in the insect resistance of PI 134417, was significantly more abundant in the foliage of plants grown under the long-than the short-day regimes. Light intensity influenced neither 2-tridecanone levels nor the expression of resistance. The density of glandular trichomes, which secrete 2-tridecanone, was influenced by an interaction between day length and light intensity.

Crystal and molecular structure of [N, N′-ethylenebis(methyl-2-amino-1-cyclopentenedithiocarboxylato)]copper(II): A quantitative relationship between tetrahedral distortion and redox potentials in copper N2S2 compounds and the relevance to type I copper(II) centers ☆

The crystal and molecular structure of the copper(II) complex of the N2S2 tetradentate ligand, ethylenebis(methyl-2-amino-1-cyclopentenedithiocarboxylate), was solved at room temperature by a single crystal x-ray diffraction study. The complex crystallizes in the orthorhombic space group P212121 with a = 7.739(1) A, b = 13.893(2) A, c = 17.096(3) A, V = 1838(1) A3, ϱobserved = 1.56 g cm−3 and ϱcalculated = 1.57 g cm−3 for a molecular weight of 434.2, and Z = 4. Diffraction data were collected with a Syntex P diffractometer using graphite-monochromatized Cu (λ = 1.5418 A) radiation. The heavy atoms were located from a Patterson synthesis; all other nonhydrogen atoms were located using difference Fourier techniques, and hydrogen atoms were placed in calculated positions. Final refinement resulted in discrepancy indices of R = 0.067 and goodness of fit of 2.92 for all 995 reflections (5° < 2θ < 100°) greater than three times their standard deviation. The molecules are monomeric and well separated. Bond distances in the two ”halvesldquo; of the ligand are sufficiently different to suggest that different resonance structures exist in each portion. This agrees with the rhombic symmetry displayed by the frozen glass esr spectrum of the compound (xx ≠ gyy). The dihedral angle between the planes defined by the CuN2 and CuS2 planes is 20.0°, indicating a rather distorted inner coordination sphere. The copper(II)-copper(I) reduction potentials found for this compound and the trimethylene and tetramethylene analogs were determined to be −1.01, −0.79, and −0.64 V respectively. A quantitative relationship between tetrahedral distortion and redox potentials is obtained, and these results are discussed in terms of ”blueldquo; copper(II) sites in proteins. Trends in CuS and CuN bonding patterns in the same three compounds are discussed with regard to the short CuS (cys) bond distance in plastocyani Finally, a brief discussion of the optical spectra of these three compounds, their variation, and their significance with respect to tetrahedral symmetry in copper(II) protein sites is presented.

The crystal and molecular structure of diiodotetrakis(pyridine)nickel(II) [Nipy4I2]

Abstract The crystal structure of diiodotetrakis(pyridine)nickel (II), [Nipy 4 I 2 ] has been determined accurately by three-dimensional, single-crystal X-ray analysis. The orthorhombic cell of space group Pbcn has a = 9.678(4) A, b = 16.077(6) A, and c = 14.004(4) A, with four molecules per unit cell (density = 1.88 g/cm 3 experimental, and 1.92 g/cm 3 calculated). The structural refinement was terminated at R = 0.042. The molecule was found to have the geometric trans configuration, and this supports electronic spectroscopic conclusions. The nickel atom is surrounded by the four nitrogen atoms of pyridine molecules so that the group (NiN 4 ) defines a plane. The four nitrogen atoms deviate but slightly from defininig a square. The INiI moiety is nearly linear so that any one NiI) vector deviates only slightly (∼2) from being perpendicular to the (NiN 4 ) plane. The average NiN distance in [Nipy 4 I 2 ] is the largest (2.127(7) A) such bond length yet observed for high-spin Ni II -pyridine complexes. Regarding the pyridine ring, the average CC bond distances of coordinated pyridine are found to be shorter than those of the free pyridine molecule. It is also interesting that the two planes of each pair of trans pyridine molecules are found to be staggered (∼90°) whereas both eclipsed and staggered configurations were previously reported for other, but somewhat related molecules. Each of the four pyridine molecules has a pitch angle of ca. 45° with respect to the near-C 4 axis along NiI. The pyridine molecules also define a four-blade propeller, since this “C 4 ” axis brings one pyridine molecule nearly into coincidence with the others. The structural relationships of [Nipy 4 I 2 ] are also compared with those of other metal-pyridine complexes.

Sirodesmin A: Synthesis of a chiral left half.

Abstract A stereoselective and chiral synthesis of a precursor to the fungal metabolite sirodesin A ( 1 ) is described. The correct relative and absolute confirugation for intermediate 3 (Scheme 1) is established in a single, highly enantioselective epoxidation.

Resonance induced properties in monothiocarbamates derived from aromatic amines: comparison of the coordination chemistry of indole and indoline monothiocarbamates ☆

Abstract The syntheses of two new monothiocarbamate ligands and selected transition element complexes of each are reported. The complexes of indoline-N-carbothioate (intc) prepared are: NiL2·1.5H2O, ZnL2, NiL2·2py, ZnL2·2py. The complexes of indole N-carbothioate (iltc) are: NiL′2, ZnL′2, Cul′. IR spectral results support a bidentate ligand behavior for both new monothiocarbamates except in ZnL2·2py. Comparison of the IR spectral features of bis(indolylcarbamoyl)-disulfide with that of coordinated indole-N-carbothioate allowed an assignment of the C-S and C-O vibrational frequencies. Evidence for differences in major resonance contributions to the electronic structures of each new ligand are presented. The crystal structure of the bis(indolylcarbamoyl)disulphide is also presented and a comparison is made to pyrrole-N-carbothioate, another aromatic amine monothiocarbamate. The disulphide crystallizes in the centrosymmetric monoclinic space group P21/c with a = 15.64(4)A, b = 5.228(1)A, c = 19.271(7)A, β = 97.20(2)°, V = 1564(1)A3, d(obsd)(calcd) = (1.50)(1.52) for a molecular weight = 356.1 and Z = 4. Diffraction data were collected with a Syntex P 1 - diffractiometer with CuKα radiation. Least squares refinement resulted in Rf = 7.0% for all 1213 non zero reflections have (I)> 3σ(I).

Stereoelectronic properties of metalloenzymes. 10. a refined model that mimics the type II copper(II) site in galactose oxidase

A number of copper(II) complexes of tridentate ligands with various donor atoms have been studied in an attempt to duplicate the unusual reactivity patterns and accompanying spectral changes of the copper(II) center in galactose oxidase. Results indicate that in order to match the optical and electron spin resonance spectral change observed upon CN− binding by the enzyme, an equatorial, negative ligand must be displaced in a small molecule model. The crystal and molecular structure of the best model complex was solved by a single crystal X-ray diffraction study. The compound, monoacetato-1,3-bis(2-(4-methyl-pyridyl)imino)isoindolatocopper(II), crystallizes in the centro-symmetric triclinic space group PĪ with a = 7.392(3) A, b = 13.782(5) A, c = 23.422(12) A, α = 92.08(3)°, β = 104.11(5)°, γ = 109.98(4)°, V = 2156(1) A3, d(obsd.)(calc.)=(1.43)(1.44) g/cm−3 for mol wt of 466.7 and Z = 4. Diffraction data were collected with a Syntex Pl diffractometer using graphite-monochromatized Cu radiation (λ = 1.5418 A). The copper atoms were located from a Patterson synthesis; all other nonhydrogen atoms were located via difference. Fourier techniques, and hydrogen atoms were placed in calculated positions. Final refinement resulted in discrepancy indices of R = 0.089 and “Goodness to Fit” = 3.68 for all 3608 reflections having (I) ⩾ 3σ(I) (5°<2θ<100°). There are two unique molecules in the asymmetric unit that are monomeric and well separated. The geometry around the copper atom is approximately square pyramidal, with the coordination sphere derived from three nitrogens of the tridentate ligand, one oxygen from the acetate unit, and an oxygen atom of a water molecule occupying an axial position. The structure is surprising both in that an axial water molecule is present and that the remaining four ligand atoms to the copper atom are rather distorted from a planar configuration. The plane defined by the copper, N5, and N3 atoms intersects the plane defined by the copper, Nl, and Ol, atoms forming a “twist angle” of 25.0° (0.0° would be ideal for a planar inner coordination sphere). The stereoelectronics of the inner coordination spheres of the type II Cu(II) enzymes galactose oxidase and superoxide dismutase are discussed and appropriate comparisons are made with emphasis on the origin of spectral changes observed upon anion binding.

The structure of d-threo-2,5-hexodiulosonic acid and derivatives in solution

Abstract The structure of d -threo-2,5-hexodiulosonic acid (1) and various derivatives in solution was determined by 13C-n.m.r. spectroscopy to be a hydrated, pyranose form. The structures of the methyl ester of 1 and of its 5-(dimethyl acetal) were confirmed by chemical means and by X-ray structure analysis.

Cuticular wax of Epilachna varivestis

Abstract Cuticular lipids of larvae, pupae and adults of the Mexican bean beetle (Epilachna varivestis) have been examined using gravimetric and thin layer densitometric techniques. The effects of rearing on different hostplants and of rearing temperature on lipid composition were studied. Total lipid varied with developmental stage as well as hosplant. The amount of lipid extracted ranged from 3.0 mg/g wet weight, in the case of larvae reared on snapbeans in the field, to 5.2 mg/g wet weight for pupae reared in limas under field conditions. Total lipid increased with increasing temperature for larvae reared under controlled climatic conditions. Thin layer densitometry was used to quantify lipid classes. Epicuticular lipids included hydrocarbons, wax esters, triacylglycerols, fatty alcohols, free fatty acids, sterols, three unidentified materials and alkaloid(s). Lipids of larval and pupal stages were composed primarily of wax esters, hydrocarbons and fatty alcohols in roughly equal proportions; free fatty acids, triacylglycerols, sterols, alkaloid(s) and two unknown materials made up of the remainder. Adult cuticular lipids consisted mainly of hydrocarbons (49–60% of total lipid).

Molecular and crystal structures of halopentaamminerhodium-(III) complexes, [Rh(NH3)5Cl]Cl2 and [Rh(NH3)5Br]Br2

The crystal and molecular structures of the title compounds have been determined by three-dimensional single-crystal X-ray techniques. All crystallographic details are fully reported. The major chemical conclusion for the pair, [Rh(NH3)5Cl]Cl2 and [Rh(NH3)Br]Br2, is that neither Cl nor Br exert a static intramoleculartrans effect. Furthermore, the two halogens have the same static electronic structural effect on the [RhIII(NH3)5] fragment. The conclusions shed much light on spectroscopic, thermodynamic and kinetic data of other compounds.