STUDY ON STRUCTURE-ACTIVITY-RELATIONSHIPS OF ORGANIC-COMPOUNDS - 3 NEW TOPOLOGICAL INDEXES AND THEIR APPLICATIONS

In this paper, three new topological indices, A(x1), A(x2), and A(x3), have been developed for use in multivariate analysis in structure-property relationship (SPR) and structure-activity relationship (SAR) studies. Good results have been obtained by using them to predict the physical and chemical properties and biological activities of some organic compounds.

ELECTROCATALYSIS AND DETERMINATION OF HYDRAZINE COMPOUNDS IN LIQUID-CHROMATOGRAPHY AT A MIXED-VALENT COBALT OXIDE CYANOCOBALTATE FILM ELECTRODE

A glassy carbon electrode coated with an electrodeposited film of mixed-valent cobalt oxide/cyanocobaltate (Co-O/CN-Co) enabled hydrazine compounds to be catalytically oxidized at the greatly reduced overpotential and in a wide operational pH range (pH 2.0-7.0). Electrocatalytic activity at the Co-O/CN-Co modified electrode was evaluated with respect to solution pH, film thickness, supporting electrolyte ions, potential scan rate, operating potential, concentration dependence and other variables. The Co-O/CN-Co film electrode was completely compatible with a conventional reversed-phase liquid chromatographic (RP-LC) system. Practical RP-LC amperometric detection (RP-LCEC) of hydrazines was performed. A dynamic linear response range over three orders of magnitude and a detection limit at the pmol level were readily obtained. The Co-O/CN-CO film electrode exhibited excellent electrocatalytic stability in the flowing streams.

SYNTHESIS AND CHARACTERIZATION OF BINUCLEAR ORGANOLANTHANIDE COMPLEXES INVOLVING CYCLOPENTADIENYL AND N-PROPYLOXIDE LIGANDS - X-RAY CRYSTAL-STRUCTURE OF [(C5H5)2YB(MU-OCH2CH2CH3)]2

By the reaction of Cp3Ln (Cp = C5H5; Ln = Dy, Ho, Yb) with equimolar n-propyl alcohol in THF (tetrahydrofuran) at room temperature three new binuclear organolanthanide complexes, [CP2Ln(mu-OCH2CH2CH3)]2 (Ln = Dy, Ho, Yb), have been synthesized, as shown by X-ray single-crystal structure analysis for the complex [Cp2Yb(mu-OCH2CH2CH3)]2. All the complexes were characterized by elemental analysis, IR and MS spectra. The Yb2O2 unit is planar, and the ytterbium atom is coordinated by two Cp ring centroids and two oxygen atoms of two n-propyloxide ligands to form a distorted tetrahedral geometry. The average Yb-C (Cp) bond distance is 2.589(17) angstrom. The average Yb-O distance is 2.199(5) angstrom. The Yb-Yb separation [3.521(1) angstrom] indicates that no metal-metal interaction is present.

CORRELATION-ANALYSIS IN STRUCTURE AND CHROMATOGRAPHIC DATA OF ORGANOPHOSPHORUS COMPOUNDS BY GAI

This approach is undertaken to examine the correlation ability of the general a(N)-index (GAI) to predict chromatographic behavior. The test is performed on various types of organophosphorus compounds. The results demonstrate that the GAI possesses a good correlation with chromatographic properties.

SYNTHESIS, THERMAL-STABILITY AND X-RAY CRYSTAL-STRUCTURE OF THE BIS(CYCLOPENTADIENYL)YTTERBIUM NAPHTHOXIDE DERIVATIVE (C5H5)2YB(OC10H7)(THF)

Cp3Yb (Cp = C5H5) reacts with a-naphthol (HNP) in THF to form Cp2Yb(NP)(THF) (1), which crystallizes in the space group P2(1)/n with unit cell dimensions a = 8.084(2), b = 15.996(6), c = 15.973(7) angstrom, beta = 98.95(3), V = 2040.3 angstrom and D(calc.) = 1.69 g cm-3 for Z = 4. Least-squares refinement based on 2242 observed reflections converged to a final R value of 0.081. The average Yb-C(Cp) distance is 2.60(2) angstrom and Yb-O(THF) and Yb-O(NP) distances are 2.30(1) and 2.06(1) angstrom, respectively. The title compound loses the coordinated THF molecule readily by heating under vacuum to give dimeric [Cp2Yb(NP)]2 (2), which undergoes disproportionation to give Cp3Yb and Yb(NP)3 on heating above 230-degrees-C.

RAMAN-SPECTROSCOPIC STUDY OF THE PEROVSKITE LAYER STRUCTURE COMPOUNDS - [N-CNH2N+1NH3]2ZNCL4

The C-H stretching, C-H bending, C-C stretching and the low-frequency vibrational regions have been investigated by Raman spectroscopy for [n-CnH2n+1NH3]2ZnCl4 with n = 7-12, 16. The frequencies and relative intensities are related to the length of the carbon chain in the molecules and present the odd-even effect of the carbon atom numbers in the chains. Some changes in the spectra are interpreted in terms of the different molecular packing.

ELECTROCATALYTIC OXIDATION AND FLOW DETECTION OF HYDRAZINE COMPOUNDS IN LIQUID-CHROMATOGRAPHY AT A VITAMIN-B-12 ADSORBED GLASSY-CARBON ELECTRODE

A vitamin B-12 chemically modified electrode (CME) was constructed by adsorption of vitamin B-12 onto a glassy carbon surface. The electrode catalyzes the electrooxidation of hydrazine compounds over a wide pH range. The electrocatalytic behavior of hydrazines is elucidated with respect to the CME preparation conditions, solution pH, operating potential, mobile phase flow rate, and other variables. When applied to liquid chromatographic detection of the analytes, the vitamin B-12 CME yielded a linear response range over 2 orders of magnitude, and detection limits at the picomole level. The vitamin B-12 CME offers acceptable catalytic stability in both batch and flow systems.

SYNTHESIS AND CRYSTAL-STRUCTURE OF THE TRIS(CYCLOPENTADIENYL)PHENYL COMPLEX OF NEODYMIUM, (LI-BULLET-3DME)[(ETA-5-C5H5)3NDC6H5]

(Li.3DME)[eta(5)-C5H5)3NdC6H5], 1 was synthesized by the reaction of NdCl3.2LiCl, 2 equivalents of cyclopentadienylsodium and one equivalent of phenyllithium in THF at -78-degrees-C, and crystallized from THF and DME. The crystal structure of 1 was determined by X-ray diffraction method at -80-degrees-C. The crystal of 1 is triclinic, space group P1BAR with a = 15.752(6), b = 16.232(3), c = 23.038(7) angstrom, alpha = 108.81(2), beta = 93.31(3), gamma = 108.38(2)-degrees, Z = 6 and D = 1.33 g/cm3. Least-squares refinement (5732 observed reflections) led to a final R of 0.053. The complex consists of disconnected ion pairs of (Li.3DME)+ and [(eta(5)-C5H5)3NdC6H5]-. The neodymium atom was connected to three eta(5)-bonded cyclopentadienyls and one sigma-bonded phenyl in a distorted tetrahedral arrangement with Nd-C(sigma-) 2.593(17), 2.613(13) and 2.601(13) angstrom.

STUDY ON BONDING AND 4F ORBITAL EFFECT OF LANTHANIDE COMPOUNDS

The bonding and the 4f orbital effect of lanthanide elements at different valence state in their compounds have been studied by INDO method in this paper. The results obtained show that the bonding of lanthanide compounds is affected by many factors, such as valence state, ionic radius, ligand, coordinate number, space configuration etc. The strength of bonds composed of different ligands with lanthanide is distinctly different. The covalence of Ln-L bonds of lanthanide ions at high valence state in their compounds is larger than that at low valence state, The covalency at low coordinate number is larger than that at high coordinate number. Some lanthanide compounds with special configuration, besides sigma-bond, can form p(pi)-d(pi) dative bond with much overlap, which makes the Ln-L bond increase markedly. The effect of 4f orbitals on bonding is far less than that of 5d orbitals. The Ln 4f orbitals at 3 or 2 valence state may be considered to be essentially localized, while the contribution of 4f orbitals on bonding in 4 valent cerium compounds increases obviously, up to 1%.

THERMAL-OXIDATION OF POLYPROPYLENE CONTAINING HINDERED PIPERIDINE COMPOUNDS

The thermal oxidation behaviour of polypropylene containing tetramethylpiperidine compounds and corresponding pentamethylpiperidine compounds are compared using air oven aging, oxygen uptake and thermogravimetry. Carbonyl formation, the induction period of oxygen absorption and weight loss have been selected to characterize the degree of oxidation. The results show that the stabilizing effectiveness of pentamethylpiperidines is always higher than that of tetramethyl types. Radical-trapping mechanisms cannot explain this, because large amounts of nitroxyl radicals are formed by the tetramethylpiperidine compounds. The quenching of singlet oxygen appears to be involved in thermal oxidation of polypropylene containing pentamethylpiperidine compounds. Specific hydrogen bonding between pentamethylpiperidines and hydroperoxide may account for their better thermal stabilizing action than tetramethylpiperidines.

A MASS-SPECTROMETRIC STUDY OF ORGANIC PHOSPHORUS-COMPOUNDS .5. EI SPECTRA OF 1, 3, 2-OXAZAPHOSPHOLIDINE 2-SULFIDES DERIVATES

The mass spectral behaviour of 15 new type of organic phosphorus compounds with a considerable insecticidal activity, 1, 3,2-oxazaphospholidine 2-sulfides derivatives, under 70 eV electron impact has been studied by means of high and low resolution mass spectrometry as well as by B/E linked scan and MIKES/CID analysis. Discussion is focused into the isomerization between oxygen and sulphur in molecules and some rearrangement reactions.

GENERAL ALPHA-N INDEX AND ITS APPLICATION .2. THE CORRELATION BETWEEN THE GENERAL ALPHA-N INDEX AND PHYSICAL-PROPERTIES OF NEUTRAL PHOSPHORUS-COMPOUNDS

The relationship between the alpha-N index and physical properties of neutral phosphorus extractants is studied. Using the general alpha-N index which could describe extractants with minute difference in structure, the good correlation between it and various physical properties of the neutral phosphorus extractants (e.g., densities, refractive index, shift ratio of paper chromatography and IR frequencies of bond P = O) is obtained. The result indicates that general alpha-N index is a good topological index of organic compounds.

THE COMPOSITIONS AND STRUCTURES OF SOME COMPOUNDS IN THE SYSTEM CA-SR-CU-O

The system of Ca-Sr-Cu-O have been investigated. Two new compounds with compositions Sr3Cu5O8+alpha and CaSrCu3O5+alpha have been discovered. Both are orthorhombic with a = 6.489, b = 11.280, c = 12.240 angstrom for CaSrCu3O5+alpha and a = 3.950, b = 11.479, c = 13.420 angstrom for Sr3Cu5O8+alpha. The X-ray powder data for CaSrCu3O5+alpha, Sr3Cu5O8+alpha, Sr2CuO3 and SrCuO2 are presented. The oxidation state of Cu ion and oxygen contents are analyzed by iodometric titration. Sr0.5Ca0.5CuO2 that has a similar structure with SrCuO2 has been found and its X-ray data are presented also.

SYNTHESIS OF A NEW TYPE OF CH3CN-COORDINATED LANTHANIDE COMPOUNDS LN(CH3CN)9(ALCL4)3CH3CN

Acetonitrile is a weakly donating ligand. The cationic compounds of CH_3CN-coordinated transition metal are versatile homogeneous catalysts for the polymerization and isomerization of olefins and cycloolefins. The cationic compound of lanthanide[Eu(CH_3·CN)_3(BF_4)_3]_n was prepared from the oxidation of Eu with NOBF_4 in CH_3CN by Thomas in 1986. It was found that [Eu(CH_3CN)_3(BF_4)_3]_n can catalyze the polymerization of styrene cyclohexadiene and other olefins. However, there is no information about...