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51.
Summary [NiL2X2] (L =N,N-dimethyl-1,2-ethanediamine; X = Cl–, CF3CO
2
–
, CC13CO
2
–
and CBr3CO
2
–
), [NiL2C2O4] · H2O and [NiL2X2] · 2 H2O (X = Br–, 0.5 SO
4
2–
and 0.5 SeO
4
–
) have been synthesised and their thermal studies carried out. Thermally induced phase transition phenomena are noticed in [NiL2X2] (X = CF3CO
2
–
and CCl3CO
2
–
) and their probable mechanisms are described. [NiL2X2] (X = Br–, 0.5 SO
4
2–
and 0.5 SeO
4
2–
) and [NiLX2] (X = Cl–, 0.5 C2O
4
2–
and 0.5 SO
4
2–
) have been prepared by solid state pyrolysis from the respective parent diamine complexes. [NiL2X2] have been made in solid state by temperature arrest technique from [NiL2(CX3CO2)2] (X = Cl– and Br–). 相似文献
52.
Noorjahan Begum Amarash C. Ghosh Shariff E. Kabir Md. Arzu Miah G.M. Golzar Hossain 《Polyhedron》2005,24(18):3074-3081
Four triosmium carbonyl clusters bearing terminal pyrazines, bridging hydroxy and methoxycarbonyl ligands of general formula [Os3(CO)9(μ-OH)(μ-OMeCO)L] (1, L = pyrazine; 2, L = 2-methylpyrazine; 3, L = 2,3-dimethylpyrazine; 4, L = 2,3,5-trimethylpyrazine) were synthesized by the reactions of [Os3(CO)12] with the corresponding pyrazine derivatives and water in the presence of a methanolic solution of Me3NO in moderate yields. Compounds [Os3(CO)9(μ-OH)(μ-OMeCO)L] react with a series of two electron donor ligands, L′ at ambient temperature to give [Os3(CO)9(μ-OH)(μ-OMeCO)L′] (5, L′ = PPh3; 6, L′ = P(OMe)3; 7, L′ = tBuNC; 8, L′ = C5H5N) in good yields by the displacement of the pyrazine ligands. This implies that the pyrazine ligands in 1–4 are relatively labile. Compounds 2, 3, 4, and 8 were characterized by single crystal X-ray diffraction analyses. All the four compounds possess two metal–metal bonds and a non-bonded separation of two osmium atoms defined by Os(1)Os(3), which are simultaneously bridged by OH and MeOCO ligands and a heterocyclic ligand is terminally coordinated to one of the two non-bonded osmium atoms. 相似文献
53.
Samanta S Ghosh D Mukhopadhyay S Endo A Weakley TJ Chaudhury M 《Inorganic chemistry》2003,42(5):1508-1517
The tridentate dithiocarbazate-based Schiff base ligands H(2)L (S-methyl-3-((5-R-2-hydroxyphenyl)methyl)dithiocarbazate, R = NO(2), L = L(2); R = Br, L = L(3)) react with [VO(acac)(2)] in the presence of imidazole derivatives as coligands to form oxovanadium(IV) and cis-dioxovanadium(V) complexes. With benzimidazole and N-methylimidazole, the products are oxovanadium(IV) complexes, viz. [VOL(3)(BzIm)].0.5CH(3)CN (1a) and [VOL(N-MeIm)(2)] (L = L(3), 1b; L = L(2), 1c), respectively. In both 1a,b, the O and S donor atoms of the tridentate ligand are cis to the terminal oxo group (in the "equatorial" plane) and mutually trans, but the N donor atom is respectively cis and trans to the oxo atom, as revealed from X-ray crystallography. When imidazole or 4-methylimidazole is used as the ancillary ligand, the products obtained are water-soluble cis-dioxovanadium(V) complexes [VO(2)L(R'-ImH)] (L = L(3) and L(2), R' = H and Me, 2a-d). These compounds have zigzag chain structures in the solid state as confirmed by X-ray crystallographic investigations of 2a,d, involving an alternating array of LVO(2)(-) species and the imidazolium counterions held together by Coulombic interactions and strong hydrogen bonding. Complexes 2a-d are stable in water or methanol. In aprotic solvents, viz. CH(3)CN, DMF, or DMSO, however, they undergo photochemical transformation when exposed to visible light. The putative product is a mixed-oxidation divanadium(IV/V) species obtained by photoinduced reduction as established by EPR, electronic spectroscopy, and dynamic (1)H NMR experiments. 相似文献
54.
Kallol K. Ghosh Pokhraj Sharma Samiksha Taramkar Santosh Kumar Sar 《Reaction Kinetics and Catalysis Letters》2004,81(1):161-168
The acid catalyzed hydrolysis of two N-substituted hydroxamic acids (C6H5CON(OH)R, R = C6H5 (PBHA), R = C6H5CH2(BBHA)) in mixed systems containing -cyclodextrin (—CD) and a surfactant (sodium dodecyl sulfate, SDS) has been studied. The reactions are inhibited by —CD. The inhibition is attributed to the formation of inclusion complex and competition between the micellization and complexation processes.This revised version was published online in December 2005 with corrections to the Cover Date. 相似文献
55.
Various alcohols and phenols can be smoothly converted to the corresponding THP ethers using 20 mol % CuSO4·5H2O under mild reaction conditions at room temperature. Some of the major advantages of this procedure are nonaqueous work-up, very good yields, less expensive catalyst and compatibility with other protecting groups. 相似文献
56.
The kinetics of the interaction of DL-methionine with [Pt(en)(H2O)2]2+ have been studied spectrophotometrically as a function of [Pt(en)(H2O)22+], [DL-methionine], PH and temperature. The reaction proceeds via a rapid outer sphere association followed by two slow consecutive steps having first order dependence on the aqua ion and methionine concentrations. Activation parameters have been evaluated using the Eyring equation. The low H1 (15.6 kJ mol–1) and large negative value of S1 (–230 J K–1 mol–1) as well as H2 (19.5 kJ mol–1) and S2 (–226 J K–1 mol–1) indicate an associative mode of activation for both the aqua ligand substitution processes in the two consecutive steps. 相似文献
57.
Summary From the conduotometrio and electrometric studies of the metathesis between beryllium chloride and sodium silicate, it has
been concluded that two silicates of beryllium are formed along with the formation of beryllium hydroxide and silicic acid.
It has been further concluded that the hydrolysis of beryllium chloride is not so great as that of chlorides of iron and chromium.
Zusammenfassung Aus Leitf?higkeitsmessungen und elektrometrischen Untersuchungen an Reaktionsprodukten aus Berylliumchlorid und Natriumsilikat wird auf Entstehung von zwei Berylliumsilikaten geschlossen, gleichzeitig auf Bildung von Berylliumhydroxyd und Kiesels?ure. Die Hydrolyse von Berylliumchlorid ist nicht so stark wie die von Eisen- und Chromchlorid.相似文献
58.
A density-functional theory is presented to study the structure of polymers, having attractive interactions, confined between attractive surfaces. The theory treats the ideal-gas free-energy functional exactly and uses weighted density approximation for the hard-chain contribution to the excess free-energy functional. The bulk interactions of freely jointed hard spheres are obtained from generalized Flory equation of state and the attractive interactions are calculated using the direct correlation function obtained from the polymer reference interaction site model theory along with the mean spherical approximation closure. The theoretical predictions are found to be in quite good agreement with the Monte Carlo simulation results for varying densities, chain lengths, and different interaction potentials. The results confirm important implications of using different approximations for the hard-sphere and attractive interactions. 相似文献
59.
Tarun Ghosh 《Tetrahedron letters》2004,45(32):6169-6172
C-(4-Oxo-4H-1-benzopyran-3-yl)-N-alkyl-/aryl-nitrones derived from 4-oxo-4H-1-benzopyran-3-carboxaldehyde, rearrange to 2-alkyl-/aryl-amino-3-formylchromone and/or 3-(alkyl-/aryl-aminomethylene)chroman-2,4-dione depending upon the reaction medium. 3-(Alkylaminomethylene)chroman-2,4-dione has been utilized in the synthesis of 1-benzopyrano[3,4-d]isoxazole-4-one. 相似文献
60.
Analytical properties of hydrogen-like atomic orbitals (HAO ) that are used in the MOLCAO approach to the quantum theory of molecules have been studied. Addition and expansion theorems for HAO have been proved, both in coordinate and momentum representations. A close relation has been established between HAO and the reduced Bessel functions of half-integer indices. New methods are suggested to calculate integrals for atomic and molecular form factors, and multicenter integrals, for the HAO basis in the MO LCAO theory. 相似文献