J. R. Lechat

Reactivity of cyclopalladated compounds: VIII. Synthesis of cyclometallated compounds with an oxygen as the donor atom. Crystal and molecular structure of (8-methylquinoline-C,N)-(1-methoxynaphthalene-8-C,O)palladium(II)☆

Treatment of 1-methoxynaphthalene (MXNH) with n-butyllithium in a diethyl ether/n-hexane solution gives 1-methoxynaphthalene-8-lithium (MXNLi) in 30% yield as an insoluble material. This compound reacts with PdCl2(SEt2)2 to give bis(1-methoxynaphthalene-8-C,O)palladium(II) (I)_and with PtCl2(SEt2)2 to give cis- and trans-(1-methoxynaphthalene-8-C,O)(1-methoxynaphthalene-8-C)(diethylsulfide)platinum(II) (II), which are non-rigid molecules in solution. With the cyclopalladated dimers [{Pd(CN)Cl2}2], MXNLi gives the palladobicyclic compounds: (N∩C)Pd(C∩O) (III). An X-ray diffraction study of compound IIIa where N∩N = 8-methylquinoline-C,N reveals the planarity of the molecule, shows that it has a cis configuration with respect to the PdC bonds, and confirms that the oxygen atom of MXN is bonded to palladium: PdO 2.236(4) A. The geometry of IIIa is maintained in solution, whereas the corresponding compounds IIIb and IIIc in which N∩C is benzo[h]quinoline-9-C,N and N,N-dimethyl-1-naphthylamine-8-C,N, respectively, appear to be mixtures of cis and trans isomers in solution. With PMe2Ph I and II give trans-Pd(MXN)2(PMe2Ph)2 and cis-Pt(MNX)2(PMe2Ph)2, respectively, in which the methoxynaphthalene is bound to the metals via the 8-carbon of the naphthalene ring. Only one phosphine ligand adds to compounds IIIb and IIIc with displacement of the O → Pd bond. One carbon monoxide ligand can be added to the platinum compound II to give Pt(MXN)2(SEt2)CO which in solution exists as two isomers in equilibrium.

Adducts of cadmium diethyldithiocarbamate with bidentate nitrogen ligands

Abstract Reactions of Cd(S2CNEt2)2 with 1,10-phenanthroline or 2,2′-bipyridine produce crystalline 1:1 adducts. Thermogravimetric studies show that the 2,2′-bipyridine adduct initiates decomposition by loss of the neutral ligand whereas the 1,10-phenanthroline adduct undergoes a more complex decomposition. The crystal structure of the adducts show their monomeric nature with hexacoordination of the metal in a distorted octahedral geometry.

Lanost-7-en triterpenes from stem bark of Santiria trimera

Abstract The stem bark of Santiria trimera has yielded four triterpenes, friedelin, lupeol, and two lanost-7-en derivatives that appear to be novel. The two new compounds were identified on the basis of spectroscopic analysis as 20( R ),24( E )-3-oxo-9β-lanosta-7,24-dien-26-oic acid and 20( R ),24( E )-6β-acetoxy-3-oxo-9β-lanosta-7,24-dien-26-oic acid, the structure of the former being confirmed by X-ray diffraction analysis.

Electronic spectra, ESR and crystal structure of tetrahedral halocuprates(II). The existence of cations (2tbpo·H+) with a very short hydrogen bond

Abstract Two compounds [2tbpo·H + ) 2 [CuCl 4 ] = (yellow) and (2tbpo·H + ) 2 [CuBr 4 ] = (dark purple) (tbpo = tribenzylphosphine oxide) have been prepared and investigated by means of crystal structure, electronic, vibrational and ESR spectra. The crystal structure of the (2tbpo·H + ) 2 [CuCl 4 ] = complex was determined by three-dimensional X-ray diffraction. The compound crystallizes in the space group P 4 2 / n with unit-cell dimensions a = 19.585(2), c = 9.883(1)A, V = 3790 (1)A 3 , Z = 2, D m = 1.303 (flotation) D x = 1.302 Mg m −3 . The structure was solved by direct methods and refined by blocked full-matrix least-squares to R = 0.053 for 2583 observed reflections. Cu(II) is coordinated to four chlorides in a tetrahedral arrangement. Tribenzylphosphine oxide molecules, related by a centre of inversion, are connected by a short hydrogen bridge. Chemical analysis, electronic and vibrational spectra showed that the bromide compound is similar to the chloride one and can be formulated as (2tbpo·H + ) 2 [CuBr 4 ] = . The position of the dd transition bands, the charge transfer bands, the ESR and the vibrational spectra of both complexes are discussed. The results are compared with analogous complexes cited in the literature.

REACTIONS OF MERCURIC ACETATE WITH PENTACARBONYLIRON IN ALCOHOLS - CRYSTAL AND MOLECULAR-STRUCTURES OF HG[FE(COOR)(CO)(4)](2) (R=CH3, C2H5)

Reactions of Hg(CH3COO)2 with [Fe(CO)5] in MeOH and EtOH lead to the compounds Hg[Fe(COOR)(CO)4]2 (I for R = CH3 and II for R = C2H5). Crystals of I are triclinic, P1, with a = 6.272(2), b = 6.441(3), c = 11.703(4) A, α = 92.94(3)°, β = 103.77(3)°, γ = 96.10(2)°, and Z = 1. Crystals of II are tetragonal, I41/a, with a = 17.906 (3) A, c = 12.756(2) A, and Z = 8. The geometry around Hg is linear for compound I and approximately linear for compound II. The HgFe distances are 2.5716(8) and 2.575(4) A for compounds I and II, respectively. The geometry around the Fe in both compounds is approximately octahedral. The carboalkoxy group is cis to Hg in both compounds with FeC distances equal to 2.034(6) and 2.05(4) A for compounds I and II, respectively.

Crystal structure of the 1:1 complex formed by 4-nitropyridine N-oxide and 4-nitrophenol

The title complex (C6H5NO3·C5H4N2O3,Mr=279.21) crystallizes in the orthorhombic space groupPna21 witha=18.862(2),b=5.876(1),c=10.803(2) Å,V=1197.3(6) Å3,Dc=1.549 g cm−3 forZ=4,F(000)=576, λ(MoKα)=0.71073 Å,μ=0.84 mm−1,T=297 K. The structure was solved by direct methods and refined by block matrix least-squares. FinalR=0.032, wR=0.037 for 904 observed reflections. The complex is held together by an intermediate hydrogen bond between the hydroxyl and the N-oxide group with an O⋯O distance equal to 2.618(3) Å. The stacking of thea glide related complex molecules by translation in theb direction results in a herringbone structure with an overlap of the nitrophenol and 4-nitropyridine N-oxide rings and a mean interplanar distance of 3.4(1) Å between those rings.

Two pyrano flavones from Neoraputia alba

Abstract The petrol extract from leaves of Neoraputia alba yielded two flavones, in addition to sitosterol. The two new flavones were identified as: 7,8,3′,4′-tetramethoxy-6,5-(2″,2″-dimethylpyran)flavone and 7,8,3′,4′,5′-pentamethoxy-6,5-(2″,2″-dimethylpyran)flavone. The compounds were identified by spectroscopic analysis. The structure of the first compound was confirmed by X-ray diffraction.

Study of Ca2Fe2−xNbxO5+x phases by X-ray diffraction, IR and EPR spectroscopy

Abstract Samples of Ca 2 Fe 2 − x Nb x O 5 + x with o ≦ x ≦ 1.00, were synthesized at different temperatures between 1000°C and 1300°C and studied by X-ray powder diffraction, IR and EPR spectroscopy. A pure orthorhombic phase was obtained for low Nb concentrations (0 ≦ x ≦ 0.20, thermally treated at 1000 – 1100°C), as shown by X-ray diffraction, while a cubic phase was obtained for 0.45 ≦ x ≦ 1.00, at T = 1300°C. A mixture of phases was observed in the other cases. The presence of the different phases was verified by IR and EPR measurements correlated with X-ray diffraction results. The Nb concentration strongly affected the structure, optical and magnetic properties of the ferrite.

The 1:1 Complex Formed by 4-Nitropyridine N-Oxide and 4-Aminobenzoic Acid

The co-crystal, C 5 H 4 N 2 O 3 .C 7 H 7 NO 2 , owes its formation to an intermolecular hydrogen bond between the N-O and O-H groups. The crystal structure exhibits overlap between the rings of the molecules in the [110] direction. There is no short nitroamino intermolecular distance.

Structure of (4α)-13-hydroxykaur-16-en-18-oic acid (steviol) methanol solvate

C20HDoOD.CH40 , Mr = 350.50, ortho- rhombic, P212~21, a = 7.407 (2), b = 14.442 (3), c = 17.696 (3)/~, V= 1893 (1) ,A, 3, Z = 4, Din(flota- tion) = 1.20 g cm- 3, Dx = 1.230 g cm- 3, A(Cu Ka) = 1.54056 ,~, ~ = 6.3 cm- ~, F(000) = 768, T = 298 (1)K, final R--0.058 for 1675 observed reflec- tions. The hydrogen-bonding scheme consists of head-to-tail associated steviol molecules forming a ribbon in the a direction. The methanol molecule is hydrogen bonded to the carbonyl of the carboxyl group (acceptor) and to the hydroxyl group (donor) of associated steviol molecules. Introduction. As a result of the banning of cyclamate for use as a non-nutritive sweetener and of the question raised regarding the possible carcinogenicity of saccharin, a great deal of work has been carried out recently directed toward the development of alternative sweeteners. Stevioside (I), the extremely sweet diterpenoid glycoside found in the South American shrub Stevia rebaudiana, has been valued as a sweetener by the indigenous population. More recently, the plant source has been cultivated quite intensively in Japan where the product is approved for use in food. Enzymatic hydrolysis of the diterpenoid glycoside stevioside by the gastric juices of the snail, Helix pomatia (Bridel & Lavieille, 1931), pectinase (Ruddat, Heftmann & Lang, 1965) or hesperidinase (Mizukami, Shiba & Ohashi, 1982), affords the agly- cone steviol (II). Studies of the sweeteners of ste- vioside analogue compounds suggest that all of the functionality involved in receptor binding is located