VALENCE STATE OF C AtOMS AND σ_t-η_n SEPARABILITY OF MOLECULAR ORBITALS IN THE (BUCKMINSTER)FULLERENE C_(50)

The valence state of C atoms and the structure of molecular orbitals of the (Buckminster)Fullerene C_(60)have been demonstrated. It has been shown that when a motion-coordinate system is adopted, in which the coordinate origin is at every C atom, the z axis is in the direction of the normal and the (x,y) axes are in the direction of tangents of C_(60)'s spherical surface, 240 valence atomic orbitals of C_(60) can be divided into two groups. All (P_x, P_y)atomic orbitals named as Pt ones and all the other P_z atomic orbitals named as p. ones, That is to say that if we name the molecular orbital linearly combined of P_t atomic orbitals as σ_t and the molecular orbital linearly combined of P_n atomic orbitals as π_n, the 240 valence molecular orbitals are of the property of σ_t-π_n separability. It has also been shown that the frontier and nearby frontier molecular orbitals are π_n ones, and therefore the essential physical and chemical properties of C_(60) are determined by its π_n molecular orbitals.     

ELECTROREDUCTION MECHANISM OF Ni(DMG)-2 COMPLEX STUDIED WITH QUANTUM CHEMICAL METHOD

The electronic structures of the species Ni(DMG)_2, (Ni(DMG)_2)~- and (Ni(DMG)_2)_(2-) have been studied by INDO quantum chemical method. The results have clearly shown that in the first stage of the electroreduction of Ni(DMG)_2, one electron interacts with the d orbitals on the nickel atom, while in the further stage the second electron interacts with the p orbitals on the nitrogen atoms. It conforms with our electrochemical experimental studies which showed that not only Ni(Ⅱ) is reduced but also DMG is catalytically reduced during the reduction of Ni(DMG)_2.     

RULE OF DISTRIBUTION OF PHASE POINTS OF POLY-UNIT MOLECULES AND HOMOLOGOUS LINEAR LAW

The chain M-(A)_n-N or ring obtained by bonding n number of A's with the same chemical structure in the same way is called the poly-unit molecule. Jiang Mingqian has discovered the famous homologous linear law for the poly-unit chain. Xu Guangxian and Li Lemin have studied its quantum-chemical basis and put forward the new linear factor.In order to study further the basic quantum chemistry of the homologous linear law, it is necessary to have first a thorough knowledge of the orbital characteristics of the polyunit molecules. The author studied the orbitals and the energy levels of poly-unit molecules by using difference equations. Based on the past work the concept of phase points of orbital was established, and the rule of distribution of phase points was developed as well. It is found that the phase points of similar orbitals in the molecules of a homologous series appear to condense around a certain point. Based on this fact a theoretical proof of the homologous linear law was made.     

THE NATURE OF MOLTEN-SALT-LIQUID-METAL SOLUTIONS

The microscopic structure of certain molten-salt-liquid-metal solutions has been investigated by quantum chemical method. It is indicated that (ⅰ) Li_(n 1)~(n ) or Li_(n 2)~(n ) ions form in Li-LiF melt. The valence electrons of Li atoms delocalize into all vacant orbitals of neighboring cations; (ⅱ) lithium fluoride, dissolving in liquid lithium, forms F~- ions in liquid metal, and the vacant orbitals of Li~ ions of the salt take part in the delocalization with the electrons of metallic bond. It is this delocalizatin energy that makes this solution thermodynamically stable; (ⅲ) Mg_2~(2 ) is unstable as compared with Mg~ or Mg_2~ . The experimental results of mass-spectroscopy also indicate the existence of Mg~ abd Mg_2~ , but not Mg_2~(2 ). The state of Mg dissolving in molten salt is discussed based on the results mentioned above.     

ELECTRONIC ENERGY BAND STRUCTURE OF MOLECULAR CRYSTAL TTF-TCNQ——CHANGE OF ENERGY BAND STRUCTURE DURING PEIERLS PHASE TRANSITION

In this paper, the electronic energy bands of the molecular crystal TTF-TCNQ have been calculated. The results demonstrate that the positions and the widths of the energy bands of this crystal conform to the rules given by our previous paper exactly, i.e. the positions of the energy bands of crystal orbitals are determined by the energy levels of corresponding molecular orbitals of the isolated molecules, and the widths of the energy bands are determined by the interaction between the molecular orbitals belonging to different molecules in the crystal. The results also demonstrate that the dimerization which appears after Peierls phase transition has a considerable effect on band widths. The dimerization causes the band widths of TTF and TCNQ columns to become narrow sharply. According to the relationship between the mobility of charge carriers and the band width given by Frhlich and Sewell, the sharp change of electrical conductivity of TTF.TCNQ crystal during Peierls phase transition can be explained p     

THE STABILITY OF LAIHUNITE——A THERMODYNAMIC RE-ANALYSIS

A topological analysis on the ternary 7-phase multisystem involving laihunite (FeO-Fe_2O_3-SiO_2; Q-H-M-W-L-Fa-fs) in P-T plane has resulted in an n+4 phase closed-net-diagram. The most possible straightline-net-diagram was derived by using the thermodynamic properties of the phases concerned. From the straight-line-net-diagram it is apparent that laihunite is not a phase stable only at high pressures. P-T-fo_2, analysis suggests that the formation and stabilization of laihunite are closely related to oxygen fugacity. However, laihunite shows different ways of formation at different pressures. At low pressures, it is formed via the oxidation of fayalite; with increasing pressures the contribution of ferrosilite to the formation of laihunite increases; at very high pressures laihunite can be formed only by the oxidation of ferrosilite.     

STUDY ON ELECTRONIC STRUCTURE AND BONDING OF CLUSTER COMPOUND Sc_7Cl_(10)C_2

<正> The electronic structure and bonding of the cluster compound Sc7Cl10C2 have been studied by INDO method. In contract to the weak interaction between metal-metal in the compound Gd10Cl18C4, the bonding between metal atoms (Sc-Sc) in Sc7Cl10C2 is rather strong. The contribution of the orbitals 4s and 4p is larger than that of 3d to the Sc-Sc bond. In the cluster compound, besides Sc-Sc bonding, there are Sc -C and Sc -Cl bonds. The contribution of 3d is larger than that of 4s and 4p to the bond Sc-C. The contribution of 3d is slightly less than that of 4p and 4s to the bond Sc-Cl. Among the three kinds of bonds, the Sc-Cl bond is the weakest, the bond order of the Sc-Sc is close to that of the Sc-C.     

REGIONAL ASSIGNMENT OF HUMAN ALCOHOL DEHYDROGENASE (ADH) GENE TO 4pter→4q21

The hybrid clone FD1 constructed by fusion of Chinese hamster cell line Wg3-h with human lymphocyte was irradiated with X-ray. Fourteen survival clones were isolated and 3 of them, F5B, F52B, F61A were analyzed in detail by cytogenetic and biochemical methods. The results of chromosome Gbanding followed by Giemsa-11 differential staining show that there exists a deleted human chromosome 4 in all of the three hybrids. This deletion of human chromosome 4 in F61A is 4pter→4q21. The results of isozyme analysis of phosphoglucomutase-2 (PGM2) which is located on 4p14→4q21 confirm our cytogenetic conclusion. We used polyaerylamide gel electrophoresis to study the alcohol dehydrogenase (ADH) in human lymphocyte, Wg3-h and hybrid clones. Their electrophoretic pattern showed that human ADH isozyme did express, in the peripheral blood lymphocyte, hybrids FSB, F52B, F61A and FD1. According to these results, we suggest that one of the Class 1 ADH structural genes is located on the human chromosome 4pter→4q21. Rec     

STUDY OF XPS AND EHMO CALCULATION ON SILATRANE COMPOUNDS

Twenty silatrane compounds with different substituents(R) on the silicon atom are studied by means of X-ray photoelectron spectroscopy(XPS) and EHMO(extended Hückel molecular orbitals) theoretical calculation of the nine compounds in which substituents(R), F, Cl, Br, I, CH_3, H, CH=CH_2, CH_2Cl and CHCl_2, are carried out. By the X-ray photoelectron spectra of the component elements in these compounds, the existence of N→Si dative bond in these molecules is not only confirmed, but the affection of the different substituents on the strength of N→Si dative bond is also obtained. A linear correlation exists between atomic netcharge(Q) obtained by EHMO calculation and the binding energy shifts of N_1_g and Si_(2p) due to different substituents. The calculated bond orders can well predict the effect ou the strength of N→Si dative bond due to the change of substituents in the experiment. Meanwhile, the calculations indicate that the strength of N→Si dative bond in molecules of all substituents is about h     

COORDINATION POLYMERIZATION OF BENZOTRIAZOLE ON THE SURFACE OF METALLIC COPPER

The coordination polymerization of benzotriazole with metallic copper has been investigated by infrared and X-ray photoelectron spectroscopies. We found that benzotriazole could react with copper (0) under mild conditions to form bis (benzotriazolato) copper (Ⅱ) and benzotriazolato copper (Ⅰ)which covered the surface of copper metal in the shape of polymeric materials. Since benzotriazole is of great interest as a ligand in that its presence in many biological system with metal ions, and is considered as a corrosion inhibitor, this work will be in favour of the study of protective corrosion.     

X-RAY STUDIES ON THE STRUCTURE OF DES-PENTAPEPTIDE INSULIN AT 2.4 RESOLUTION——THE DPI MOLECULE AND ITS STRUCTURAL RELATIONSHIP WITH INSULIN

The structure of the monomeric insulin analogue des(B26—B30) insulin is presented.; A detailed comparison with the 2Zn insulin structures shows that while there are some large changes in the structure, the basic secondary structural units maintain their integrity. The DPI structure is broadly similar to molecule Ⅰ in the 2Zn structure, and in this respect is like other crystal forms of insulin. In addition to changes on the surface of the structure there are some subtle but extensive changes in the heart of the molecule. The molecules are closely packed in the crystal with many and varied contacts, including a complex network of protein-cadmium interactions and a considerable number of water mediated contacts. The molecular surface has an unusually large number of hydrophobic groups which tend to cluster in a thick band running around the protein. The crystal structure is well ordered, indeed the clarity of some side chains and the definition of the water molecules is superior to that found in the mor     

SEPARATION OF IRON AND MANGANESE IN THE EARLY DIAGENETIC PROCESSES AND ITS MECHANISM OF BIOGEOCHEMISTRY

Study shows that the reduction of iron (Fe~(3+)) and manganese (Mn~(4+)) in modern sedi-ments and the diffusive flux of the Mn~(2+) from the pore water into the overlying waterare mainly controlled by bacteria, and the distribution of the bacteria is believed to beaffected strongly by the sedimentary environment. It is the diffusive fluxes between Fe~(2+)and Mn~(2+) that lead to the separation of iron and manganese in the modern sediment at theChangjiang Mouth and near the shore. The level of the separation decreases with theincrease of the overlying water salinity and increases from the surface to the depth. Thismechanism has given a new explanation why manganese is concentrated in sediments onthe oceanic floor of ferromanganese-rich nodules.     

THE CTYSTAL STRUCTURE OF m—FERROCENYLACETOOHENONE

<正> The title compound C18H16FeO (Mr=304. 17) crystallizes in the mono-clinic system,space group P21/c with cell constants a= 14. 428(3),b=9. 939(8),c = 10. 027(5) A .B=93. 73(1),Z=4,Dc=1.41 gcm-3 and V= 1435. 0A 3.The structure is solved by direct methods and refined by least-squares technique to final R=0. 038 and Rw=0.051 based on 2413 independent reflections with I>3o(I). Result shows that both the Cp rings are approximately parallel with dihedral angle of 1. 2 ,The phenyl ring is somewhat tilted from the Cp ring linked to it with a dihedral angle of 8. 36 . The oxygen and carbon atoms of the aceto group are almost co-planar with the phenyl ring.     

TRANSAMIDATION IN THE in situ BLENDING OF POLYAMIDE 1212 WITH POLYAMIDE 6 THROUGH ANIONIC POLYMERIZATION OF CAPROLACTAM

20 wt% polyamide 12(PA1212)pellets were dissolved in molten caprolactam.The caprolactam was then catalyzed at 180℃and polymerized by means of anionic ring-opening polymerization to produce in situ blends of the resultant polyamide 6(PA6)and PA1212.Mechanical blends with same ingredient were prepared through melt blending on a twin-screw extruder.Scanning electron microscopy(SEM)observation revealed that contrary to the mechanical blends with small spherulites embedded in the matrix,no phase-separation existed in the in situ blends.The results of thermal analysis by differential scanning calorimetry(DSC)showed that single melting peak and crystallization peak existed for the in situ blends,while two melting and crystallization peaks appeared for the mechanical blends.The in situ blend film and the mixed blend film,both cast from a dilute formic acid solution with a concentration of 0.5 g/L,remained similar crystallization and melting behavior as above.It is proved by solution ~(13)C-NMR analysis that transamidation took place during the in situ blending,and it is suggested that the combination of temperature increasing and the basic surrounding derived from NaOH during polymerization resulted in the occurrence of transamidation.Furthermore,it is proposed that the interchange reaction between PA1212 and PA6 also resulted from the degradative reaction during the anionic polymerization.     

Theoretical Study on the Reaction of Thymine with Iodomehane in the Water Phase

The reaction mechanisms of carcinogenic methylating agent iodomethane (MeI) with keto and enol tautomers of thymine (K- and E-thymine) were studied by using the B3LYP/6-311+G (d, p) method in water phase. The solvent effects were examined using the polarizable continuum model (PCM). Specifically, PCM single-point calculations at the same level of theory were performed in acetone and CCl4 that represent a range in nonpolarity. The calculated results show that the reaction of K-thymine with MeI is a two-step mechanism, whereas that of E-thymine is a one-step mechanism. Our calculations reveal that K-thymine is appreciably more stable than the enol form in the water phase or in the two solvents. The K- and E-form reaction barriers are 135.6 and 222.1 kJ/mol, respectively in water phase. These findings indicate that the reactions mentioned above could not occur efficiently in biological media in the absence of catalyst. Our conclusions are in agreement with the previous studies on the reactions of guanine with methyl chloride and methyl bromide.     

ESR SPECTRA STUDY OF COPPER(Ⅱ) COORDINATION COMPLEXES OF PYRIDI

The ESR spectra of powdered samples of Cu(Ⅱ) complexes with pyridine and its sixhomologues and pyrrol, aniline, as well as their solutions are measured at 77K in this paper.The electronic levels of these complexes are calculated from the ESR spectral parameters.It is found that the non-pyridine ligands of complexes which can be substituted by pyridinemolecules of solvent in solution of pyridine/chloroform form Py_4Cu~(2 ). A molecular configura-tion is proposed. for Py_4Cu~(2 ) in solution. It is shown that the treatment with D_(2h) symmetryinstead of D_(4h) symmetry leads to a more satisfactory explanation of the ESR spectra.     

MOLECULAR VOLUMES OF SALTS. WITH TRIANGULAR RADICALS

The present paper discusses some characteristics of the molecular volumes of carbonates, nitrates and borates. It confirms that the molecular volume of H_2O in the hydrates of this kind of salts approximates to a constant. When the coordination numbers of cations in mixed salts are identical with those in the single salts, the additivity of the molecular volume is quite accurate. Over 100 sets of data demonstrate that a general additivity is true, the average relative error being ±2.31%. The concept of the topological molecular volume is proposed based, on the additivity. For salts with the same radical and equally charged cations, the molecular volume varies linearly with the cation radius. The volume effects of CO_3~(2-) NO_3~- and BO_3~(3-) in packing can be obtained by extrapolation. They are equal to a large sphere whose volume is the sum of those of three O~(2-). This paper also discusses the possibility of compiling a table of ionic volumes.     

THE CRYSTAL STRUCTURE OF BAYLEYITE

The bayleyite crystallizes in monoclinic space group C_2~5h-P2_1/c with a=6.499(1), b=15.235(5), c=26.513(6), β= 92.92(2)°, Z=4. Intensities of 3430 independent reflections are collected with diffractometer using MoKα radiation. The crystal structure has been solved by the Patterson method and refined by block least square refinement for positional parameters and isotropic temperature factor of non-hydrogen atoms. The final R factor is 0.038.The result of crystal structure analysis shows that the structure consists of discrete [UO_2(CO_3)_3]~(4-) ions and Mg~(2 ) cations are between slab-like units, but they are not in a slablike unit. Its crystal struture is different from that of liebigite which was determined by Appleman. Complexes and cations between slab-like units and in a slab-like unit are connected by hydrogen bonds formed by water molecules.     

CHARACTERIZATION OF RADIATION GRAFTING DEGREE OF POLYSTYRENEg-ACRYLIC ACID BY XPS

In this work, characterization of radiation grafting degree of polystyrene-g-acrylic acid by XPS was studied. It is found that along with the main peak C_(1s) there is a photoelectron peak at 289.0 eV that appears to be C_(1s) of-(?)-OH group and shows the presence ofpolyacrylic acid grafted on the polystyrene The grafting degree obtained by XPS is in agreement with that from the gravimetric method.     

Water effect on peroxy radical measurement by chemical amplification: Experimental determination and chemical mechanism

The water effect on peroxy radical measurement by chemical amplification was determined experimentally for HO2 and HO2 OH, respectively at room temperature (298±2) K and atmospheric pressure (1×105 Pa). No significant difference in water effect was observed with the type of radicals. A theoretical study of the reaction of HO2·H2O adduct with NO was performed using density functional theory at CCSD(T)/6-311 G(2d, 2p)//B3LYP/6-311 G(2d, 2p) level of theory. It was found that the primary reaction channel for the reaction is HO2·H2O NO→HNO3 H2O (R4a). On the basis of the theoretical study, the rate constant for (R4a) was calculated using Polyrate Version 8.02 program. The fitted Arrenhnius equation for (R4a) is k = 5.49×107 T 1.03exp(?14798/T) between 200 and 2000 K. A chemical model incorporated with (R4a) was used to simulate the water effect. The water effect curve obtained by the model is in accordance with that of the experiment, suggesting that the water effect is probably caused mainly by (R4a).